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View Full Version : Cannot Connect to Propeller - Reset Pin Damaged?



scdwyer
07-21-2009, 05:03 AM
Hello,

I have a Propeller Control Board RevA, and I can no longer·connect to it with the Propeller Tool v1.2.6. I am using a Prop Clip to try to connect. The board still seems to work with the currently loaded code (to control a Quadrover via RC control), but I cannot program it.

One thing I noticed with a voltmeter and oscilloscope was the RESn pin is not being pulled high like it should be - it is sitting at 0V. Would this indicate a damaged reset pin? Is it recoverable without replacing the chip? If not, I will attempt to remove the QFP package Propeller and replace it, though I would like to avoid this if possible.

If anyone has any thoughts, please share.

Thanks,
-Stephen

Nick Mueller
07-21-2009, 05:09 AM
> is not being pulled high like it should be - it is sitting at 0V. Would this indicate a damaged reset pin?

Au contraire, mon ami!
If it would be pulled high and the Prop wouldn't reset then you would be right.
Chances are, that the cabe is the cause or something in between the reset-pin and your connection.

Nick

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Never use force, just go for a bigger hammer!

The DIY Digital-Readout for mills, lathes etc.:
YADRO (http://www.yadro.de)

hover1
07-21-2009, 06:55 AM
Stephen,

Did you try another Prop Clip?

Or cable as Nick said, I have one or two go bad, (closing in car doors, etc.)


scdwyer said...
Hello,

I have a Propeller Control Board RevA, and I can no longer·connect to it with the Propeller Tool v1.2.6. I am using a Prop Clip to try to connect. The board still seems to work with the currently loaded code (to control a Quadrover via RC control), but I cannot program it.

One thing I noticed with a voltmeter and oscilloscope was the RESn pin is not being pulled high like it should be - it is sitting at 0V. Would this indicate a damaged reset pin? Is it recoverable without replacing the chip? If not, I will attempt to remove the QFP package Propeller and replace it, though I would like to avoid this if possible.

If anyone has any thoughts, please share.

Thanks,
-Stephen

jazzed
07-21-2009, 07:16 AM
Maybe your RES* line pull-up resistor is broken.

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--Steve


Propalyzer: Propeller PC Logic Analyzer (http://www.brouhaha.com/~sdenson/Propalyzer)
http://forums.parallax.com/showthread.php?p=788230 (http://forums.parallax.com/showthread.php?p=788230)

scdwyer
07-23-2009, 11:48 PM
@ hover1: I did not try another prop clip, but I do know the prop clip works as it is used regularly to connect to another Propeller control board and a protoboard, and it works great.

@ jazzed: The broken pullup is interesting. Based on that thought I tried·adding an external 10k pullup but unfortunately it did not help.

Any other thoughts? I think I will have to remove the propeller and replace it.

-Stephen

Rayman
07-24-2009, 12:03 AM
I think you do need Vdd on the RESn... If you have 0 V DC there, there's definitely a problem...

I've never heard of this as a mode of Prop failure, so I'd suspect the external circuitry....

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My Prop Info&Apps: ·http://www.rayslogic.com/propeller/propeller.htm

jazzed
07-24-2009, 01:00 AM
What is the power up state of the RESn pin without the PropClip connected ? Should be near 3.3V.
Have you tried checking RESn resistance to VSS/VDD? My PropProto board resistance is practically infinite to both.

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--Steve


Propalyzer: Propeller PC Logic Analyzer (http://www.brouhaha.com/~sdenson/Propalyzer)
http://forums.parallax.com/showthread.php?p=788230 (http://forums.parallax.com/showthread.php?p=788230)

scdwyer
07-24-2009, 01:38 AM
Hello,

I just checked the resistance, and between Vss and RES, there is only 5.1K resistance, while between Vdd and RES there is also only 5.1K resistance. This was measured in several places.

-Stephen

Bobb Fwed
07-24-2009, 01:44 AM
I had a similar problem just last week...the reset pin wasn't being driven low (kind of the opposite I guess)...I checked everything (connectivity of the pins, different devices, etc.) to get it to work. The RX and TX pins were definitely operating fine, but nothing on the reset. I finally just bought another prop plug (actually, two, just in case). The new one came in and it worked right away. Thus something on the old plug died.
I had the first prop plug for almost a year now...and it finally died, I will have a memorial service. You all are invited.

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April, 2008: when I discovered the answers to all my micro-computational-botherations!

jazzed
07-24-2009, 01:45 AM
Was that without the PropClip? Odd that resistance is so low. What is the resistance from VDD/VSS measuring with +/- normal and reverse?
How hard would it be to disconnect the propeller RESn pin? Is anything at all connected to the Propeller besides EEPROM and crystal ?

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--Steve


Propalyzer: Propeller PC Logic Analyzer (http://www.brouhaha.com/~sdenson/Propalyzer)
http://forums.parallax.com/showthread.php?p=788230 (http://forums.parallax.com/showthread.php?p=788230)

scdwyer
07-24-2009, 04:34 AM
The resistance was without the propclip or power. The Propeller is on·a Propeller Control Board, so there is a whole bunch of external circuitry attached permanently (mosfets, decade counter, servo ports with resistors etc), and it is also difficult to remove the RES pin with breaking it/a trace.

The prop clip is showing near infinite resistance between all pins when it is unpowered, and when the prop clip is attached to the board, the resistance between Vss and RES and Vdd and RES is still 5.1K each. This is the same regardless of which direction the test leads are attached. Note that this is when the prop clip is unpowered/not attached to a computer.

When the prop clip IS attached to both a USB port and the board, the resistances get weird, changing depending on test lead polarity etc.

Note the board is unpowered at all times.

I also tried using another programmer to no avail. It was a SparkFun Electronics FT232R Breakout board modified with a resistor-capacitor-transistor in the same fashion a prop clip/plug is setup.

Is there anything else I should check/measure?

jazzed
07-24-2009, 07:36 AM
Bob, I also have a dead PropPlug which worked wonderfully for over a year. It was killed by trying to provide power to a Propeller (and all the other connecting circuitry) through the serial port pins. I'm now convinced that an external supply should always be connect when the PropPlug is in use on boards that consume more than a few dozen milli-amps.

scdwyer, I'm afraid you have a problem that needs assistance from Parallax tech-support. They're good folks and should be able to help you one way or another.

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--Steve


Propalyzer: Propeller PC Logic Analyzer (http://www.brouhaha.com/~sdenson/Propalyzer)
http://forums.parallax.com/showthread.php?p=788230 (http://forums.parallax.com/showthread.php?p=788230)