Info: how I managed to read battery PIDs from my EV

[bobobo1618]

I have a Kia EV6 (same platform as the Hyundai Ioniq 5) and wanted to get the Freematics One+ Model B reading data from it. I've managed that and thought I'd share. I'd share on the forum but I'm waiting for a moderator to approve my posts for around a week now.

I prefer working with the ESP-IDF so I don't have code to contribute to the Freematics repo but here's what I did to get useful data out of my EV:

1. Figure out which ECU to talk to and which PIDs contain information I'm interested in. Folks have done a lot of work for the Hyundai Ioniq 5 so I just needed to look at this CSV. For battery information, I need to send PID 220101 to ECU 7E4.
2. Figure out which protocol the car uses. These guys say it uses ISO 15765-4, an 11-bit header and 500000 baud rate.
3. Use all this to talk to the OBD chip (I used the ELM327 manual for a lot of guidance):

// Reset the chip to start from a clean slate
ATZ
// Set the protocol to "ISO 15765-4 CAN (11 bit ID, 500 kbaud)" to match the car. The number "6" comes from page 27 of the ELM327 manual.
ATSP6
// Set up the CAN filter and mask to only allow responses from OBD-II ECUs. This follows the example on page 49 of the ELM327 manual.
ATCF7E8
ATCM7F8
// Tell the OBD chip to talk to the BMS, which has address 7E4 as discussed above
ATSH7E4
// We're now ready to start getting data
220101
// Data comes now...

Looking at the Freematics code, if you want to use the Freematics code to do the same thing, you need to:

• Hard-code a protocol to trigger the ATSP. For example in the telelogger example, you'd need to put PROTO_CAN_11B_500K here
• Call the setHeaderFilter and setHeaderMask functions (I suppose I'd add these calls around the OBD init code)
• Implement a fork of readPid that supports multi-byte PIDs and responses

[ankostis]

• Implement a fork of readPid that supports multi-byte PIDs and responses

Can you give an example request/response, in bytes?