We are developing a BMS using MP2787 and ̶M̶P̶F̶4̶2̶7̶9̶7̶ MPF42791. We are able to communicate with MP2787 and obtain all the readings. However we are unable to establish communication with MPF42791. Are there any utilities we can use for debugging?
Would be great if anyone can share an example of a command and response received over I2C.
Anand Teke
Hello Anand,
Thanks for reaching out to the MPS Forum. I see you’re inquiring about I2C communication with the MPF42797.
There should be proper pull-ups to a DC voltage on the SCL and SDA lines. Are you able to do a scan of the I2C devices and see it respond? Can you share a schematic?
I would suggest probing the SCL and SDA lines to see if the voltage levels are not getting to the desired level for communication. Could you provide the SDA and SCL waveforms? A stronger pull-up resistor value may be needed.
Thanks Stephen.
The chip we are using is MPF42791
As suggested by you, we reduced pull ups on I2C lines from 10k to 2k. Even then chip is not detected on I2C scan.
Will try to get waveforms and aslo share schematic.
Hi Anand,
Apologies, there was a typo. Thanks for clarifying. If using the MPF42971, there are different operating modes that can dictate if the IC can communicate via I2C.
While you attempt to get schematics, can you confirm the mode it is operating in? Active, stand-by, or disabled?
The problem has been resolved after putting the chip in active mode as you suggested.
Thanks Stephen.