Hi! I’m using nRF52832 dev board and battery babysitter. I’m trying to communicate with the on-board BQ27441-G1A fuel gauge via I2C, but it’s giving me a hard time.
While the I2C signals on the nRF52 work every time, the fuel gauge responds with ACK only about half the time. E.g. when I try to unlock the fuel gauge’s config, it sometimes works, but half the time when sending the address byte, there is no response from the board (NACK) without any electrical or software changes. It’s completely random.
Although the BQ27441-G1A runs at 1.8V, its I2C and GPOUT pins are tolerant up to 5V. That’s where the VPU pin comes into play. The VPU pin, short for VPULL-UP, is the pull-up voltage for the open-drain SDA and SCL pins. This pin is an input, and should be connected to the operating voltage of your system – 3.3V, 5V, etc. A voltage supply is required on this pin, unless you have pull-up’s on the I2C bus elsewhere in your project.
Perhaps ensure that you are supplying a voltage to this VPU pin, and/or try enabling pull-up resistors on the nrf board?
Otherwise, try sharing a couple photos of your wiring/setup