High power consumption caused by I2C

[Hannibalhz]

Dear Nordic Engineer

  We recently encountered a problem about I2C.We have a smart door lock product, it has a fingerprint module that is an I2C interface, so we use the TWI function of NRF52832, but the problem we encounter now is that the average power consumption is only 50uA before TWI is turned on. After we initialize TWI with nrf_drv_twi_init(), we use nrf_drv_twi_enable() again to enable TWI. At this time, the average power consumption of our PCB board is about 500uA.At this time, I use nrf_drv_twi_uninit() and nrf_drv_twi_disable() to turn off TWI. According to the normal logic, the average power consumption should drop back to 50uA. But this does not seem to take effect, and its power consumption is still 500uA. We turned off peripherals such as LOG, ADC, PWM, and removed other components on the PCB, leaving only NRF52832 and its peripheral components. This problem still exists. Please help me analyze what is causing this?

  By the way, the information my colleague found is that this problem is caused by a bug in the use of GPIO interrupt and TWI, so after turning off I2C, he operated 0x40003FFC. At this time, the power consumption of the PCB can be reduced to 150uA, but This is still high. please help us.

Thanks you for your support & Best  regards！

[Vidar Berg]

Hello,

150-200 uA can be an indication of a floating input. Assume you don't have external pull-ups? Either way, please try the following perform the following sequence when disabling TWIM:

1. nrf_drv_twi_uninit(); // unitialize the driver and disable the peripheral

2. Configure the I2C pins back to their reset configuration (input, disconnect) by calling nrf_gpio_cfg_default(SCL_PIN); and nrf_gpio_cfg_default(SDA_PIN);

3. Perform the workaround for [89] GPIOTE: Static 400 µA current while using GPIOTE

*(volatile uint32_t *)0x40003FFC = 0;
*(volatile uint32_t *)0x40003FFC;
*(volatile uint32_t *)0x40003FFC = 1;

Hope this helps!

Best regards,

Vidar

[Hannibalhz]

Dear Vidar 

Thank your for your support，your suggestions is veryuseful.

Happly new year and best regard.