When multiple SOC flags are set at the same time, one of two forms of priority determines the converted order. The default priority method is round-robin. In this scheme, no SOC has an inherent higher priority than another. Priority depends on the round-robin pointer (RRPOINTER). The RRPOINTER reflected in the ADCSOCPRIORITYCTL register points to the last SOC converted. The highest priority SOC is given to the next value greater than the RRPOINTER value, wrapping around back to SOC0 after SOC15. At reset the value is 16 since 0 indicates a conversion has already occurred. When RRPOINTER equals 16 the highest priority is given to SOC0. The RRPOINTER is reset when the ADC module is reset or when the reset value is written to the SOCPRICTL register. The ADC module is reset by writing and clearing the SOFTPRES bit corresponding to the ADC instance.

An example of the round-robin priority method is given in Figure 11-4.

The SOCPRIORITY field in the ADCSOCPRIORITYCTL register can be used to assign high priority from a single to all of the SOCs. When configured as high priority, an SOC interrupts the round-robin wheel after any current conversion completes and inserts in as the next conversion. After the conversion completes, the round-robin wheel continues where the conversion was interrupted. If two high priority SOCs are triggered at the same time, the SOC with the lower number takes precedence.

High priority mode is assigned first to SOC0, then in increasing numerical order. The value written in the SOCPRIORITY field defines the first SOC that is not high priority. In other words, if a value of 4 is written into SOCPRIORITY, then SOC0, SOC1, SOC2, and SOC3 are defined as high priority, with SOC0 the highest.

An example using high priority SOC’s is given in Figure 11-5.

Figure 11-4 Round Robin Priority Example

Figure 11-5 High Priority Example