COMMUNICATION_ERROR

[PUW149]

I have an Rpi3B+ with a PiJuice HAT, nothing else on the GPIO. Everything was working fine and I was able to use the PiJuice software (GUI and CLI), but then started to get "COMMUNICATION_ERROR" in the PiJuice software. I have tried a couple of batteries in the PiJuice in case that was the problem. I2C is enabled and I get: pi@raspberrypi:/boot $ lsmod | grep i2c regmap_i2c 16384 1 rtc_ds1307 i2c_bcm2835 16384 1 i2c_dev 20480 2

and: pi@raspberrypi:/boot $ ls -l /dev/i2c-1 crw-rw---- 1 root i2c 89, 1 May 6 09:40 /dev/i2c-1

predictably given the GUI error, i2cdetect -y 1

gives nothing.

I am unable to flash the firmware (predictably as there is no I2C connection) ""error receiving data -1" when trying to update firmware"

If I check voltages with a multimeter

GPIO 2 gives 3.3V GPIO 3 gives 0.2V

both with PiJuice attached, and with it detached.

checking the GPIO pins gives:

pi@raspberrypi:/boot $ raspi-gpio get BANK0 (GPIO 0 to 27): GPIO 0: level=1 fsel=0 func=INPUT GPIO 1: level=1 fsel=0 func=INPUT GPIO 2: level=1 fsel=4 alt=0 func=SDA1 GPIO 3: level=0 fsel=4 alt=0 func=SCL1 ....

There is nothing unusual in config.txt

Questions: (i) Am I right in assuming that this means there is a problem with the RPi GPIO Bus? (ii) Can I set other Pins to be used as I2C rather than GPIO 2 and 3, and then get PiJuice to communicate using those pins? I am assuming that this is impossible as I can't communicate with the PiJuice to tell it to use alternate pins (iii) is it worth me trying a new SD card with a clean installation? or is this definitely the RPi hardware

Thanks, Simon

[tvoverbeek]

The I2C clock frequency varies with the Core frequency. Under load the core freq goes up and so does the I2C clock freq. I have seen this causing communication error. You can fix the core freq in /boot/config.txt. See the discussion in this issue: https://github.com/raspberrypi/linux/issues/4123 Suggest to first try with 'enable_uart=1' in /boot/config.txt

[PUW149]

Thanks Ton. I have tried (separately): enable_uart=1 dtparam=i2c_arm_baudrate=10000 and dtoverlay=i2c-bcm2708

on /boot/config.txt, but no success yet Is there a recommended baudrate for i2C on the PiJuice?

[tvoverbeek]

Note: standard baudrate for I2C is 100000 (100kHz), not 10 kHz

[PUW149]

I was trying it slower to see if that helped. Trying with a fresh SD card and vanilla Rpi Bullseye OS now.

[tvoverbeek]

First thing to check wrt I2C is if i2cdetect works (of course with something connected to the I2C bus).

[PUW149]

Nope, still nothing on I2C. Could be time for a new Rpi. Or could this be the PiJuice?

[tvoverbeek]

Do you have an other I2C peripheral which you could try?

[PUW149]

The only other I2C I have is an Element 14 Cirrus Logic Audio Card which I haven't used for years. My Rpi can't see that on I2C either, which supports this being an Rpi problem rather than a PiJuice problem