SPRUJ17I March 2022 – August 2025 AM2631 , AM2631-Q1 , AM2632 , AM2632-Q1 , AM2634 , AM2634-Q1
Each SOC can be configured to convert any of the ADC channels. This behavior is selected for SOCx by the ADCSOCxCTL.CHSEL register. Depending on the signal mode, the selection is different. For single-ended signal mode, the value in CHSEL selects a single pin as the input. For differential signal mode, the value in CHSEL selects an even-odd pin pair to be the positive and negative inputs. This is summarized in Table 7-112.
| Input Mode | CHSEL | Input | |
|---|---|---|---|
| Single-Ended | 0 | ADCIN0 | |
| 1 | ADCIN1 | ||
| 2 | ADCIN2 | ||
| 3 | ADCIN3 | ||
| 4 | ADCIN4 | ||
| 5 | ADCIN5 | ||
| Differential | CHSEL | Positive Input | Negative Input |
| 0 | ADCIN0 | ADCIN1 | |
| 1 | ADCIN1 | ADCIN0 | |
| 2 | ADCIN2 | ADCIN3 | |
| 3 | ADCIN3 | ADCIN2 | |
| 4 | ADCIN4 | ADCIN5 | |
| 5 | ADCIN5 | ADCIN4 | |
The ADCSOCxCTRL.EXTCHSEL field for each SOC can be used to automatically control an external mux with digital output pins ADCxEXTMUX[3:0]. This functionality enables the application to add additional ADC channels using an external mux, with minimal software overhead. The ADCxEXTMUX[3:0] outputs can be mapped to GPIO pins by configuring the GPIO output crossbar accordingly. The EXTCHSEL field supports up to 4-bit muxes, but fewer mux selection output pins can be configured if desired.
>To select a specific channel on the external mux, configure ADCSOCxCTRL.CHSEL to select the ADC pin that is connected to the mux output, and configure ADCSOCxCTRL.EXTCHSEL to select the desired mux input channel. There are a variety of potential mux topologies possible. A basic example can be a single external mux connected to a single ADC input channel. This setup is illustrated in ADC with External Input Mux
