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Need help with Frankenso 0.5 board, maybe short circuit or something is missing

Posted: Thu Jun 18, 2020 3:52 pm
by azasaw
Short background story, while playing with sensor inputs accidentally connected 5v pin to 12v source, blew my MAX9926/TPIC8101 and some pull up/pull down resistors. Now they have been replaced but I think i have more blown parts.
Question one: Can a stm ship be shorting too but still can connect to pc and communicate with tunerstudioand.

Question two: In attached picture there clt/iat sensors data but NO SENSOR CONNECTED, shouldn't raw volts be 5v?
Tempeture.PNG
Tempeture.PNG (82.94 KiB) Viewed 8861 times
And when I connect fake 300 ohm load it should be showing around 80C by NTC sensor data but it always stays stuck at around 40-50c.
CLT temp.PNG
CLT temp.PNG (58.04 KiB) Viewed 8861 times
Second time posing and now with pictures, I hope that everything is understandable.

Re: Need help with Frankenso 0.5 board, maybe short circuit or something is missing

Posted: Thu Jun 18, 2020 4:31 pm
by AndreyB
A1: any kind of partial damage is possible

A2: 4.5v is close enough to 5v. We do not know what exactly do you power with what and how exactly.

Re: Need help with Frankenso 0.5 board, maybe short circuit or something is missing

Posted: Thu Jun 18, 2020 5:00 pm
by azasaw
A2: ecu is powered by a bench power supply 12v and amp draw is around 0.09-0.10. It is connected to a 12v-switch pin and ground connected to a big pad labeled GND near the sd card slot.
Power.jpg
Power.jpg (4.02 MiB) Viewed 8857 times

Re: Need help with Frankenso 0.5 board, maybe short circuit or something is missing

Posted: Thu Jun 18, 2020 5:08 pm
by azasaw
And checking the 5v rail I have 4.99v, and voltage after pull up resistor is 4.98v or at pin that clt/iat connects i have 4.98v.

Re: Need help with Frankenso 0.5 board, maybe short circuit or something is missing

Posted: Thu Jun 18, 2020 5:25 pm
by AndreyB
So this is a real stm32 Frankenso without discovery? Very few people run those.

You need to investigate ADC reference voltage schematics and if it matches your "ADC vRef voltage" setting.

Re: Need help with Frankenso 0.5 board, maybe short circuit or something is missing

Posted: Thu Jun 18, 2020 6:45 pm
by kb1gtt
Can you check the op-amp circuits? Those could be broken, or the STM32 could be broken. Do you measure the proper volts on the STM32 pin, then read an incorrect value in TS? Currently My guess is that the op-map is not providing a proper signal to the STM32, so the STM32 then provides a bad signal to TS.

Re: Need help with Frankenso 0.5 board, maybe short circuit or something is missing

Posted: Thu Jun 18, 2020 7:24 pm
by azasaw
AndreyB: Yes Frankenso without discovery, you mean this?
Vref.PNG
Vref.PNG (398.07 KiB) Viewed 8840 times


kb1gtt: op amp with no sensors connected have an output of 4.91v on leg 8/9 and 13/14, and at stm32 pin I haves 2.45v

Re: Need help with Frankenso 0.5 board, maybe short circuit or something is missing

Posted: Thu Jun 18, 2020 7:32 pm
by AndreyB
Yes, what do you measure there and what does "ADC vRef voltage" setting say in Tuner Studio?

Re: Need help with Frankenso 0.5 board, maybe short circuit or something is missing

Posted: Thu Jun 18, 2020 7:46 pm
by azasaw
I have 3.27v on pins and in tuner studio i have 3.00.

Re: Need help with Frankenso 0.5 board, maybe short circuit or something is missing

Posted: Thu Jun 18, 2020 8:07 pm
by AndreyB
change 3.0 to 3.27v

it could be that discovery and Frankenso VDDA schematics is different

Re: Need help with Frankenso 0.5 board, maybe short circuit or something is missing

Posted: Thu Jun 18, 2020 8:21 pm
by azasaw
Yes changed it to 3.27 now the raw voltage dial shows around 5v, but I still have the same problem the temperature doesn't move past 50c and with nothing connected shows 8c, doesn't correspond to ohm calibration.

What voltage I should be getting at an stm32 leg with a disconnected sensor? I have 2.45v.

Re: Need help with Frankenso 0.5 board, maybe short circuit or something is missing

Posted: Thu Jun 18, 2020 8:39 pm
by AndreyB
op-amp divider ratio is 2:1 so 5v becomes 2.5v

Re: Need help with Frankenso 0.5 board, maybe short circuit or something is missing

Posted: Thu Jun 18, 2020 8:55 pm
by azasaw
For clarification purposes but dose, the op-amp has inside divider ratio or are two resistors like R214/R215 does that, because at op-amp output leg I have 4.91 but after those resistors, I have 2.45. and after those resistors track goes straight to the stm32 pin

Re: Need help with Frankenso 0.5 board, maybe short circuit or something is missing

Posted: Thu Jun 18, 2020 9:55 pm
by kb1gtt
Yes the op-amp has a divider. Yours appears to be a correct 2:1 step down. The ADC is limited to something like 3V, so we have to step down the 5V to below 3V.

Re: Need help with Frankenso 0.5 board, maybe short circuit or something is missing

Posted: Thu Jun 18, 2020 10:05 pm
by azasaw
So it seems that the stm32 chip being broken is the culprit of strange reading I'm getting in tuner studio.