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Hot!MCLR capacitor (RC) required for PIC24FJ64GA705 ?

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cea
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Re: MCLR capacitor (RC) required for PIC24FJ64GA705 ? 2020/09/18 11:08:02 (permalink)
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NorthGuy
dan1138
I can open it using the Foxit Version:  8.3.0.14878 PDF reader without any password.

DS80000718F. I have FoxIt 5 (from before they turned into adware). Anyway, I could open it in Mac.
 
It is nothing in the errata that is relevant for the OP's situation. All oscillator errata are about the external oscillator and have nothing to do with FRC.

In my view the DS80000718F errata uniquely obfuscates anything useful in the description of issues with the oscillator function block. After reading it several times I cannot say with any certainty what may or may not apply to the Original Posters issues.
 
What I do know and can prove is that the oscillator function block as implemented in the PIC24FJ256GA705 revision A3 silicon has issues.
post edited by cea - 2020/09/18 11:09:29
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NorthGuy
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Re: MCLR capacitor (RC) required for PIC24FJ64GA705 ? 2020/09/18 12:34:48 (permalink)
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charles@socketcom
... DS80000718F ... After reading it several times I cannot say with any certainty what may or may not apply to the Original Posters issues.



But I can.
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dan1138
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Re: MCLR capacitor (RC) required for PIC24FJ64GA705 ? 2020/09/18 14:20:16 (permalink)
5 (1)
error, post to wrong thread
post edited by dan1138 - 2020/09/18 14:29:35
#83
dan1138
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Re: MCLR capacitor (RC) required for PIC24FJ64GA705 ? 2020/09/18 14:20:55 (permalink)
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error, post to wrong thread, and I did it twice. Sorry.
post edited by dan1138 - 2020/09/18 14:30:40
#84
cea
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Re: MCLR capacitor (RC) required for PIC24FJ64GA705 ? 2020/09/18 14:22:58 (permalink)
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NorthGuy
charles@socketcom
... DS80000718F ... After reading it several times I cannot say with any certainty what may or may not apply to the Original Posters issues.

But I can.

Are you able to post an objective example of code that can reproduce the OP's fault and show definitively that the fault is not described in the DS80000718F errata?
 
You could start with my code from post #41.
post edited by cea - 2020/09/18 14:27:04
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cea
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Re: MCLR capacitor (RC) required for PIC24FJ64GA705 ? 2020/09/18 14:23:17 (permalink)
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I am double posting now but I think I know how to avoid doing it again
post edited by cea - 2020/09/18 14:28:23
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NorthGuy
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Re: MCLR capacitor (RC) required for PIC24FJ64GA705 ? 2020/09/18 16:31:03 (permalink)
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charles@socketcom
Are you able to post an objective example of code that can reproduce the OP's fault and show definitively that the fault is not described in the DS80000718F errata?
 
You could start with my code from post #41.



Code? The OP's screenshots show that he only sees couple clock pulses. This is not enough even to execute the original "goto", let alone to run any code. Therefore, except for config bits, it's irrelevant what the code is. CPU cannot run without a clock, either correctly or incorrectly, commands cannot execute, traps cannot occur.
 
In your case, you didn't have that. The oscillator was starting fine every time, you could run the code and then very specific code was causing the problem.
 
In OP's case, since the same PIC runs well when controlled by the programmer, it is more likely that something is wrong with the board than with the PIC - power, reset, these sorts of things.
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cea
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Re: MCLR capacitor (RC) required for PIC24FJ64GA705 ? 2020/09/18 18:20:16 (permalink)
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NorthGuy
charles@socketcom
Are you able to post an objective example of code that can reproduce the OP's fault and show definitively that the fault is not described in the DS80000718F errata?

You could start with my code from post #41.

Code? The OP's screen shots show that he only sees couple clock pulses. This is not enough even to execute the original "goto", let alone to run any code. Therefore, except for config bits, it's irrelevant what the code is. CPU cannot run without a clock, either correctly or incorrectly, commands cannot execute, traps cannot occur.

In your case, you didn't have that. The oscillator was starting fine every time, you could run the code and then very specific code was causing the problem.

In OP's case, since the same PIC runs well when controlled by the programmer, it is more likely that something is wrong with the board than with the PIC - power, reset, these sorts of things.

I think you have a valid point in that the OP's code fails somehow within the first one or two instruction clocks.

The PIC24FJ256GA705 family uses ECC checking on the flash memory.

When I was debugging boot loaders for PIC24F with ECC flash I provoked a lot of very strange behaviors when ECC faults could not be handled correctly. In some cases the controller was so locked up I had to bit-banging a command into the PGD/PGC with an FTDI chip to force a chip erase.

So here's a scenario that covers what I think the OP's has observed:
  1. The controller can be erase and verifies as blank with the ICD tool.
  2. The controller can be programmed and verified by the ICD tool.
  3. When the user application executes with an ECC fault detected at address 0x0000 and at the IVT entry of the ECC trap handler. The result is a double fault without any code executing.
This would require a fault in the ECC silicon implementation. This does see a bit far fetched, but do you have anything else?

<EDIT>
The OP has also observed that the faults follow the chips not the boards. This would suggest that the PCB design and assembly are good enough.
post edited by charles@socketcom - 2020/09/18 18:45:19
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NorthGuy
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Re: MCLR capacitor (RC) required for PIC24FJ64GA705 ? 2020/09/19 20:33:17 (permalink)
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charles@socketcom
The OP has also observed that the faults follow the chips not the boards. This would suggest that the PCB design and assembly are good enough.



The OP had 70% yeild, so most of the PICs work, but some don't, most likely because everything is mostly Ok, but not quite. The board satisfies the majority of the PICs, but not all. Whether the board is faulty, or the PICs batch is not quite to the specs, the important thing is that this can be improved because the problem goes away when the bad PIC is controlled by the programmer.
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cea
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Re: MCLR capacitor (RC) required for PIC24FJ64GA705 ? 2020/09/19 21:06:16 (permalink)
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NorthGuy
... the important thing is that this can be improved because the problem goes away when the bad PIC is controlled by the programmer.

I know that user2x commented on this in post #62 but then I must be hard of thinking because that post does not seem clear enough for me to understand all of it.
 
Think about what the ICD tool does when the IDE uses it to connect to the controller:
It puts the controller in programming mode to read the chip's device ID.
Then it resets the controller and lets the application start.
 
When the IDE is asked to hold the controller in reset this seem to happen about twice before the MCLR line is held low.
 
I have observed that this reset from the IDE appears to operate like a Power-On-Reset, not an MCLR reset. I do not see how this can have any impact on the OP's issues.
 
It would help to have one of the controllers that the OP knows has failed to see if I can reproduce the fault in my circuit.
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user2x
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Re: MCLR capacitor (RC) required for PIC24FJ64GA705 ? 2020/09/20 15:16:25 (permalink)
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Hello, OP here...
 
For those that keep mentioning about possible design issues and the pcb/soldering etc, please keep in mind that the PIC only needs power , MCLR and Vcap to operate.
It is really basic and not rocket science to ensure that this is provided and correct. 
I can also add that the design has been verified by the chip manufacturer since and there were no issues found except that there is no capacitor on MCLR.
 
I also had a meeting with the chip manufacturer and one possible avenue they will follow up on is that it might be a temperature variation on something to do with the oscillator. This is because it will work when the chip is heated.
 
They also sent me test code they wanted me to run.
It works fine, until I change the config line from FRC to OSCDIV (which is what I have).
 
After a whole weekend, I now still have 6 out of 6 boards operating, with the Config set to FRC.
 
I am feeling moderately optimistic.
 
 
 
 
 
post edited by user2x - 2020/09/20 17:55:02
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NorthGuy
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Re: MCLR capacitor (RC) required for PIC24FJ64GA705 ? 2020/09/20 17:39:53 (permalink)
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user2x
After a whole weekend, I now still have 6 out of 6 boards operating, with the Config set to FRM.

 
FRC you mean? That's what I suggested in post #40. Back then you said it didn't work.
 
#92
user2x
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Re: MCLR capacitor (RC) required for PIC24FJ64GA705 ? 2020/09/20 17:59:50 (permalink)
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NorthGuy
 ...Back then you said it didn't work.
 



Are you sure I said that? 
 
I had to work my way through a lot and I have also been testing that option since I have the chips back on new boards from rework.
 
 
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NorthGuy
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Re: MCLR capacitor (RC) required for PIC24FJ64GA705 ? 2020/09/20 18:20:37 (permalink)
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user2x
NorthGuy
 ...Back then you said it didn't work.


Are you sure I said that? 

 
No, I'm not sure. But in post #42 you said:
 
user2x
I actually have 3 boards now set to FNOSC = FRC.
I am testing these today.

 
So, apparently you have already tried this 5 days ago. I cannot know the results, of course.
 
If FRC works then this is, indeed, the divider problem that half of the thread was about.
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user2x
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Re: MCLR capacitor (RC) required for PIC24FJ64GA705 ? 2020/09/20 18:33:23 (permalink)
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YEs, I have been trying this some days ago but also other stuff so the outcome was not known on more than a 1 off sample.
 
I know as of this morning that 6 CPU chips that all have this problem, seem to be cured - as far as I can tell - with changing the setting to FRC.
 
I agree, it is either the fractional divider or the FRC itself that maybe cannot handle the load that the divider plus PLL place on it on some chips.  Or something else altogether. 
It has to be something that varies a bit between chips.
 
I do not know.
 
 
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cea
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Re: MCLR capacitor (RC) required for PIC24FJ64GA705 ? 2020/09/20 18:49:28 (permalink)
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user2x
Hello, OP here...
 
For those that keep mentioning about possible design issues and the pcb/soldering etc, please keep in mind that the PIC only needs power, MCLR and Vcap to operate.
 
It is really basic and not rocket science to ensure that this is provided and correct.
 
I can also add that the design has been verified by the chip manufacturer since and there were no issues found except that there is no capacitor on MCLR.
 
I also had a meeting with the chip manufacturer and one possible avenue they will follow up on is that it might be a temperature variation on something to do with the oscillator. This is because it will work when the chip is heated.
 
They also sent me test code they wanted me to run.
 
It works fine, until I change the config line from FRC to OSCDIV (which is what I have).
 
After a whole weekend, I now still have 6 out of 6 boards operating, with the Config set to FRC.
 
I am feeling moderately optimistic.

@user2x,
 
Do you have a support case number with Microchip?
 
This is of concern to me because we have a product using the same controller going into production in a few weeks.
 
If there is any insight that Microchip informs you about please share it here.
 
And yes my code does not use the fractional divider with the system oscillator, I got screwed another way.
post edited by cea - 2020/09/20 18:50:41
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user2x
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Re: MCLR capacitor (RC) required for PIC24FJ64GA705 ? 2020/09/20 18:53:23 (permalink)
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Hi cea
Case #00554683
 
Can I PM you somehow?
 
Regards
X
 
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cea
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Re: MCLR capacitor (RC) required for PIC24FJ64GA705 ? 2020/09/20 19:05:00 (permalink)
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user2x
Hi cea
Can I PM you somehow?

Yes, my PM is on now.
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user2x
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Re: MCLR capacitor (RC) required for PIC24FJ64GA705 ? 2020/09/20 20:13:27 (permalink)
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charles@socketcom
 
Yes, my PM is on now.



You have mail.
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user2x
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Re: MCLR capacitor (RC) required for PIC24FJ64GA705 ? 2020/10/01 18:46:59 (permalink)
4 (1)
Update:
 
Latest advise is that Microchip will change the Errata 20 to include my encountered problem with the OSCFDIV.
Apparently they are confident (!) that the Vcap pre-charge problem (now) also applies to the divider.
 
Far out!
 
Cheers
X
 
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