SPRUII0F May 2019 – June 2024 TMS320F28384D , TMS320F28384D-Q1 , TMS320F28384S , TMS320F28384S-Q1 , TMS320F28386D , TMS320F28386D-Q1 , TMS320F28386S , TMS320F28386S-Q1 , TMS320F28388D , TMS320F28388S
Burst mode can be used to sample a different set of signals on every other trigger. In the following example, ADCIN7 and ADCIN5 are converted on the first trigger from CPU1 Timer 2 and every other trigger thereafter. ADCIN2 and ACIN3 are converted on the second trigger from CPU1 Timer 2 and every other trigger thereafter. All signals are converted with 20 SYSCLK cycle wide acquisition windows, but different durations can be configured for each SOC as desired.
AdcaRegs.BURSTCTL.BURSTEN = 1; //Enable ADC burst mode
AdcaRegs.BURSTCTL.BURSTTRIG = 3; //CPU1 Timer 2 triggers burst of conversions
AdcaRegs.BURSTCTL.BURSTSIZE = 1; //conversion bursts are 1 + 1 = 2 conversions long
AdcaRegs.SOCPRICTL.bit.SOCPRIORITY = 12; //SOC0 to SOC11 are high priority
AdcaRegs.ADCSOC12CTL.bit.CHSEL = 7; //SOC12 converts ADCINA7
AdcaRegs.ADCSOC12CTL.bit.ACQPS = 19; //SOC12 uses sample duration of 20 SYSCLK cycles
AdcaRegs.ADCSOC13CTL.bit.CHSEL = 5; //SOC13 converts ADCINA5
AdcaRegs.ADCSOC13CTL.bit.ACQPS = 19; //SOC13 uses sample duration of 20 SYSCLK cycles
AdcaRegs.ADCSOC14CTL.bit.CHSEL = 2; //SOC14 converts ADCINA2
AdcaRegs.ADCSOC14CTL.bit.ACQPS = 19; //SOC14 uses sample duration of 20 SYSCLK cycles
AdcaRegs.ADCSOC15CTL.bit.CHSEL = 3; //SOC15 converts ADCINA3
AdcaRegs.ADCSOC15CTL.bit.ACQPS = 19; //SOC15 uses sample duration of 20 SYSCLK cycles
When the first CPU1 Timer 2 trigger is received, SOC12 and SOC13 are converted immediately if the ADC is idle. If the ADC is busy, SOC12 and SOC13 are converted once the SOCs gain priority. The results for SOC12 and SOC13 are in ADCRESULT12 and ADCRESULT13, respectively. After SOC13 completes, the round-robin pointer gives the highest priority to SOC14. Because of this, when the next CPU1 Timer 2 trigger is received, SOC14 and SOC15 is set as pending and eventually converted. The results for SOC14 and SOC15 are in ADCRESULT14 and ADCRESULT15, respectively. Subsequent triggers continue to toggle between converting SOC12 and SOC13, and converting SOC14 and SOC15.
While the above example toggles between two sets of conversions, three or more different sets of conversions can be achieved using a similar approach.