Multiple ADC reading - NCS

[Meh]

Hello everyone!

I'm trying to read 4 channels of ADC, and for future production, I'd have to read all 8.

There is two channels example, yet it isn't scalable. I'm thinking about building a dynamic setup based on the example, but it doesn't go so well due to the limits of specific macros in the given example code.

[ovrebekk]

Hi Tamir

It sounds a bit odd that the standard example shouldn't be scalable. The way it works is that it goes through all the channels defined in the device tree and configures each channel as required. 

As an example the nrf52840 overlay can be seen here, where 3 different channels are defined with different settings. In order to add more channels all you have to do is update the overlay, and the sample should handle the rest (just make sure to use each index between 0-7 only once). 

Best regards
Torbjørn

[Meh]

By trying your method, I'm getting various errors from CMake and a lack of definitions. I'm using NCS V1.9.1.

I'm attaching the list of errors and my project.

adc_extended.zip

[ovrebekk]

Hi

This feature was added in v2.1.0 of NCS, and won't work in v1.9.1 unfortunately. 

In v1.9.1 you would have to look at the battery sample. 

Alternatively it is possible to forego the Zephyr driver entirely and use the nrfx driver instead. There are some examples showing how to use the nrfx_saadc driver eavailable here. These are also written for a newer NCS version, but the nrfx drivers haven't changed much in that time API wise so I would expect the samples to run in older versions as well. 

Best regards
Torbjørn

[Meh]

adc_4.zip

So I did some googling. It builds well yet suffers from failure while trying to start channel 0. What did I miss here?

[ovrebekk]

Hi 

Which NCS version are you using to build it? 

I tried in v1.9.1, but it doesn't build. The .channel_cfgs field in the adc_sequence struct can't be found. 

Best regards
Torbjørn

[Meh]

I updated the code, and now it's compiling well, but when trying to see the nRF Terminal, I'm getting the following logs.

*** Booting Zephyr OS build v2.7.99-ncs1-1  ***
Device binded to ADC_0
[00:00:00.257,568] <err> os: ***** MPU FAULT *****
[00:00:00.257,568] <err> os:   Instruction Access Violation
[00:00:00.257,568] <err> os: r0/a1:  0x00000000  r1/a2:  0x20001958  r2/a3:  0x54f7fab5
[00:00:00.257,568] <err> os: r3/a4:  0x20001958 r12/ip:  0x00000000 r14/lr:  0x00000407
[00:00:00.257,598] <err> os:  xpsr:  0x61000000
[00:00:00.257,598] <err> os: Faulting instruction address (r15/pc): 0x54f7fab4
[00:00:00.257,598] <err> os: >>> ZEPHYR FATAL ERROR 0: CPU exception on CPU 0
[00:00:00.257,629] <err> os: Current thread: 0x20000420 (main)
[00:00:01.207,336] <err> fatal_error: Resetting system

The code now:

adc_4_v3.zip