a bit of trouble with the prop plug...
kutalinelucas
Posts: 80
After getting some fantastic advice that was well above my head! I decided to buy a prop-plug a few days ago, but I'm having difficulties already!
When I try to run 'identify hardware' or try to compile one of the included spin files, the blue led on the back of the plug flashes briefly, and I get a 'no propeller chip found on any com port' messagebox. The port is set to automatic in the preferences section of 'propeller tool', and when I connect the rx & tx pins of the prop, typed characters are ecohed through the parallax serial terminal, so I guess the drivers are installed correctly.
I've set it up on a brand-new breadboard, and I am supplying it with a wall-supply 11v through a 9v regulator, before using a voltage divider to get approximatly 3.25 v on the pins of the prop. This did worry me a little but i'm pretty sure the manual says it could still be run at 2.80v...
I'm running 64-bit windows 7, and I've included the circuit i'm using and a picture of the breadboard. Anyhelp to get me started would be brilliant
Thanks
When I try to run 'identify hardware' or try to compile one of the included spin files, the blue led on the back of the plug flashes briefly, and I get a 'no propeller chip found on any com port' messagebox. The port is set to automatic in the preferences section of 'propeller tool', and when I connect the rx & tx pins of the prop, typed characters are ecohed through the parallax serial terminal, so I guess the drivers are installed correctly.
I've set it up on a brand-new breadboard, and I am supplying it with a wall-supply 11v through a 9v regulator, before using a voltage divider to get approximatly 3.25 v on the pins of the prop. This did worry me a little but i'm pretty sure the manual says it could still be run at 2.80v...
I'm running 64-bit windows 7, and I've included the circuit i'm using and a picture of the breadboard. Anyhelp to get me started would be brilliant
Thanks
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Comments
I don't know if it is the source of your problem or not but it would be a good idea to use a couple of caps on the breadboard. Put a 0.1uF close to each Vdd pin on the Prop.
Have you measured the voltage at all the connected pins to make use they are really connected to power or ground?
Do you get a small voltage increase at P31 when you attempt to communicate with the Prop?
Duane
Yes the TX is connected to p31, but no voltage increase when I try to communicate, it just stays at a steady 3.35v, as does p30
All of the connected pins are fine, just at a bit of a loss now
You should also be able to detect the reset with a multimeter (I think).
On ProtoBoard picture I see links on 3.3V voltage rails from on group to another -- BUT I don't see that links on GND rails.
Maybe that is Yours problem.
and Hi duane but you are right, there is a voltage drop of between .02v - .08v on pin 31 when I click identify...what does this mean?
All it really means it the signal is making it to the pin.
You ought to also check the reset pin for a change when press F10. The Prop needs to be reset at right time to accept the program. Pin30 should also change as it answers back.
Is there anything else you can use as a power supply? I'd certainly prefer to see a good 3.3V regulator with the appropriate filter caps on the input and output. Also some .1uf caps between the power and ground leads right at the Propeller chip. If you have to use the setup you have then at least get some filter caps on it. I'm not a fan of that style PS and if you go that route then perhaps use a Zener to help regulate the voltage output. Getting a proper voltage regulator or real 3.3V supply would be best however.
Robert
All of the connections are fine...so it must be something else
Using a voltage divider to supply a circuit normally isn't a good idea. Not unless the current load is constant. You have the Prop, PropPlug and a LED which is going to vary the current draw. It would be highly desirable to use a 3.3v regulator. Then some problems on your breadboard might be eliminated. And YES to bypassing the Power pins on the Prop. My 2¢.
I do understand it's a flakey way of powering my circuit, but with only a prop chip and plug I wouldn't have thought regulating the current would be a problem, I didn't think it has been drawing enough for it to be an issue. I've reciently been running a pic18f using a similar set-up...again I know its not great but it seemed to be ok for the breadboard stages
Have You added decoupling capacitors to Ypu Propeller - as near Both sides of Voltage rails as possible.
And one 10uF on Crystal side for Power stability?
Just out of intrest...is the prop chip that tempremental? its just the voltage supply remains relativly stable (+/- 0.02v), the circuit is not drawing any current and other ic's I have worked with will accept a voltage change of 1 or 2v at Vdd without any noticible change in preformance
I have never run Propeller Tool's on Win 7-64 so I don't know how it works with Drivers --->
BUT in time You push F10 to Identify Propeller -- Have Led's on PropPlug blinking?
Yea, but how are you measuring this? The voltage could be doing all sorts of crazy stuff without being detected by most multimeters. I think you'd need an oscilloscope to be sure the power was staying clean. The small decoupling caps are good for this.
I've told Sapieha he should include his caution about decoupling caps in his signature to keep from having to keep typing it.
Sapieha gave me a good explanation about decoupling caps here.
The Propeller doesn't need to have a crystal or EEPROM hooked up to be able to have the computer identify or program it. Windows 7 x64 shouldn't be a problem either - thats what I run here in the office, and I program the Propeller all day long. As indicated in the reference schematic, the three signals you need to make sure are connected properly are the reset line, and the TX and RX lines. You should also make sure that the Vss (ground) lines are tied together - both on your power supply circuit and to the Prop Plug.
Also, for good measure if you have a voltmeter, check the voltage that your power supply circuit is sending to the Propeller. Just make sure that its around 3.0 ~ 3.3 volts. 2.8 V should be just fine too, but its good to have stable power.
Would you be able to upload a better image of the breadboard circuit? It would be helpful to see exactly how you have the Prop Plug connected to the Propeller.
Thanks!
I don't profess to have much skill in the way of circuit theory, but as the data-sheet says the operating voltage of the propeller is between 2.7v - 3.6v..., it draws hardly current, and the supply voltage IS regulated (before the voltage divider), I'm just concerned that its something else.
Believe me I know its a bodge of a power supply but i'm only in the breadboard stages and using what I have until the caverlry (the postman) turn up.
At the moment all i'm looking for is a ping! just a return instruction to let the 'virtual serial port' know there's acatually somthing on the end of it! The prog plug must be ok because When I send data through the Tx line, it is instantly returned through the Rx.
I know multimeters aren't exactly precise, but I wouldn't think the supply frequency would be relevant to simply identify the bloody thing. I'm just a little concerned that I will wait 3 days for a 3.3v regulator and it will not solve the problem
In that case Only thing I can give You --->
If You have another BreadBoard - Rebuild this circuity on it -- Some cheap breadboards have very high internal capacitance -- That can be problem.
Else better to build entire circuity on 40 pin's socket. By soldering all wires to Sockets pins and inserting Propeller IC after that.
Have you tested the reset line?
I'm guessing this is your only Prop, right?
I've read the Prop is very sensitive to having current pass from one Vdd to the other or from one ground to the other.
Where do you live?
Maybe one of us Prop heads can send you a new one faster than a different source.
Hey wait a minute. You're new to the Prop right? I have a QuickStart board with your name on it. Send me a PM with your address and I'll mail a QuickStart board to you.
Duane
You wrote "...I wouldn't have thought regulating the current would be a problem," I hope you meant regulating the voltage. I wonder what the Prop current draw is with it in this circuit and with no program loaded. There should be some current but that should be fairly low as no program is running.
With a 1.3K resistor from the regulator, there wouldn't be very much current available @ 3.3v. The resistive divider output would drop as any current draw increases. Not a very 'stiff' voltage source for the Prop. Without the Prop, there is about 4.6 ma through the 600˙Ω resistor. If the Prop drew 1 mil out of the R-divider, the output would drop about 1.3v, closer to 2v.
Here's a few more pictures of the breadoard...all the connections are fine and show a regulativly stable 3.28v, I have live on the reset and p31when the usb is connected and a common earth for vss, the supply and after the regulator
please tell me its something simple!
As I see it --- You not have standard Capacitors to Voltage regulator -- Not any to Propeller to.
That circuity will never RUN. As I said You need caps 100nF on both sides of propeller and one 10 to 33uF on Crystal side (PLL side of propeller) --- BUT to that You need even 100nF on both sides of V-Regulator InVoltage and OutVoltage --- and parallel with them Electrolytic else Tantalum 10 to 47uF on both sides of V-Regulator to have Stable Voltage to Propeller.
Else forget You can RUN it!
Well as I said my circuit theory isn't up to much but thats a pretty good explation...i've ordered the regulators anyway but im just worried something else will go wrong
Edit: P31 should connect to PPlug's TX (next to /RES).
10uF to 33uF electrolytic/Tantalum capacitor -- On same side Propeller have pins to Crystal.
.but do I also need a 100nf cap each side of the regulator?
That is very important. And as I write in previous post even parallel with them Tantalum/electrolytic ones 10uF to 47uF TO!
let's estimate your propeller draws just 1 mA.
at 3.3V this means a inner resistance of 3.3V/0.001A = 3300 Ohm.
This resistance is in parallel to your 600 Ohm.
The resulting resitance is 1/(1/3300 + 1/600) = 507 Ohm.
Now the voltage gets divided down to 9V/(1360 Ohm + 507 Ohm) * 507 Ohm = 2.4V which is definitly too low.
You could try to use another resistor but as soon as the current that the propeller-chip is drawing changes the voltages will change too
If you only add a single LED drawing 20 mA the new inner resistance is
3.3V / 0.021A = 157 Ohm
1/(1/157 ohm + 1/ 600 ohm) = 124 Ohm
New Voltage: 9V / (1360+124) * 124 = 0.75V !!!
This is the reason why voltage-regulators are manufactered!
As long as your knowledge about electronics is low you should follow the advice of the manual and experts exactly
keep the questions coming
best regards
Stefan
As far as I can tell from the new photos, your wiring looks correct. Perhaps it is a port issue, check all your settings, and try reinstalling the USB driver.
Bruce
EDIT: With exception of the power source