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checking communication error between esp and STM
Posted: Fri Jun 13, 2025 12:52 pm
by DRSpeedster
Hello everyone,
I'm a student from UHasselt in Belgium and for my master thesis I'm converting an Opel Speedster With an internal combustion engine to an EV. I'm using an Tesla LDU and the logic board swap for this motor from the Openinverter store. After connecting the logic board and the esp I am unable to see the LDU data on my laptop. I keep getting the "Communication problem between ESP and STM" error and don't know what the problem is. The esp is updated and the wiring is tripple checked, the logic board ligthes up in the motor so it is getting power but wil not communicate with the esp.
Can there be a problem with the connector between the inverter and the 23 pin socket?
Re: checking communication error between esp and STM
Posted: Fri Jun 13, 2025 6:11 pm
by uhi22
Is the ESP connected via CAN or is it directly on the inverters logic board?
Re: checking communication error between esp and STM
Posted: Mon Jun 16, 2025 9:09 am
by DRSpeedster
It is connected via CAN.
Re: checking communication error between esp and STM
Posted: Mon Jun 16, 2025 5:40 pm
by uhi22
In this case the first check is the physical connection:
Resistance between CANH and CANL between 60 and 120ohms? Grounds connected? Do you have an oscilloscope to check the CAN lines? Baud rate correctly configured?
Re: checking communication error between esp and STM
Posted: Tue Jun 17, 2025 1:16 pm
by DRSpeedster
The resistance between CANL and CANH is 60 ohms, the grounds of the esp and the ground of the motor are connected. If I measure the voltage from the ground of the esp module and the CANL or CANH I get 2,3Vfor both. If I check the CAN lines with the oscilloscope I also get the same value of on bothe CANH and CANL (the value differs a smal amount of 0,1V max). For the baud rate I tried changing the Speed setting on the dash board from 125k to 250k and 500k with no results.
Re: checking communication error between esp and STM
Posted: Thu Jun 19, 2025 8:58 am
by DRSpeedster
Small update: When changing the speed from 250k to 500k, the error disappears and the interface works. However, when I start the interface at 500k, it does not work and the error remains. Is there a specific reason for this?
Re: checking communication error between esp and STM
Posted: Thu Jun 19, 2025 9:41 am
by Jacobsmess
What is the resistance between CAN H and CAN L? Is there anything else on the CAN circuit?
Re: checking communication error between esp and STM
Posted: Thu Jun 19, 2025 9:55 am
by DRSpeedster
The resistance between CANH and CANL is 60 ohms and at the moment it is only the logic board and the esp module on the CAN circuit
Re: checking communication error between esp and STM
Posted: Thu Jun 19, 2025 10:17 am
by johu
DRSpeedster wrote: ↑Thu Jun 19, 2025 8:58 am
Small update: When changing the speed from 250k to 500k, the error disappears and the interface works. However, when I start the interface at 500k, it does not work and the error remains. Is there a specific reason for this?
So it probably also works when changing Node Id to something else and back?