RE: Questions about nRF52840 ADC

Jared — Tue, 11 Oct 2022 13:23:18 GMT

Hi there,

Could you share a minimal example that reproduces the issue on a development kit?

regards

Jared

RE: Questions about nRF52840 ADC

ericwelch1 — Mon, 10 Oct 2022 22:02:25 GMT

When using an apparently unsupported Reference, the error is -21 (which I understand is EINVALID, meaning that the setup isn't supported)

We are using a custom board, but the clock and power duplicate the NRF9160_nRF52840 as closely as possible. We have a custom AFE connected to AIN6 and AIN7

RE: Questions about nRF52840 ADC

Jared — Thu, 08 Sep 2022 09:37:41 GMT

Hi,

[quote user=""]1. What is the best Nordic example for ADC on this platform?[/quote]

I would suggest this one.

[quote user=""]2. While we have been able to use add_read(), the call add_read_async() doesn't appear to exist in the 1.8.0 SDK. Why?[/quote]

Strange, both should be available in NCS v.1.8.0. Are you getting any specific errors when you try to use it?

[quote user=""]

3. We have experimented with the ADC reference "Internal" and the accessor suggests that this is 600 mV. However, using ADC_REF_VDD_1 or ADC_REF_VDD_1_2 produce errors when adc_read() is called. Why is this?

prj.conf includes

# ADC
CONFIG_ADC=y
CONFIG_ADC_NRFX_SAADC=y

zephyr.dts includes:

adc: adc@40007000 {
compatible = "nordic,nrf-saadc";
reg = < 0x40007000 0x1000 >;
interrupts = < 0x7 0x1 >;
status = "okay";
label = "ADC_0";
#io-channel-cells = < 0x1 >;
};

[/quote]

Exactly what errors is returned?

[quote user=""]4. we are using pins AIN6 and AIN7. We always get data, but it is apparently not always related to the voltage on the input pin.[/quote]

Are you using a custom board or the PCA10056 development kit?

regards

Jared n