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jimbotron
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Joined: 27/11/2013
Location: Australia
Posts: 50

Posted: 11:29pm 08 Jan 2014

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Hi Grogster. Have you tried another keyboard. Your symptoms sound similar to a problem I was having. I was getting mysterious lockups on a keyboard on a Raspberry Pi, but another keyboard was fine.
Turned out that the voltage supply was low and when the Pi was running a processor intensive task the voltage dipped even further hanging the keyboard.
It's worth noting that the keyboard runs of 5V, but the PIC32 uses the 3V3 rail. If the voltage dips you'll lose the 5V rail before the 3V3 rail. So it is quite possible to lose the 5V rail and still have a working PIC.

MicroBlocks

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Joined: 12/05/2012
Location: Thailand
Posts: 2209

Posted: 07:32am 09 Jan 2014

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Jimbo might be on the right track.
When you power it from the USB often you get only 4.5v out of the USB. It then has to go through a diode dropping another possible 0.6v ending up with 3.9v in worst case.

When power is from a 9v source it still goes through a diode after the regulator giving about 4.5v.

Maybe checking the voltage at the Ps/2 plug can rule that out.

Microblocks. Build with logic.

Grogster

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Joined: 31/12/2012
Location: New Zealand
Posts: 9486

Posted: 11:15am 09 Jan 2014

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Thanks guys, for the hints.

Prior to this thread, I have tried three or four different KB units, to rule out perhaps a faulty KB.

I have never run the MM from the USB power. I have always used a regulated plugpack. For the Dontronics B/W unit, I used a 9v regulated plugpack, and for the CMM2 from CG, I am using a 12v 400mA regulated plugpack. However, it was a very good idea, and you'd probably be on to something well worth trying out, if I indeed was using USB power.

Being regulated, and with 400mA reserve current, that should be tons for the PIC32 demands, and any KB you care to mention.

And before you ask, I have also tried plain old linear PSU's as well as these newer switchmode regulated plugpacks that are all the rage now. Things did seems to settle down on the linear PSU for a while, but just when I thought that must be the cause, I got lockups again on the linear supply, so it is not a PSU issue either.

I love a good mystery, but only if you can solve it at the end!

Voltage on the CMM2 KB header is 4.98v steady, with or without the KB plugged in.
When holding down a key(any key you like), voltage drops 0.01v to 4.97v - WELL within spec for the 5v KB voltage, I would think...Edited by Grogster 2014-01-10

Smoke makes things work. When the smoke gets out, it stops!

Grogster

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Joined: 31/12/2012
Location: New Zealand
Posts: 9486

Posted: 04:32pm 09 Jan 2014

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UPDATE: Just had another lockup. This was one where ENTER would work, but no other key works.

Further to my CTRL-C thing, and at the suggestion of CG, this time, I just pressed CTRL by itself a couple of times, then tried some keys, and away it went good as gold.

I will keep the thread updated with anything else that happens.

Smoke makes things work. When the smoke gets out, it stops!

Grogster

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Joined: 31/12/2012
Location: New Zealand
Posts: 9486

Posted: 11:51pm 21 Jul 2014

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Just need to revive this thread, cos tonight this issue is driving me nuts.

It is MUCH worse then it used to be - about 10 seconds is all I get before the keyboard does not work anymore, and all I get is the wrong characters, or nothing at all.

Cycle power - it's fine again, but only for about another 10-20 seconds then it always fails, and this is totally useless. To say nothing of the fact that I have watchdog commands all over the place, so the PIC32 is forever rebooting itself, cos you CAN'T get the command prompt to work to be able to disable it with a WATCHDOG OFF command...

This is the CG CMM2 unit. It was the CG CMM1 unit last time. I am wondering - is it even slightly conceivable that the PIC32 does not like the Switch-mode PSU chip that CG used in the design? Have any of the rest of you with CG CMM's ever had any KB lockup problems?

As this is a totally different board to the first one that had this issue, I am now pretty stumped as to what the hell could be causing this, cos we have ruled out PSU's and several different keyboard units too - nothing is stopping this from happening, and tonight was the last straw - just about drop-kicked the entire project THROUGH the window....

I will dig out my Altronics kits, as they use a standard linear regulator(as did Don's design for the B/W MM, and Geoff's own design), so about the only thing I can think of, is that the PIC32 does not like the taste of the SW-mode PSU - what the hell else is there? (rhetorical)

Smoke makes things work. When the smoke gets out, it stops!

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