High power consumption in sleep mode after using SAADC

RE: High power consumption in sleep mode after using SAADC

Kenneth — Mon, 02 Dec 2019 13:46:06 GMT

RE: High power consumption in sleep mode after using SAADC

piotrs — Mon, 02 Dec 2019 11:18:28 GMT

I used the last three days to narrow down the problem and more prescience tools to measure current. In fact, when I commented out nrfx_saadc_sample_convert() the compiler removed also a function call to the code that converts the read value to the voltage level. The function is the source of the high current consumption. It uses FPU for the computations. When I removed operations involving FPU the nRF52 consumes 2uA during sleep. When I disable hardware support for FPU (by removing options "-mfloat-abi=hard -mfpu=fpv4-sp-d16" from compiler and linker), I also got 2uA during sleep. With hard FPU, I get 3mA usage.

RE: High power consumption in sleep mode after using SAADC

Andreas — Thu, 28 Nov 2019 10:25:42 GMT

Hi,

OK, interesting, I thought this would solve it. I believe the issue is the DMA buffer enabling the SAADC, a workaround is described in this reply.

Best regards,

Andreas

RE: High power consumption in sleep mode after using SAADC

piotrs — Wed, 27 Nov 2019 13:50:59 GMT

Yes, I am using low power mode, by setting define (#define NRFX_SAADC_CONFIG_LP_MODE 1) and using NRFX_SAADC_DEFAULT_CONFIG when initializing SAADC.

RE: High power consumption in sleep mode after using SAADC

Andreas — Wed, 27 Nov 2019 13:37:26 GMT

Hi,

Did you enable low power mode when you initalized the SAADC?

Best regards,

Andreas