the connection of SAADC

[Kiyoshi Iwai]

Hello,

I would like to measure the voltage of circuit GND by using the embeded SAADC of nRF52832.

But unfortunately I have no vacancy of GPIO to connect GND.

Could you tell the way to connect GND and the ADC input at inside of IC, and to measure the voltage of GND?

Thanks,

Kiyoshi Iwai

[haakonsh]

Hey Kiyoshi,

"measure the voltage of GND?" I'm not quite sure what you mean. 

To set the negative input of a channel to GND you must initialize a channel by calling  nrf_drv_saadc_channel_init() with a nrf_saadc_channel_config_t where the mode set to nrf_saadc_mode_t NRF_SAADC_MODE_SINGLE_ENDED. Then the negative input will be connected to GND internally. You will still need some other voltage reference connected to the positive input. 

Cheers,

Håkon.

[Kiyoshi Iwai]

Hello Håkon,

Thank you for rapid reply.

I already know the way of single-end.

I just want to measure the DC offset of SAADC and to cancel the error,

but after re-considering, it's impossible to know the offset, I understood.

Sorry for strange question.

Thanks,

Kiyoshi Iwai

[haakonsh]

No problem Kiyoshi. 

FYI you can calibrate the offset with a call to nrf_drv_saadc_calibrate_offset. 

Cheers, 
Håkon