Reed switches do have some advantages compared to hall effect and optical switches, but they also have some faults. They have a shorter life span, lengthy switch bounce, and poor repeat-ability when used for positioning.
I was a bit surprised tomboardman passed on the optical sensors in favor of hall effect switches though. I have used a led and phototransistor to make optical sensors for monitoring vacuum pump rotation in spectrometers. That is a much worse environment than his use would be, and they work reliably for years.
I moved away from optical switches because of the small sensor distance required. I found that the sensor needed to be with in .3 mm, which is too close for my needs. I need a sensor that is about 3-6 mm from the switch.
Sorry, I forgot about these IR distance sensors. If you have the right reflective surface they can go quite far ... about 60 inches. And there are others from Sharp with closer ranges.
There is also the photo-interrupter style of sensor where the led is on one side and the phototransistor on the other side of a disk, pulley, or toothed gear. I have used a commercially available unit on a chain sprocket to rotate and stop an item at fixed positions by counting the sprocket teeth, and one I made to sense that a pump was turning by having the pulley spokes interrupt the IR beam. The pump rotation sensor led/phototransistor were separated by about 2 inches.
Ok, I have received all of my hardware and I have been spending time with getting Spin to toggle an LED with the touch of a button. After further thought of moving the stepper a set number of steps, I think it will be more reliable to limit the extent of the stepper's rotation via a limit switch (optical?) rather than using a set number of steps, ie 66,66, & 67 step sequence that we discussed earlier. The limit switch could be a hall-effect or optical as long as the sensor has a narrow detection region such that a magnet or reflector can trip the switch within +/- 2-3 mm of a given position.
I will be experimenting with my new Cherry hall-effect switch later today.
I look forward to hearing more about your progress.
To begin with, you can try to drive the stepper motor controller's three inputs with 3.3volts from the Propeller. That should not damage the Propeller i/o as there is an LED and a 270 ohm current limiting resistor. If nothing happens, you may have to insert a chip to bump up the voltage to 5.0 volts to deliver to the stepper motor controller. I am thinking an IC, such as a 74HC04 that is driven at 5 volts. The 74HC04 will output 20ma each unit.. avoid the 74LS04 as it outputs much less.
The 74HC04 also adds a layer of protection between the Propeller and the device if you have long wires that might get shorted. The 74xx04 would suffer damage, not the Propeller i/o. That may not be the case here as you seem to intend to put the Propeller and the stepper motor controller and the power supply in one case.
Since it has 6 inverters, you can wire them in pairs and not have any inversion.. just the 3 lines you require - Step, Enable, and Direction. Enable is not really required as the default is always Enabled. Of course, you could use just one inverter and change the default to NOT Enabled. If you don have left over inverters, the inputs should be tied high, so that they don't consume extra power.
I suspect the Hall Effect Sensor is the best choice for you. The problem with LEDs sensors in art work, there is the possibility of some tiny LED light showing up where you don't want it.
How do I wire a 74HC04 to a propeller if the 3.3 volts is not enough? Not usre what an inverter does.
Here is what I assuming for the wiring of the hardware:
24 VDC V+ to controller +V
24 VDC COM to controller GND
Controller A+ and A- to stepper blue and yellow. (I determined that they are a pair by connecting them and finding the stepper harder to turn)
Controller B+ and B- to stepper red and green
Not sure about how to connect the QuickStart to the controller
To test the hall-effect on a breadboard, I assume that:
VCC connects to 6 VDC + with a 400 ohm resistor and LED in series ( gives 15 ma)
Output connect to 6 VDC +
Ground connects to 6 VDC -
Are my wiring assumptions correct? I don't want to fry anything.
I may be getting too far ahead since I am still learning SPIN. Thanks for your patience
I have successfully simulated the QuickStart so that when Pad 0 is pressed, an LED flashes to simulate the stepper motor has begun moving. As I mentioned earlier, I have decided to terminate the stepper movement with a limit switch rather than after a set number of steps.So, I stop the stepper in my simulation by pressing Pad 7. The program runs in a continuous loop waiting for Pad 0 to be pressed again which repeats the cycle.
I think I am now at a point where I would like to connect the stepper/driver to the QuickStart and begin experimenting with step rates and acceleration. I have looked on Parallax's OBEX exchange with the hope of finding an object that would allow me to control a stepper motor, but I had no luck. I suspect a method needs to be written that would include passed parameters such as 1) initial step rate, 2)final step rate, 3)time between initial and final. Any thoughts?
Also, I need help in connecting the hardware to the QuickStart.
I successfully tested the Cherry hall-effect switch. The switch is normally open and I am able to close it using a 5 mm dia rare earth magnet disc from as far as 5 mm from the switch. I plan to use the same type of switch to stop the stepper movement.
Okay, so the Cherry switch is within the right distance range, right?
Regarding the stepper motor controller...
It is highly unlikely that you would find an example in OBEX for control of one. There are OBEX objects that allow you to build your own stepper motor controller, but these are generally intended for less powerful steppers and a demonstration exercize.
Regarding your programing and connecting the stepper motor controller.. it is quite straightforward.
~~~~~~~
Do the following without any active power. Wiring should always be done when everything is Turned Off to avoid spurious forms of damage.
1. Hook up the stepper motor as instructed in documentation - 4 wires
2. Hook up the 24VDC power supply
3. Select 3 available i/o pins from the Propeller QuickStart for outputs to the plus side of Step, Enable, and Direction, and connect to the + side on the stepper motor controller inputs.
4. Connect the minus side of the Step, Enable, and Direction to the Propeller QuickStart ground, do not include the 24VDC ground at this point... complete electrical isolation.
5. Configure the various DIP switches -- half or full current, the actual current target at no more than 2.8 amps, and the size of the step from a full step to 1/256th (there are two ranges - one is binary fractions and the other is decimal fractions as the screws for CNC come in these alternatives)
6. Look at everything. Verify that polarity of all connections are correct.
7. Consider Programming the Propeller QuickStart with PropForth or TacyonForth if you want to bench test your delays and step rates in real time. Alternatively, there may be a Basic language for the Propeller that does real time programing.
OR set up a test program in SPIN that initially allows a touch switch to issue one step pulse. Have the Enable always on and the Direction always in one direction.
8. Determine where you are getting your +5VDC for the Propeller Quick Start from. Initially you can use the computer's USB port for bench work, but later you will have to convert the +24 to +5 and Pololu does mention adding a big capacitor to their tiny board to prevent electrical damage when the input is as high as +24VDC.
9. Select an input pin for the Cherry proximity sensor. Since this is an open-collector, you will need a 1Kohm pull up to 3.3volts next to the i/o pin. The pin will sense High as No trigger, Low as trigger.
Later you can add to the program to turn Enable on and off and to change Direction. You cannot change step-size from the inputs provided by the Propeller, that is set in the DIP switch bank.
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The main thing here is to get all your connections right and to have an extremely simple program to prove that the electrical pulses are doing what they are supposed to do. The purpose is to not get tangled in confusion of whether it is the hardware and wiring are wrong OR the software is wrong. Having clear confirmation that your wiring configuration is right will make your software development much simpler.
At this point, you should be able to observe if any hum or noise that is inappropriate occur. There are two sources of potential trouble - [a] hum from the stepper motor itself, and hum and whines from the stepper motor controller. (I presume the power supply will be quiet.)
Noise from the stepper motor may be amplified by how the motor is mounted. If you create a 'sounding board' your project with have more noise. In some cases, a good motor mount and a sound proof box packed with fiberglass insulation can make the motor extremely quiet. And the motor might need to be mounted on rubber grommets to avoid noise being transferred to framework.
Noise from the stepper motor controller may be dependent on the size of the step, the width of the trigger pulse, and the rate of the trigger pulse. Since you want to vary the factors for the sake of your sculpture, I'd personally use PropForth to get all the timing right and to be assured the noise levels are the lowest, but it really is up to you which computer language you want. At this point, I am just hoping that you have a quiet stepper motor controller as the issues on how to fix a noisy one are numerous and complex.
Yes, you can create a nice program in SPIN that will have a big list of Constants to tweak and can go that way. If you want to discuss programing ins SPIN, maybe you should start another thread in the Propeller 1 forum and get support from people that are more expert than myself.
From what I read, the stepper motor controller requires a STEP pulse of greater than 10 micro-seconds. That is just about the only hard limit you have. If you want to increase the step rate, the issue is whether you want a linear increase or an exponential increase. And of course, do you really want to start with this complexity or just get the program to first work at a steady step rate and assure the mechanical performance with as stepper is working with the mechanics of the sculpture.
In other words, if you try to do too many things at one time, you may never get what you want. So you may have to build your program in tiny steps toward the ideal movement you want.
- The QuickStart schematic shows that the odd numbered pins are connected to 3.3 v, but the even numbered pins are not? Does this mean that I should use 3 odd numbered pins to connect to the plus side terminals on the stepper controlller?
-If the odd pins are what I need to connect to the plus terminals on the stepper controller, I suppose pins 1,3 & 5 will work for that? What are the pins for that are labeled /USB_PWR_EN, XI, /RTS, & /CTS?
- It appears that the even pins (0-26) are not connected to anything? If so, are they just there for jumping purposes?
- Is the plus side of Direction the same as PUL+ on the stepper controller?
- Is it correct to use pin 40 for the QuickStart ground?
- Do I want half or full current configuration?
-On #9 on your step list, is the VCC on the Cherry switch connected to pin 39 (3.3v) and the output connected to an odd pin with a 1Kohm in series?
-I assume that we are attempting to drive the stepper with the QuickStart's 3.3 v, but may need to add a component to raise the voltage to 5v?
Although I am ok with using the USB port to power the QuickStart during experimentation, I would like to acquire the necessary hardware to power it from the 24 VDC ps. Can you remind me of what Pololu board will be adequate?
I am perfectly fine with using PropForth for the programming. I totally agree that we need to keep it simple at first to be able to discern between hardware and software problems.
Frankly, I don't think you clearly understand what each of the QuickStart interface pins are wired to.
Be extremely careful at this point .. because wrong wiring can cause sudden and complete damage.
I will have to reread the QuickStart documentation to help you through this, but a simple summary of the Propeller chip is a good place to start.
The Propeller is a 40 pin DIP or a 44 pin surface mount device. There are always 32 i/o pins. The rest of the pins are special uses. There are a pair that go to the Crystal, there is one for a Reset and it has another related pin to determine what to do with a brown out. Then the 40 pin DIP has 2 ground and 2 V+ that must all be connected to assure the Propeller is not damaged. The 44 pin surface mount has another 2 grounds and another 2 V+. Additionally, the QuickStart has a USB to Serial chip that is your programing port.
You might read the introductory pages of the Propeller Manual to get some idea of what typical set up is suppose to be. The QuickStart might be a bit confusing.
On the Quick Start, there are two rather large interfaces. One is intended to use a socket and allow the Quick Start Protoboard to plug into it. The other is intended to allow you to attach wires directly to the board. The Quick Start documentation explains in detail which each of these actually does. These can be hazardous as a lot of different items are neighbors.
And I don't think your all odd pin solution is going to work right. So don't go ahead with it unless I say okay.
Pins 0-26 do have purposes... you just don't understand what's going on. Yes you need to understand all the pins and all the labels on the board to properly use it... including /USB_Power_EN, XI, /RTS, & /CTS. But these last items are related to the USB interface and a couple of pin on the Propeller that send and receive RS232 from the USB to Serial converter.
/USB_Power_En likely means a low signal will enable the USB port. and a high will turn it off
/RTS likely means a low indicates a Ready to Send (used with serial communications)
/CTS likely means a low indicates a Clear to Send (used also with serial commuincaions)
XI Well, I am not sure, but I am sure I can find out.
On the Stepper Motor Controller.
The + side of the PUL is NOT the same as the + side of the Direction on the stepper controller. They are independent.
The stepper controller has 3 independent LEDs internally that are lit with the entirely separate circuits. So the PUL, the Direction, and the Enable all have their own isolated + and - , also these inputs will NOT tolerate a reverse voltage and voltage is limited to +5 volts max -- but I think that +3.3 volts can safely drive the LEDs.
Half-current or full-current. It is an interesting feature. The half-current is intended for safe testing. When you feel you have everything right, you switch to full-current.
As it stands, yes - I am trying to see if the LEDs in the Stepper Motor Controller are sensitive enough to operate at 3.3volts, and do not need 5.0 volts. But the 3.3 volts needs to come from i/o pins in order to be controlled in software, not from the +3.3 volt power supply pins that will not respond to software.
~~~~~~~~~~~~~~~~~~~~~~~~~
I will repeat what I want in i/o. You will use ONLY 4 pin of i/o and alls have 4 connections to QuickStart ground. The Propeller has 32 i/o available.
The Propeller will provide 3 pins as output. Each of this will provide 3.3v when high, and 0.0 volts when low. Those three output pins will go one each to the +ENABLE, +PUL, and +DIR.
The -ENABLE, -PUL, and -DIR will go tho the GROUND on the QuickStart board
The abouve are all 3 outputs complete and then the Cherry Switch uses one i/o pin as an Input where a high is Inactive, and a low is active.
To wire the Cherry Switch it requres 4.5 to 24 VDC power (it has an internal regulator). I'd prefer that you provide VCC at +5 power to it as +24 will make it run hotter. The pull up resistor will NOT go to VCC as the Propeller tolerates only 3.3v on is inputs.
And then there is one wire left over that is the input signal. It goes to the input pin (of your choice) on the Propeller. To help the Open Collector, that input pin has a 1 K ohm resistor connected to 3.3v power. This is a pull up resistor configuration.
And so, you are using merely 4 i/o out of the 32 available i/o on the Propeller QuickStart board. But you might want to avoid the 8 i/o addtacted to the blue LEDs, the 8 i/o attached to the touch swithces, the 2 i/o attached to the USB device, and the 2 i/o attached to the ROM. So there are really only 12 i/o pins that are not assigned.
If labels and documents are not enough, you may have to use a VOM and track which are power outputs, which are ground, and which are other things.
YOU really need to mainly identify the 3.3v supply, the 5.0v supply, the ground, the Reset, and all 32 i/o pins on the QuickStart.
But you will only use 4 i/o pins (3 outputs, 1 input), the V3.3, maybe the V5.0, and certainly the ground.
Thanks for your patience. As you can see, I am quite ignorant to all of this microchip board and stepper/controller configuration. I will read the QuickStart docs more thoroughly and hopefully get a better understanding, albeit with my limited electronics background. I will indeed be careful during my wiring, maybe to an annoying point on your part, before I energize anything.
- Is the plus side of Direction the same as PUL+ on the stepper controller? My question was incorrect. When you instructed me to:
3. Select 3 available i/o pins from the Propeller QuickStart for outputs to the plus side of Step, Enable, and Direction, and connect to the + side on the stepper motor controller inputs.
I meant to ask are the Step terminals the same as the PUL teminals.
NOTE _ I corrected the below as I didn't understand your question at first.
Are the Step terminals the same as the PUL terminals? (Yes, I guess I am getting sloppy with my writing.)
Electrically, the Step, Direction, and Enable are all the same configuration... one LED and a 270 ohm resistor to protect the LED from excess current when used at +5 volts or less.
Are the Step, Direction, and Enable all wired together. Nope. They are just three entirely separate sets of one LED and one resistor in series.
~~~~~~~~~
It is not easy to get all this done over the internet. I write everything reread, re-edit and often repeat that process several times. I am committed to helping you have a good outcome. But, you will eventually have to know something about electricity, solid-state electronics, and programing micro-controllers.
You have already learned quite a bit, so hang in there. I have tried to be selective in the links to supplemental reading so you are not buried in literature. But the links are important as they often have an excellent presentation of something that would take me a lot of time to recreate.
You really need to focus on the Propeller Manual and the QuickStart documents... all of them. I also provide a good link for the Stepper Motor Controller documentation that is probably better than what you were sent. That is useful. The seller provided you with info on how to wire the right color coil wires to the stepper motor controller.
Later we can discuss adding a length of cable so that the box of electronics is away from the sculpture, but now you should use short wires for a simple bench test to prove configuration.
In a worse case, you might damage one of the i/o pins on the Propeller. I am pretty sure you cannot damage the LEDs on the stepper motor controller if your voltage is +5 or less (diodes don't conduct in reverse). Reversing the 24V power supply connections would likely destroy a lot.
If you do damage one i/o pin on the Propeller, you still have 31 others to use (maybe just 27 as 4 are really needed for your programing and ROM).
So just make darned sure the 24VDC is wired right and use some 120VAC extension cord wire or something as heavy. It would be best if plus was RED (or some other color) and minus was BLACK. More amps requires bigger wire at any voltage, 5 amps should have 18 gauge or larger.
Thanks for the clarification. You refer to 3 independent internal LEDs on the controller. I find only 2 LED on my controller, but they are marked PWR/ALARM. If you are referring to 3 LED inside the controller that can't be seen, what is their purpose? From what I have read the only purpose of an LED is to indicate power flow.
Ok, it looks like pins pins 0-7 are used by the touchpads, and pins 16-23 are used by the touchpad LEDs. Using a meter, I found 4.77 v on pin 40 (It is marked as Vin). Since my QuickStart uses the P8X32A-Q44 chip, the schematic shows that chips pin 37 is the Reset (RESn) , pin 39 for the ground, 3.3v at pin 38. So, I think the 4 pins that are needed could be selected from pins 8-15 & 24-27. As for the 3 outputs and 1 input, wouldn't that be defined in PropForth by setting the direction and input/output registers?
PMJI but based on the OP, I would simply recommend something like the Animatics Smart Motor or at least a more ready-made solution such as the PIC-servo from www.jrkerr.com
Disregard that last question. I just realized that the LED's purpose is mainly for its diode purpose and not for illumination.
Nope, it is for its optical isolation. The fact is very simple... these LEDS are inside a chip case and you can not see them. They are there, they generate light that the phototransistor that is paired with them can see, but they look like a regular 6 pin DIP.
a. Setting up your 4 i/o connections - 3 output from the Propeller and 1 input to the Propeller
b. Adapting devices that are NOT intended for the Propeller's 3.3 volt i/o system to safe use.
Regarding b.
1. The outputs are less of a problem than the inputs as they will always output just 3.3v.
>>> If you don't require more than 20 ma current (such as a short-circuit), they will work fine.
>>> If you need more power in terms of a higher voltage and/or a higher current, there are a variety of good solutions.
2. The inputs need to see no more than 3.3 volts.
>>> So pull-up resistors attached to an input should NOT exceed 3.3 volts, even though you will find examples of Open Collector wiring that only show +5.0 volts
>>> In some cases users have found that a +5.0 volt logic can be dropped with a 3300 ohm or larger resistor in series with the i/o pin. This is NOT a pull-up or pull-down configuration; it is a direct drive. Do not confuse it with the Open Collector Pull-up configuration.
PMJI but based on the OP, I would simply recommend something like the Animatics Smart Motor or at least a more ready-made solution such as the PIC-servo from www.jrkerr.com
Regards,
Mickster
The above may work, or maybe not -- but all the hardware has already been bought.
Ok, it looks like pins pins 0-7 are used by the touchpads, and pins 16-23 are used by the touchpad LEDs. Using a meter, I found 4.77 v on pin 40 (It is marked as Vin). Since my QuickStart uses the P8X32A-Q44 chip, the schematic shows that chips pin 37 is the Reset (RESn) , pin 39 for the ground, 3.3v at pin 38. So, I think the 4 pins that are needed could be selected from pins 8-15 & 24-27. As for the 3 outputs and 1 input, wouldn't that be defined in PropForth by setting the direction and input/output registers?
Okay, this is a lot of progress. Previously you thought Pin 40 was Ground, but it is actually +4.77 (which is roughly a +5) and can be used to power the Cherry Proximity Switch.
You have found the true Ground at Pin 39. And +3.3V at Pin 38, which can be used to pull up the input for the Cherry's Open Collector "output"
You do indeed set direction in whatever software you are using. If you want to use PropForth, I recommend you load a copy of V5.0 into the EEPROM and learn a bit about blinking LEDs. I will try to help you with it.
A Review Summary.
1. The Propeller has 32 i/o pins with 2 used for a programming serial port and 2 used to connect to an EEPROM. So actually 28 are more generally available.
2. Notation in software usually refers to all 32 as each of the 32 bits refer directly to one i/o pin in Propeller's machine code.
3. An i/o MAP is an important reference and if you don't have a good one provided it is always important to create your own reference.
i/o MAP for the Quick Start ( confirmed in QuickStart documents and schematic)
0 - 7 Touchpads as inputs
8 -15 (uncommitted -- available for general use as inputs or outputs)
16-23 LEDs as indicator outputs. (These are not directly related to the Touchpads and can be used for other independent purposes.)
24-27 (uncommitted --available for general use as inputs or outputs)
28-29 EEPROM that stores the program
30-31 Serial (RS232) Rx and Tx used for downloading Programs and communication to a desktop computer
Reverse polarity to the Cherry Proximity switches VCC and GND power will immediately destroy it... be careful.
Since 24-27 is a row of 4 pins, you might prefer to use those and leave the 8-15 unused at this time. There are times that a full 8 bits come in handy, like in video generation.
I have several old Propeller boards with damaged i/o in odd locations. For many projects, you can just select a different i/o pin in software if one is damaged. Such old board generally get used first for bench and experimental work as I worry less about damage and the loss of a board.
Do you have previous experience with Forth? If not, I guess I will have to get you up to speed. PropForth v5.0 is something I personally use, but I started out with no experience in Forth and first read "Starting Forth" by Brodie and using a mainstream Forth on the desktop to work through the examples.
Both PropForth and Tachyon Forth are non-standard Forth because of the small microcontroller and the 8 parallel processors. You only need to write a few words and to use one Cog to get your project working in Forth. So learning all and everything about PropForth could become a distraction.
I want to find a way to get you up to speed that is not too complicated or a big distraction.
Okay, I have confirmed the i/o map listed in the above thread. At this point, I am hoping you have you build a bench test without soldering wires directly to the QuickStart. You may want to add soldered sockets to use with a temporary build. That is okay. I am just trying to avoid the potential for damage of soldering and unsoldering wires directly to the board.
You will be looking for more grounds and maybe more 3.3v sources - J4, J5, J6, and J7 offer additional 3.3V and Ground connections. You may or may not want to solder some sort of socket or connector to J4, J5, J6, and J7 or just solder wires directly to the holes.
You may have to get a bit creative to have the 1K resistor and the Cherry output wire share the connection to one Propeller input.
I am assuming that the bench work will all be temporary solderless connections. At times these can be loose and really annoying. Try to develop your technique to get good stable connections. Finding the right size wire helps a great deal. I use the 4 wire telephone wire that is solid copper and used to install normal telephone installations. If you can buy or salvage a couple of yards of it from a hardware store or somewhere, that is about all you need.
One idea is to use a 1K resistor that has the Cherry output wire soldered to one end. The Cherry wires may be too big for the sockets on the board. So solder bits of smaller wire to the ends to plug into the QuickStart.
Then the resistor will plug into the 3.3v that is socketed at one end for the pull up 3.3V, and both the Cherry and the resistor can plug into the right input socket at the other end. This presumes that have a 40 pin 2x20 socket on the Propeller QuickStart. if it doesn't already have one installed, solder it in place.
Why are there the two 40 Pin, 2x20 set ups and only one with a socket? The unsocketed one allow you to directly attach wires.
At some point in the future, the QuickStart board will need to be adapted to run independent of the USB connection. To do so, you will have to provide an outside +5V. Did you buy the Pololu device to convert +24VDC to +5VDC?
When you get all your bench wiring sorted out and actually have PropForth installed, you will want a few words immediately.
We have two sides to test --- Input and Output.
~~~~~~~~~~~~~~~~~~~~~~~~
Output is easier to start with...
So first create six Forth words
a. Enable
b. Disable
c. Clockwise
d. Counter-clockwise
e. Pulse on
f. Pulse off
Each pair with identify and I/O pin as an Output and generate either a High or Low.
Pulse on and Pulse off with a 10 microsecond or longer pause between the two can create another word Step.
Then you can refine these words into another word, let's call Start
Start would just activate Enable and Choose your prefered direction.
After that you could just type Step from the keyboard and get exactly one Step of motor rotation.
If that is too small to see, you could just type
Step Step Step Step Step Step Step Step Step Step (return) to get 10 Steps and 18 degrees of rotation.
Next you may want to figure out how to create a word that with accept a number and do that many steps, say Steps.
So you could type
10 Steps to get 18 degrees
66 Steps to get near 120 degrees
Try changing direction and try disables. This will verify that the hardware set up is right and working with the software. And THAT is why I personally prefer Forth. It is extremely easy to use to verify you are doing things right or wrong.
~~~~~~~~~~~~~~
Then the Input......
Once you got all that working well, be can deal with the Cherry Proximity Sensor and how to create words for Input. Testing an Input requires a bit more knowledge as you will have to have a loop looking for a change in the state of the input from a High to a Low.
First just have it report a Hi or Low
Then create an endless loop with a bit of delay, say 50 milla-seconds.
Create a name for the loop and when activate the name, you can fool with a magnet and see changes from High to Low and back again.
I have downloaded the paper you authored titled "A guide to Forth on the Parallax Propeller for the complete beginner", but then started reading Brodie's "Starting Forth" online paper. My hope is to build somewhat of a foundation to understand what code you may provide.
Good suggestions on the bench test setup. I plan on working on that later today.
I do worry that I have dragged you into a personal preference for Forth. If you don't like Forth, everything can be done in SPIN or C or maybe in an interactive Basic.
If you dislike PropForth, there is also TachyonForth.
What I am saying is the Propeller has lots of programing alternatives and I don't really want to burden you with what I prefer. It is more about what you want to learn and do.
Nonetheless, using PropForth V5.0 might just make this come together very quickly if you feel comfortable with it.
Above all, you don't NOT have to become an advanced Forth user. All you are using is ONE Cog.
My primary immediate need is to incorporate the use of a stepper motor with my kinetic sculptures .In doing so, I think it is helpful to maintain as much continuity with you since you are most familiar with my efforts and my abilities. Your proficiency with propforth will be a useful skill when i get to the programming portion of my project. . But of equal importance, through this effort,I hope to learn more about using microprocessors in future projects. Since I am beginning from scratch regarding microprocessor programming, it makes sense to me to choose a language that has the greatest potential for growth. From what i have read on the forth language, I think that forth is the best language on which to invest my time learning.
My primary immediate need is to incorporate the use of a stepper motor with my kinetic sculptures .In doing so, I think it is helpful to maintain as much continuity with you since you are most familiar with my efforts and my abilities. Your proficiency with propforth will be a useful skill when i get to the programming portion of my project. . But of equal importance, through this effort,I hope to learn more about using microprocessors in future projects. Since I am beginning from scratch regarding microprocessor programming, it makes sense to me to choose a language that has the greatest potential for growth. From what i have read on the forth language, I think that forth is the best language on which to invest my time learning.
PropForth and TachyonForth don't have many of the words of an ANSI standard Forth and while it is not really important to using a micro-controller such as the Propeller.. it caused a huge debate on these forums.
PropForth and TachyonForth DO have a lot of special features just for the Propeller 1. And maybe for the Propeller 2 soon.
So learning with GForth at first might be more comfortable for you. If you want to get started at the same time with Prop Forth, just learn to turn on and off or the LEDs on the QuickStart from your computer keyboard. That will give you an idea of its power. If you were to connect a relay to the same output as the LEDs, you could turn on and off anything that the relay is connected too.. like your 120VAC lighting in your home, or your TV or whatever.
A reminder that I will need to have to 2 Cherry switches in the circuit. The second switch will terminate the stepper sequence rather than have the program stop the stepper after a defined number of steps. Since 3 output pins and 2 input pins are needed, maybe I use 5 pins from the uncommitted block of pins 8-15?
Comments
I was a bit surprised tomboardman passed on the optical sensors in favor of hall effect switches though. I have used a led and phototransistor to make optical sensors for monitoring vacuum pump rotation in spectrometers. That is a much worse environment than his use would be, and they work reliably for years.
http://www.trossenrobotics.com/c/robot-IR-sensors.aspx
http://www.jameco.com/webapp/wcs/stores/servlet/ProductDisplay?langId=-1&storeId=10001&productId=2136462&catalogId=10001&CID=MERCH
http://www.parallax.com/dl/docs/prod/acc/SharpGP2D12Snrs.pdf
I will be experimenting with my new Cherry hall-effect switch later today.
To begin with, you can try to drive the stepper motor controller's three inputs with 3.3volts from the Propeller. That should not damage the Propeller i/o as there is an LED and a 270 ohm current limiting resistor. If nothing happens, you may have to insert a chip to bump up the voltage to 5.0 volts to deliver to the stepper motor controller. I am thinking an IC, such as a 74HC04 that is driven at 5 volts. The 74HC04 will output 20ma each unit.. avoid the 74LS04 as it outputs much less.
The 74HC04 also adds a layer of protection between the Propeller and the device if you have long wires that might get shorted. The 74xx04 would suffer damage, not the Propeller i/o. That may not be the case here as you seem to intend to put the Propeller and the stepper motor controller and the power supply in one case.
Since it has 6 inverters, you can wire them in pairs and not have any inversion.. just the 3 lines you require - Step, Enable, and Direction. Enable is not really required as the default is always Enabled. Of course, you could use just one inverter and change the default to NOT Enabled. If you don have left over inverters, the inputs should be tied high, so that they don't consume extra power.
I suspect the Hall Effect Sensor is the best choice for you. The problem with LEDs sensors in art work, there is the possibility of some tiny LED light showing up where you don't want it.
Here is what I assuming for the wiring of the hardware:
24 VDC V+ to controller +V
24 VDC COM to controller GND
Controller A+ and A- to stepper blue and yellow. (I determined that they are a pair by connecting them and finding the stepper harder to turn)
Controller B+ and B- to stepper red and green
Not sure about how to connect the QuickStart to the controller
To test the hall-effect on a breadboard, I assume that:
VCC connects to 6 VDC + with a 400 ohm resistor and LED in series ( gives 15 ma)
Output connect to 6 VDC +
Ground connects to 6 VDC -
Are my wiring assumptions correct? I don't want to fry anything.
I may be getting too far ahead since I am still learning SPIN. Thanks for your patience
I think I am now at a point where I would like to connect the stepper/driver to the QuickStart and begin experimenting with step rates and acceleration. I have looked on Parallax's OBEX exchange with the hope of finding an object that would allow me to control a stepper motor, but I had no luck. I suspect a method needs to be written that would include passed parameters such as 1) initial step rate, 2)final step rate, 3)time between initial and final. Any thoughts?
Also, I need help in connecting the hardware to the QuickStart.
I successfully tested the Cherry hall-effect switch. The switch is normally open and I am able to close it using a 5 mm dia rare earth magnet disc from as far as 5 mm from the switch. I plan to use the same type of switch to stop the stepper movement.
Regarding the stepper motor controller...
It is highly unlikely that you would find an example in OBEX for control of one. There are OBEX objects that allow you to build your own stepper motor controller, but these are generally intended for less powerful steppers and a demonstration exercize.
Regarding your programing and connecting the stepper motor controller.. it is quite straightforward.
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Do the following without any active power. Wiring should always be done when everything is Turned Off to avoid spurious forms of damage.
1. Hook up the stepper motor as instructed in documentation - 4 wires
2. Hook up the 24VDC power supply
3. Select 3 available i/o pins from the Propeller QuickStart for outputs to the plus side of Step, Enable, and Direction, and connect to the + side on the stepper motor controller inputs.
4. Connect the minus side of the Step, Enable, and Direction to the Propeller QuickStart ground, do not include the 24VDC ground at this point... complete electrical isolation.
5. Configure the various DIP switches -- half or full current, the actual current target at no more than 2.8 amps, and the size of the step from a full step to 1/256th (there are two ranges - one is binary fractions and the other is decimal fractions as the screws for CNC come in these alternatives)
6. Look at everything. Verify that polarity of all connections are correct.
7. Consider Programming the Propeller QuickStart with PropForth or TacyonForth if you want to bench test your delays and step rates in real time. Alternatively, there may be a Basic language for the Propeller that does real time programing.
OR set up a test program in SPIN that initially allows a touch switch to issue one step pulse. Have the Enable always on and the Direction always in one direction.
8. Determine where you are getting your +5VDC for the Propeller Quick Start from. Initially you can use the computer's USB port for bench work, but later you will have to convert the +24 to +5 and Pololu does mention adding a big capacitor to their tiny board to prevent electrical damage when the input is as high as +24VDC.
9. Select an input pin for the Cherry proximity sensor. Since this is an open-collector, you will need a 1Kohm pull up to 3.3volts next to the i/o pin. The pin will sense High as No trigger, Low as trigger.
Later you can add to the program to turn Enable on and off and to change Direction. You cannot change step-size from the inputs provided by the Propeller, that is set in the DIP switch bank.
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The main thing here is to get all your connections right and to have an extremely simple program to prove that the electrical pulses are doing what they are supposed to do. The purpose is to not get tangled in confusion of whether it is the hardware and wiring are wrong OR the software is wrong. Having clear confirmation that your wiring configuration is right will make your software development much simpler.
At this point, you should be able to observe if any hum or noise that is inappropriate occur. There are two sources of potential trouble - [a] hum from the stepper motor itself, and hum and whines from the stepper motor controller. (I presume the power supply will be quiet.)
Noise from the stepper motor may be amplified by how the motor is mounted. If you create a 'sounding board' your project with have more noise. In some cases, a good motor mount and a sound proof box packed with fiberglass insulation can make the motor extremely quiet. And the motor might need to be mounted on rubber grommets to avoid noise being transferred to framework.
Noise from the stepper motor controller may be dependent on the size of the step, the width of the trigger pulse, and the rate of the trigger pulse. Since you want to vary the factors for the sake of your sculpture, I'd personally use PropForth to get all the timing right and to be assured the noise levels are the lowest, but it really is up to you which computer language you want. At this point, I am just hoping that you have a quiet stepper motor controller as the issues on how to fix a noisy one are numerous and complex.
Yes, you can create a nice program in SPIN that will have a big list of Constants to tweak and can go that way. If you want to discuss programing ins SPIN, maybe you should start another thread in the Propeller 1 forum and get support from people that are more expert than myself.
From what I read, the stepper motor controller requires a STEP pulse of greater than 10 micro-seconds. That is just about the only hard limit you have. If you want to increase the step rate, the issue is whether you want a linear increase or an exponential increase. And of course, do you really want to start with this complexity or just get the program to first work at a steady step rate and assure the mechanical performance with as stepper is working with the mechanics of the sculpture.
In other words, if you try to do too many things at one time, you may never get what you want. So you may have to build your program in tiny steps toward the ideal movement you want.
- The QuickStart schematic shows that the odd numbered pins are connected to 3.3 v, but the even numbered pins are not? Does this mean that I should use 3 odd numbered pins to connect to the plus side terminals on the stepper controlller?
-If the odd pins are what I need to connect to the plus terminals on the stepper controller, I suppose pins 1,3 & 5 will work for that? What are the pins for that are labeled /USB_PWR_EN, XI, /RTS, & /CTS?
- It appears that the even pins (0-26) are not connected to anything? If so, are they just there for jumping purposes?
- Is the plus side of Direction the same as PUL+ on the stepper controller?
- Is it correct to use pin 40 for the QuickStart ground?
- Do I want half or full current configuration?
-On #9 on your step list, is the VCC on the Cherry switch connected to pin 39 (3.3v) and the output connected to an odd pin with a 1Kohm in series?
-I assume that we are attempting to drive the stepper with the QuickStart's 3.3 v, but may need to add a component to raise the voltage to 5v?
Although I am ok with using the USB port to power the QuickStart during experimentation, I would like to acquire the necessary hardware to power it from the 24 VDC ps. Can you remind me of what Pololu board will be adequate?
I am perfectly fine with using PropForth for the programming. I totally agree that we need to keep it simple at first to be able to discern between hardware and software problems.
Be extremely careful at this point .. because wrong wiring can cause sudden and complete damage.
I will have to reread the QuickStart documentation to help you through this, but a simple summary of the Propeller chip is a good place to start.
The Propeller is a 40 pin DIP or a 44 pin surface mount device. There are always 32 i/o pins. The rest of the pins are special uses. There are a pair that go to the Crystal, there is one for a Reset and it has another related pin to determine what to do with a brown out. Then the 40 pin DIP has 2 ground and 2 V+ that must all be connected to assure the Propeller is not damaged. The 44 pin surface mount has another 2 grounds and another 2 V+. Additionally, the QuickStart has a USB to Serial chip that is your programing port.
You might read the introductory pages of the Propeller Manual to get some idea of what typical set up is suppose to be. The QuickStart might be a bit confusing.
On the Quick Start, there are two rather large interfaces. One is intended to use a socket and allow the Quick Start Protoboard to plug into it. The other is intended to allow you to attach wires directly to the board. The Quick Start documentation explains in detail which each of these actually does. These can be hazardous as a lot of different items are neighbors.
And I don't think your all odd pin solution is going to work right. So don't go ahead with it unless I say okay.
Pins 0-26 do have purposes... you just don't understand what's going on. Yes you need to understand all the pins and all the labels on the board to properly use it... including /USB_Power_EN, XI, /RTS, & /CTS. But these last items are related to the USB interface and a couple of pin on the Propeller that send and receive RS232 from the USB to Serial converter.
/USB_Power_En likely means a low signal will enable the USB port. and a high will turn it off
/RTS likely means a low indicates a Ready to Send (used with serial communications)
/CTS likely means a low indicates a Clear to Send (used also with serial commuincaions)
XI Well, I am not sure, but I am sure I can find out.
On the Stepper Motor Controller.
The + side of the PUL is NOT the same as the + side of the Direction on the stepper controller. They are independent.
The stepper controller has 3 independent LEDs internally that are lit with the entirely separate circuits. So the PUL, the Direction, and the Enable all have their own isolated + and - , also these inputs will NOT tolerate a reverse voltage and voltage is limited to +5 volts max -- but I think that +3.3 volts can safely drive the LEDs.
Half-current or full-current. It is an interesting feature. The half-current is intended for safe testing. When you feel you have everything right, you switch to full-current.
As it stands, yes - I am trying to see if the LEDs in the Stepper Motor Controller are sensitive enough to operate at 3.3volts, and do not need 5.0 volts. But the 3.3 volts needs to come from i/o pins in order to be controlled in software, not from the +3.3 volt power supply pins that will not respond to software.
~~~~~~~~~~~~~~~~~~~~~~~~~
I will repeat what I want in i/o. You will use ONLY 4 pin of i/o and alls have 4 connections to QuickStart ground. The Propeller has 32 i/o available.
The Propeller will provide 3 pins as output. Each of this will provide 3.3v when high, and 0.0 volts when low. Those three output pins will go one each to the +ENABLE, +PUL, and +DIR.
The -ENABLE, -PUL, and -DIR will go tho the GROUND on the QuickStart board
The abouve are all 3 outputs complete and then the Cherry Switch uses one i/o pin as an Input where a high is Inactive, and a low is active.
To wire the Cherry Switch it requres 4.5 to 24 VDC power (it has an internal regulator). I'd prefer that you provide VCC at +5 power to it as +24 will make it run hotter. The pull up resistor will NOT go to VCC as the Propeller tolerates only 3.3v on is inputs.
And then there is one wire left over that is the input signal. It goes to the input pin (of your choice) on the Propeller. To help the Open Collector, that input pin has a 1 K ohm resistor connected to 3.3v power. This is a pull up resistor configuration.
And so, you are using merely 4 i/o out of the 32 available i/o on the Propeller QuickStart board. But you might want to avoid the 8 i/o addtacted to the blue LEDs, the 8 i/o attached to the touch swithces, the 2 i/o attached to the USB device, and the 2 i/o attached to the ROM. So there are really only 12 i/o pins that are not assigned.
If labels and documents are not enough, you may have to use a VOM and track which are power outputs, which are ground, and which are other things.
YOU really need to mainly identify the 3.3v supply, the 5.0v supply, the ground, the Reset, and all 32 i/o pins on the QuickStart.
But you will only use 4 i/o pins (3 outputs, 1 input), the V3.3, maybe the V5.0, and certainly the ground.
- Is the plus side of Direction the same as PUL+ on the stepper controller? My question was incorrect. When you instructed me to:
3. Select 3 available i/o pins from the Propeller QuickStart for outputs to the plus side of Step, Enable, and Direction, and connect to the + side on the stepper motor controller inputs.
I meant to ask are the Step terminals the same as the PUL teminals.
Are the Step terminals the same as the PUL terminals? (Yes, I guess I am getting sloppy with my writing.)
Electrically, the Step, Direction, and Enable are all the same configuration... one LED and a 270 ohm resistor to protect the LED from excess current when used at +5 volts or less.
Are the Step, Direction, and Enable all wired together. Nope. They are just three entirely separate sets of one LED and one resistor in series.
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It is not easy to get all this done over the internet. I write everything reread, re-edit and often repeat that process several times. I am committed to helping you have a good outcome. But, you will eventually have to know something about electricity, solid-state electronics, and programing micro-controllers.
You have already learned quite a bit, so hang in there. I have tried to be selective in the links to supplemental reading so you are not buried in literature. But the links are important as they often have an excellent presentation of something that would take me a lot of time to recreate.
You really need to focus on the Propeller Manual and the QuickStart documents... all of them. I also provide a good link for the Stepper Motor Controller documentation that is probably better than what you were sent. That is useful. The seller provided you with info on how to wire the right color coil wires to the stepper motor controller.
Later we can discuss adding a length of cable so that the box of electronics is away from the sculpture, but now you should use short wires for a simple bench test to prove configuration.
In a worse case, you might damage one of the i/o pins on the Propeller. I am pretty sure you cannot damage the LEDs on the stepper motor controller if your voltage is +5 or less (diodes don't conduct in reverse). Reversing the 24V power supply connections would likely destroy a lot.
If you do damage one i/o pin on the Propeller, you still have 31 others to use (maybe just 27 as 4 are really needed for your programing and ROM).
So just make darned sure the 24VDC is wired right and use some 120VAC extension cord wire or something as heavy. It would be best if plus was RED (or some other color) and minus was BLACK. More amps requires bigger wire at any voltage, 5 amps should have 18 gauge or larger.
Step is another way of saying Pulse.
Enable is just enable
Direction is just direction.
Some documents might use Pulse, and other might use Step.
Regards,
Mickster
Nope, it is for its optical isolation. The fact is very simple... these LEDS are inside a chip case and you can not see them. They are there, they generate light that the phototransistor that is paired with them can see, but they look like a regular 6 pin DIP.
http://www.electronics-tutorials.ws/blog/optocoupler.html
I am trying to focus on mainly TWO topics.
a. Setting up your 4 i/o connections - 3 output from the Propeller and 1 input to the Propeller
b. Adapting devices that are NOT intended for the Propeller's 3.3 volt i/o system to safe use.
Regarding b.
1. The outputs are less of a problem than the inputs as they will always output just 3.3v.
>>> If you don't require more than 20 ma current (such as a short-circuit), they will work fine.
>>> If you need more power in terms of a higher voltage and/or a higher current, there are a variety of good solutions.
2. The inputs need to see no more than 3.3 volts.
>>> So pull-up resistors attached to an input should NOT exceed 3.3 volts, even though you will find examples of Open Collector wiring that only show +5.0 volts
>>> In some cases users have found that a +5.0 volt logic can be dropped with a 3300 ohm or larger resistor in series with the i/o pin. This is NOT a pull-up or pull-down configuration; it is a direct drive. Do not confuse it with the Open Collector Pull-up configuration.
The above may work, or maybe not -- but all the hardware has already been bought.
Okay, this is a lot of progress. Previously you thought Pin 40 was Ground, but it is actually +4.77 (which is roughly a +5) and can be used to power the Cherry Proximity Switch.
You have found the true Ground at Pin 39. And +3.3V at Pin 38, which can be used to pull up the input for the Cherry's Open Collector "output"
You do indeed set direction in whatever software you are using. If you want to use PropForth, I recommend you load a copy of V5.0 into the EEPROM and learn a bit about blinking LEDs. I will try to help you with it.
A Review Summary.
1. The Propeller has 32 i/o pins with 2 used for a programming serial port and 2 used to connect to an EEPROM. So actually 28 are more generally available.
2. Notation in software usually refers to all 32 as each of the 32 bits refer directly to one i/o pin in Propeller's machine code.
3. An i/o MAP is an important reference and if you don't have a good one provided it is always important to create your own reference.
i/o MAP for the Quick Start ( confirmed in QuickStart documents and schematic)
0 - 7 Touchpads as inputs
8 -15 (uncommitted -- available for general use as inputs or outputs)
16-23 LEDs as indicator outputs. (These are not directly related to the Touchpads and can be used for other independent purposes.)
24-27 (uncommitted --available for general use as inputs or outputs)
28-29 EEPROM that stores the program
30-31 Serial (RS232) Rx and Tx used for downloading Programs and communication to a desktop computer
Reverse polarity to the Cherry Proximity switches VCC and GND power will immediately destroy it... be careful.
Since 24-27 is a row of 4 pins, you might prefer to use those and leave the 8-15 unused at this time. There are times that a full 8 bits come in handy, like in video generation.
I have several old Propeller boards with damaged i/o in odd locations. For many projects, you can just select a different i/o pin in software if one is damaged. Such old board generally get used first for bench and experimental work as I worry less about damage and the loss of a board.
Do you have previous experience with Forth? If not, I guess I will have to get you up to speed. PropForth v5.0 is something I personally use, but I started out with no experience in Forth and first read "Starting Forth" by Brodie and using a mainstream Forth on the desktop to work through the examples.
Both PropForth and Tachyon Forth are non-standard Forth because of the small microcontroller and the 8 parallel processors. You only need to write a few words and to use one Cog to get your project working in Forth. So learning all and everything about PropForth could become a distraction.
I want to find a way to get you up to speed that is not too complicated or a big distraction.
You will be looking for more grounds and maybe more 3.3v sources - J4, J5, J6, and J7 offer additional 3.3V and Ground connections. You may or may not want to solder some sort of socket or connector to J4, J5, J6, and J7 or just solder wires directly to the holes.
You may have to get a bit creative to have the 1K resistor and the Cherry output wire share the connection to one Propeller input.
I am assuming that the bench work will all be temporary solderless connections. At times these can be loose and really annoying. Try to develop your technique to get good stable connections. Finding the right size wire helps a great deal. I use the 4 wire telephone wire that is solid copper and used to install normal telephone installations. If you can buy or salvage a couple of yards of it from a hardware store or somewhere, that is about all you need.
One idea is to use a 1K resistor that has the Cherry output wire soldered to one end. The Cherry wires may be too big for the sockets on the board. So solder bits of smaller wire to the ends to plug into the QuickStart.
Then the resistor will plug into the 3.3v that is socketed at one end for the pull up 3.3V, and both the Cherry and the resistor can plug into the right input socket at the other end. This presumes that have a 40 pin 2x20 socket on the Propeller QuickStart. if it doesn't already have one installed, solder it in place.
Why are there the two 40 Pin, 2x20 set ups and only one with a socket? The unsocketed one allow you to directly attach wires.
At some point in the future, the QuickStart board will need to be adapted to run independent of the USB connection. To do so, you will have to provide an outside +5V. Did you buy the Pololu device to convert +24VDC to +5VDC?
When you get all your bench wiring sorted out and actually have PropForth installed, you will want a few words immediately.
We have two sides to test --- Input and Output.
~~~~~~~~~~~~~~~~~~~~~~~~
Output is easier to start with...
So first create six Forth words
a. Enable
b. Disable
c. Clockwise
d. Counter-clockwise
e. Pulse on
f. Pulse off
Each pair with identify and I/O pin as an Output and generate either a High or Low.
Pulse on and Pulse off with a 10 microsecond or longer pause between the two can create another word Step.
Then you can refine these words into another word, let's call Start
Start would just activate Enable and Choose your prefered direction.
After that you could just type Step from the keyboard and get exactly one Step of motor rotation.
If that is too small to see, you could just type
Step Step Step Step Step Step Step Step Step Step (return) to get 10 Steps and 18 degrees of rotation.
Next you may want to figure out how to create a word that with accept a number and do that many steps, say Steps.
So you could type
10 Steps to get 18 degrees
66 Steps to get near 120 degrees
Try changing direction and try disables. This will verify that the hardware set up is right and working with the software. And THAT is why I personally prefer Forth. It is extremely easy to use to verify you are doing things right or wrong.
~~~~~~~~~~~~~~
Then the Input......
Once you got all that working well, be can deal with the Cherry Proximity Sensor and how to create words for Input. Testing an Input requires a bit more knowledge as you will have to have a loop looking for a change in the state of the input from a High to a Low.
First just have it report a Hi or Low
Then create an endless loop with a bit of delay, say 50 milla-seconds.
Create a name for the loop and when activate the name, you can fool with a magnet and see changes from High to Low and back again.
Good suggestions on the bench test setup. I plan on working on that later today.
If you dislike PropForth, there is also TachyonForth.
What I am saying is the Propeller has lots of programing alternatives and I don't really want to burden you with what I prefer. It is more about what you want to learn and do.
Nonetheless, using PropForth V5.0 might just make this come together very quickly if you feel comfortable with it.
Above all, you don't NOT have to become an advanced Forth user. All you are using is ONE Cog.
http://bernd-paysan.de/gforth.html
PropForth and TachyonForth don't have many of the words of an ANSI standard Forth and while it is not really important to using a micro-controller such as the Propeller.. it caused a huge debate on these forums.
PropForth and TachyonForth DO have a lot of special features just for the Propeller 1. And maybe for the Propeller 2 soon.
So learning with GForth at first might be more comfortable for you. If you want to get started at the same time with Prop Forth, just learn to turn on and off or the LEDs on the QuickStart from your computer keyboard. That will give you an idea of its power. If you were to connect a relay to the same output as the LEDs, you could turn on and off anything that the relay is connected too.. like your 120VAC lighting in your home, or your TV or whatever.