npm1300 readings delayed by one measurement

RE: npm1300 readings delayed by one measurement

helsing — Thu, 19 Dec 2024 14:57:35 GMT

[quote user="dave_s"]If I want the immediate results can I call sensor_fetch() twice back to back? Do I need to leave any time in between for the ADC to process?[/quote]

This would work, however, it is not ideal in terms of energy consumption.

The conversion time, t_conv is 250 µs per sample. Four samples are triggered by the fetch() function (battery voltage, battery current, battery ntc, die temperature).

On the nPM1300 EK we trigger sampling, wait for it to be done, and then read out the result. This way one will get the latest result.

It is possible to do ADC readings from the application with manual I2C reads/writes. We have functions for this in npm1300.h: mfd_npm1300_reg_write and mfd_npm1300_reg_read.

RE: npm1300 readings delayed by one measurement

dave — Wed, 18 Dec 2024 16:22:00 GMT

Thanks

Is that the desired behavior or a bug?

If I want the immediate results can I call sensor_fetch() twice back to back? Do I need to leave any time in between for the ADC to process?

RE: npm1300 readings delayed by one measurement

helsing — Wed, 18 Dec 2024 11:18:07 GMT

Hi Dave,

It seems like the behavior is due to the way the driver was implemented. When you call the sensor_fetch() function, the nPM1300 driver reads out the ADC result registers and then triggers a new conversion. Consequently, the sensor channel results you obtain will actually reflect the results from the previous sensor_fetch() call, rather than the most recent one you just initiated.

RE: npm1300 readings delayed by one measurement

helsing — Fri, 13 Dec 2024 13:25:46 GMT

Hi Dave,

We are looking into this and will get back to you next week.