SWCU193 April 2023 CC2340R2 , CC2340R5 , CC2340R5-Q1
The ADC voltage reference (VR+) can be configured through the VRSEL bits in the MEMCTL register. Different reference sources can be selected for conversion on different channels. There are three options available for supplying a reference voltage to the ADC:
When supplying an external reference to the ADC, the VREF+ pin is connected to the reference source with the appropriate decoupling circuitry and the VREF- pin is connected to ground.
The internal reference (VREF) is a voltage reference module which is shared by multiple analog peripherals including the ADC. The internal reference is available on the VREF+ pin and it is recommended to connect a decoupling capacitor of specified value on the device pin. Please refer to the device-specific data sheet for the recommended capacitor value.