SAADC pulls too much current

[dkhayes117]

I'm using embedded rust for a project on the 9160.  If i configure any of the AIN0-AIN7 pins with the SAADC, my sleep current is 850 uA.  Default config is resistor bypass, 1/6 gain, 10 us time, no N channel.  I've tried different gains and pull up/downs but it doesn't help.  I have an off-board hall effect sensor that I will sample on one channel.  When that sensor is connected to an AIN pin, the sleep current drops to 115 uA.  I don't understand why this happens, even when the sensor isn't powered on.

The reason it matters is that I'm trying to read my battery voltage on AIN7, P0_20, which is an internal connection and when I add it to the SAADC, my sleep current goes from 115uA to ~800uA. 

[Kazi Afroza Sultana]

Hello,

We do not support RUST.

You have your own ADC drivers, so we require much more information as it seems there are hardware issues. 

"I have an off-board hall effect sensor that I will sample on one channel.  When that sensor is connected to an AIN pin, the sleep current drops to 115 uA.  I don't understand why this happens, even when the sensor isn't powered on.".

If the current consumption drops when you connect a signal to an analog pin, there must have something wrong with the HW. Are you using our DK? If it is not our DK, can send us the schematics and layout.  

You can read out the state of the SAADC registers after init and deinit and send us.

Thanks.

BR,

Kazi Afroza Sultana

[dkhayes117]

After further inspection, I believe the dev board I'm using has a design flaw with their battery measurement circuit which is causing the power discrepancy.

[Kazi Afroza Sultana]

Great that you have found the cause. Could you please share this briefly with the community?