Please Help with PWM Pal Connections
clloyd
Posts: 31
The datasheet somewhat confuses me stating that it is supposed to connect directly underneath a 24 pin module. I dont think I am able to do that so I understand that I have P12-15 as the motor outputs and P0 as the serial IO. Where is the Vcc, ground, or any other possible "needed" connections.
Post Edited (clloyd) : 11/9/2008 2:52:18 AM GMT
Post Edited (clloyd) : 11/9/2008 2:52:18 AM GMT
Comments
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· -- Carl, nn5i
In the attached PWMPAL photo, the dot referred to is the white one visible right next to the "P" of "Parallax". The pin next to it is pin 1. Assuming that your PWMPAL looks like that one, you should have no trouble identifying pin 1.
As for your other question, why are you unable to mount it beneath a module? If it's because you're using a surface mounted BS2, you should probably be using a SERVO PAL instead.
The PWM Pal we have says REV B rather than REV A, not sure if that makes a difference as far as what it does or not. It also does not have the white dot but I am going to assume that the white dot would be to the left of where the parallax is written. And no we are using the stamp evaluation board B2sE not the 24 pin module so it doesnt seem as if we can mount it underneath of it as it states in the datasheet. As far as the pins go:
If Pin 1 is that upper left pin the where would be P0 the one that is stated in the datasheet:
Pin PWMPAL Function Dedicated
P0 Serial link between BASIC Stamp / PWMPAL Yes
P8 Counter 1 input / Motor 1 HW control No
P9 Counter 2 input / Motor 2 HW control No
P10 Counter 3 input / Motor 3 HW control No
P11 Counter 4 input / Motor 4 HW control No
P12 Motor 1 output No
P13 Motor 2 output No
P14 Motor 3 output No
P15 Motor 4 output No
Does P0 refer to Pin 1? And thus P12 would be the pin on the bottom right of the PWM pal chip? Also still wondering where I would connect the Vdd and the ground. Not sure how much I can define my problem, just need to know the pin connections on the chip.....
www.parallax.com/Portals/0/Downloads/docs/prod/schem/BS2revJSchematic.pdf
For example, you'll notice that I/0 pin 0 is physical pin 5, the fifth from the top on the left side of the module (and therefore also on the PWM Pal module, as it plugs into the BS2 in a one-to-one way). The power and reset pins are 21-24, over on the top right side:
21 - Vdd
22 - Reset
23 - Vss
24 - Vin
Pin 4 is also a Vss pin (ground).
I think that you're safe in assuming that the pin next to the "P" of "Parallax" on your unit is physical pin 1 of that unit, even if there is no little white dot.
However, I don't know if you're safe in assuming that you can just plug separate wires from your BS2 module into those little holes on the PWM Pal. You might want an expert opinion on that (read: someone from Parallax).
Post Edited (sylvie369) : 11/8/2008 9:55:43 PM GMT
Thanks a lot!
Hardware:
We connected P4 and P23 to ground. Connected P24 and P21 to +5V. Connected P22 and P5 to the microcontroller (For the input and the reset). We connected P17 to a motor then tested with LED and multimeter and it was not outputting anything.
Software:
SEROUT PWMPal, PWMBaud, [noparse][[/noparse]"!PWMM1", 50, 0, $EE, $02] '50 Hz adds up to 800;
SEROUT PWMPAL, PWMBaud, [noparse][[/noparse]"!PWMSS", %00010000] ' enable PWM outputs
Tested these commands in both orders, no results.
Any suggestions?
Do you know the Stamp is actually functional?· That is, does it work in, say, a BOE or a Homework Board?
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· -- Carl, nn5i
If you are referencing if the microcontroller (we are using a homework eval board)·is functional, then yes it definitely is.· But should everything else work?
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Chris Savage
Parallax Engineering
We dont have the 24 pin stamp module.
Can we use the PWM pal with homework board and if so what is connected to where.
There is an example code to blink an LED on the data sheet of the PWM pal, I think that would be a good start off for us. But all the connections we
have tried did not seem to work with the Home work board and PWM pal
So if you would help us what to connect where and make it work. (or just to say "what would you do if you have PWM pal and a Homework board )
thanks
clloyd's Friend
Post Edited (clloyd) : 11/10/2008 9:37:24 PM GMT
Post Edit -- I don't know if a connection to Reset is necessary.· I don't see a trace connected to it in the pic·attached by·Sylvie.· Haven't located a schematic.·
The labels on the Dwg. refer to the labels on the HWB headers.
Previously you posted "Connected P24 and P21 to +5V."· Not good. ·Vin is from the battery and Vcc is 5V (they are different.)· Looks like only Vcc is used.
Post Edited (PJ Allen) : 11/10/2008 10:42:42 PM GMT
The connection diagram you have given me actually, we have tried it.
but it never worked,
My question is, is it even possible for the PWM pal to work with HW board? at all?
If not, can we buy the 24 pin module and connect it to the PWM pal and still be able to control it using the HW board?
We are doing a project. we already setup all other components such as (GPS, digital Compass) to work with the H.W board and every things is working right.
But now we want to add motors which will be operating based on GPS and digital compass reading.
As you know the motors need some kind of PWM, so that was why we needed the PWM pal but that just does not seem be able to work with the HW board.
If you have any suggestions ?
If you connected PWMPAL pin 21 to "Vin", as a previous post indicates, then it may have snuffed it.
Post Edit -- it's the "smoking" thing, man, not good
Post Edited (PJ Allen) : 11/10/2008 11:19:28 PM GMT
but
What
Chris Savage
Parallax Engineering
said is that you can connect it to the 24 pin module and the pins "The pins these signals go to corresponds to the same pins the PWM Pal would connect to on a module if you had it." but he did not mention any thing about the HW board and as you know the HW board has only 15 I/O so how do we go about that?
But
before we buy another one I just wanted to make sure 100 % this things works, with the HW board or some one to tell us what other components we may need to control the PWM pal from homework board.
Thank you
Not so.· The HWB has 16 I/O lines, P0-P15; P0, 8, 9, 10, 11 are used by the PWMPAL.
As I see it, if a PWMPAL was connected in accordance with the diagram I attached then all should be well.
Before buying anything further, you should seek guidance from Parallax Tech Support.
and obviously all the GPS and digital compass as well may be a servo motor takes up a couple of pins on the HW board.
So we can't connect the PWM pal as if it is connected to a 24 pin module (of course that's impossible because we only have 16 pins). But on the diagram you sent me I have modified some things and take a look at it, and let me know what you think ?
Post Edited (clloyd) : 11/10/2008 11:57:31 PM GMT
I guess you could connect PWMPAL pin 5 to HWB's P9 --·but make sure that you comm using SERIN 9, SEROUT 9 (not SERIN 0, SEROUT 0.)
Post Edit -- In this context, I don't know what "IED" is that you have·on pins 19, 20.
But what we were trying to do there is that at least to begin with blinking an LED that was shown and on the data sheet
http://www.parallax.com/Portals/0/Downloads/docs/prod/acc/PWMPAL.pdf page 13 and the code is there as well
And of course on the program we begin with
' =========================================================================
'
[noparse][[/noparse] I/O Definitions ]
PpPin PIN 9 ' PWMPAL Serial I/O
.
.
.
'=========================================
I'd look at the output/s (MOT1 - MOT4, PWMPAL pins 17-20) with an oscilloscope.· Sorry, but, the smoking doesn't bode well.
and the LED is a bi-color LED.
I mean some one has tried this before? Is there any one who has access to these two components and be able to prove that we can generate a signal.
(connecting PWM Pal with HW board? and getting a signal?)
If so I don't mind buying other PWM pal but we need to do it ASAP. because if some one recommended another component as well, it would be good to buy all the things needed and put them in one shipping order.
The PWMPAL is a 24-pin smart socket. If you’re going to plug it into the breadboard on the H/W Board then you need to provide the connections it would normally require if it was connected to a standard 24-pin module. Let’s start with the basics…you must have a common ground.
Pin 23 on the PWMPAL is VSS. This should go to VSS on the H/W Board.
Pin 22 on the PWMPAL is /RESET, but this is optional so we won’t connect it.
Pin 21 on the PWMPAL is VDD. This should go to VDD on the H/W Board.
Now for signals…
Pin 5 on the PWMPAL is the serial I/O line. For compatibility with existing code this should connect to P0 on the H/W Board, although any I/O line could be used if the code reflects this. These are the only connections required. The PWM outputs can be picked directly from the PWMPAL itself (using common ground).
I hope this helps. Take care.
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Chris Savage
Parallax Engineering
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Chris Savage
Parallax Engineering
We are doing a group project. So we were trying to get help as much as possible in our own way.
Such as one person discussing in the forum, the other may be emailing Parallax, or calling and getting suggestions.
Thank you I just got the picture
Post Edited (clloyd) : 11/11/2008 7:02:03 PM GMT
Is your project working with the information above? As you can see I connected a scope probe to be sure the PWMPAL was doing what it should be, but you can also just run the version ID code.
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Chris Savage
Parallax Engineering
That tip helped (pulling high the reset)
It is working fine now. The Bi directional LED is going well
Thank you again for your great help and all the good people who contributed to this.
clloyd and friends