Electronics > Repair
[FIXED] Venerable AIM TTI PL303QMD-P needs help - Overvoltage trip error
m k:
Dang, I though it has only one MCU.
Well, then you just compare 8 ADC inputs to other 8 ADC inputs.
Very simple.
m k:
ADS1241 high nibble of opcode can be only 0, 1, 5 or F.
So 5 (1+4) bytes is fine, but 48 or 40 can't be any opcode.
3 times the same set indicates it's close.
And 1st byte is recognized as an opcode, or is it.
Answer could be one from negative limit of 24bit signed value, if MSB is right.
But then opcode must be 1.
4 8 4
0100 1000 0100 0000 0000 0000 0000 0000 0000 0000
MSB still right and shifting 2 bits would be xx 01.
But then 1st byte doesn't fit.
E,
obviously not -2.
E2,
boot has 8 frames of right CC LED, later left CC LED on is a bit shorter.
May that CC LED can be a trigger for checking the fault test moment.
Zucca:
Thanks m K! So cool
I will dig into it the next days... I hope there are no noise that are causing some bit flipping... I have also a Picoscope that for decoding SPI maybe it is better...
Crucial will be the startup phase... what I posted above was just a proof dirty try/proof of concept...
Tonight I compared the good and bad ADC inputs regarding the Vsense lines (the one causing the OVP)
Good one
PIN
16 Vsense- 2.402V
15 Vsense+ 2.402V
9 REF+ 2.510V
Bad one
PIN
16 Vsense- 2.402V
15 Vsense+ 2.402V
9 REF+ 2.511V
as expected the analog part works and matchs my Spice sim.
m k:
Was your measuring GND far away?
Maybe the chip has some problems with it.
If those boot LEDs are what they are marked to be it's like master side has equally bad voltage and current.
When booting two slave side LEDs come on together, but master side has a delay.
Delay can mean that boot is waiting that tested voltage is settling down, that never happens, and then does the same wait for current.
Zucca:
--- Quote from: m k on August 14, 2024, 04:27:50 pm ---ADS1241 high nibble of opcode can be only 0, 1, 5 or F.
--- End quote ---
m k is right!
I had a wrong MSB/LSB setting in the previous screenshots.
Let me dig a little bit further and I will report my findings soon!
Thanks again m k!
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