What is the pin for the battery voltage on nRF52pca1040 DK?

RE: What is the pin for the battery voltage on nRF52pca1040 DK?

ndarkness — Fri, 11 Aug 2017 09:51:38 GMT

I have remove the RETURN_IF_ERROR since they give me compilation errors

RE: What is the pin for the battery voltage on nRF52pca1040 DK?

Sigurd — Thu, 10 Aug 2017 15:38:13 GMT

If you are referring to the saadc_config symbol not found, it could be that is just goes out of scope. It's a chance you could "fix it" by configuring the optimization level in Project Properties(there is "Code Generation Options" under which there is "Optimisation Level"). But if you are not getting any compiler or linking errors, then there's nothing to fix.

I also see that you have removed the RETURN_IF_ERROR statements. I recommend checking all error codes with APP_ERROR_CHECK() in order to detect bugs and errors in your code.

APP_ERROR_CHECK(err_code);

RE: What is the pin for the battery voltage on nRF52pca1040 DK?

ndarkness — Thu, 10 Aug 2017 12:19:43 GMT

just added the pics

RE: What is the pin for the battery voltage on nRF52pca1040 DK?

ndarkness — Thu, 10 Aug 2017 12:17:08 GMT

Sorry I did a wrong screen shot, I have updated them. The failure seems to happen when calibrating the SAADC. I have updated the pics

RE: What is the pin for the battery voltage on nRF52pca1040 DK?

Sigurd — Thu, 10 Aug 2017 12:11:08 GMT

What do you mean by "SAADC seems to lose the pin referece to VDD." ? I don't see anything wrong in the images. After you call nrf_saadc_channel_config_t channel_config = NRF_DRV_SAADC_DEFAULT_CHANNEL_CONFIG_SE(batt_meas_init.adc_pin_no), pin_p in channel_config is set to NRF_SAADC_INPUT_VDD.

RE: What is the pin for the battery voltage on nRF52pca1040 DK?

ndarkness — Thu, 10 Aug 2017 11:55:14 GMT

Thanks Sigurd, I have followed your tip and used the nrf_saadc_channel_config_t channel_config = NRF_DRV_SAADC_DEFAULT_CHANNEL_CONFIG_SE(NRF_SAADC_INPUT_VDD); command, however I don't know while execution my SAADC seems to lose the pin referece to VDD. I have attached two images on the main post

RE: What is the pin for the battery voltage on nRF52pca1040 DK?

Sigurd — Thu, 10 Aug 2017 10:41:22 GMT

The SAADC can be configured to select AIN0 to AIN7 pins, or the VDD pin as input. See the pin map here.

RE: What is the pin for the battery voltage on nRF52pca1040 DK?

ndarkness — Thu, 10 Aug 2017 07:11:42 GMT

HI Sigurd, thanks for replying

Would it be possible to configure as well the GPIO to set VDD as input? Thus I would be able to check that my configuration is correct for the GPIOs, if I get the same reading as if I read directly from VDD.

RE: What is the pin for the battery voltage on nRF52pca1040 DK?

Sigurd — Wed, 09 Aug 2017 17:20:40 GMT

Hi,

You can configure the SAADC channel with VDD as input. You don’t have to use a GPIO for this.

nrf_saadc_channel_config_t channel_config =
    NRF_DRV_SAADC_DEFAULT_CHANNEL_CONFIG_SE(NRF_SAADC_INPUT_VDD);

The SAADC result can then be converted into volts, and further calculated into percentage based on a linearized version of the battery's discharge curve. Take look at how this is done in the saadc_event_handler() function in the e.g. the ble_app_proximty example in the SDK.

Code snippet from the example:

batt_lvl_in_milli_volts = ADC_RESULT_IN_MILLI_VOLTS(adc_result) +
                          DIODE_FWD_VOLT_DROP_MILLIVOLTS;
percentage_batt_lvl = battery_level_in_percent(batt_lvl_in_milli_volts);