AXP2101 not working properly CoreS3 with battery.
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We are using the M5 Stack with ESP-IDF. We have a CoreS3, Battery module and a CatM module.
After running in the field for a while. some device are not coming online anymore.
We tried resetting the device on location without success.
The only way to properly reset the functionality is to unmount the battery and remount is (Making sure no power is going to the M5Stack.)We can also not fix the device be rewriting firmware.
It turns out the power chip (Axp2101) isn't responding properly anymore. When we send command to it, it doesn't seem to work. (Sending 0x01 to 0x10 should power off the device, this doesn't happen).
It's not a I2C problem, we can succesfully contact the RTC and the IMU on the same bus.
We can write new firmware and flash it and the problem still occusrs, i can run some tests to get to the bottom of it.
We've compared registers in the AXP2101 from a good sample and a bad sample.
register good sample bad sample 0x00 0x38 0x30 0x01 0x32 0x4E 0x03 0x4A 0x0C 0x04 0x00 0x78 0x05 0x00 0x7E 0x06 0x00 0xED 0x07 0x00 0xF9 0x10 0x30 0x64 0x12 0x00 0x8D 0x13 0x03 0x73 0x14 0x65 0x7E 0x15 0x06 0x95 0x16 0x04 0xE3 0x17 0x00 0x0E 0x18 0x0A 0x70 0x19 0x06 0xF4 0x1A 0xA1 0x00 0x20 0x04 0x00 0x21 0x20 0x00 0x23 0x3F 0x00 0x24 0x00 0x00 0x25 0x18 0x00 0x26 0x08 0x00 0x27 0x00 0x00 0x28 0x00 0x00 0x29 0x00 0x00 0x2A 0x00 0x00 0x2B 0x00 0x00 0x30 0x0F 0x00 0x34 0x0C 0x00 0x35 0xD8 0x00 0x36 0x81 0x00 0x37 0xF8 0x00 0x38 0x13 0x00 0x39 0x62 0x00 0x3A 0x0E 0x00 0x3B 0x80 0x00 0x3C 0x00 0x00 0x3D 0x00 0x00 0x40 0xFF 0x00 0x41 0xFC 0x00 0x42 0x5F 0x00 0x48 0x50 0x00 0x49 0xA3 0x00 0x4A 0x28 0x00 0x50 0x1A 0x00 0x52 0x02 0x00 0x53 0x01 0x00 0x54 0x29 0x00 0x55 0x58 0x00 0x56 0x3E 0x00 0x57 0x4C 0x00 0x58 0x00 0x00 0x59 0x14 0x00 0x5A 0x37 0x00 0x5B 0x1E 0x00 0x61 0x05 0x00 0x62 0x08 0x00 0x63 0x15 0x00 0x64 0x03 0x00 0x65 0x02 0x00 0x67 0xE6 0x00 0x68 0x01 0x00 0x69 0x11 0x00 0x6A 0x03 0x00 0x80 0x05 0x00 0x81 0x00 0x00 0x82 0x12 0x00 0x83 0x46 0x00 0x84 0x69 0x00 0x85 0x64 0x00 0x86 0x00 0x00 0x90 0xBF 0x00 0x91 0x00 0x00 0x92 0x0D 0x00 0x93 0x1C 0x00 0x94 0x1C 0x00 0x95 0x1C 0x00 0x96 0x00 0x00 0x97 0x00 0x00 0x98 0x0E 0x00 0x99 0x18 0x00 0x9A 0x00 0x00 0xA1 0xFA 0x00 0xA2 0x00 0x00 0xA3 0x32 0x00 What could cause this behaviour?
How can it be resolved (using software preferably)
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Hello @RubberDuck
just curious, any particular reason you did not read out register 0x22? It is my understanding that this register determines whether the system powers off or does a reset when writing 0x01 to register 0x10.
Also curious, when the issue happens, is the battery full or close to be fully discharged?
The register values of the bad AXP2101 seem to be random. Have you tried to lower the I2C bus speed?
In my experience seemingly random issues often stem from bad / not sufficient power supply. Is the battery in good shape?
Thanks
Felix -
The data seems to be random indeed, however, it is always the same.
We did notice shark fin like signals on the i2c lines on 400k. We reduced it to 100k but the results stayed the same. We do not believe that the bad signal quality is causing the current issue we are having. On a good working board the signals look identical.For reference, here is inmage of the signal quality of the SCL/SDA line on 400k speed on the good board.:
The register values are taken with 100000 speed.
I think i forgot register 0x22. I've tested it and added it here:reg good sample bad sample 0x22 0x06 0x00 We've also tested writing the value 0 to 10 on register 0x04. On the good board we can read back the correct value. But on the bad board it always returns 0x78
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Hello @RubberDuck
I can confirm the shark fin like signals on my M5CoreS3. I am no I2C expert, but I think they might be marginal and so maybe just barely working on one M5CoreS3 but not on the other when talking to AXP2101. Maybe a stronger pull-up resistor might help?
BTW: I checked the I2C SCL line on an M5Core2 and it is much more rectangular, e.g. much more like I would expect it.
Thanks
Felix
