Texas Instruments TMS320C6745 DSP - ECAP Initialization for APWM Mode

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SPRUH91D–March 2013–Revised September 2016
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Enhanced Capture (eCAP) Module
Table 13-5. ECAP Initialization for APWM Mode
Register Bit Value
CAP1 CAP1 0x1000
CTRPHS CTRPHS 0x0
ECCTL2 CAP_APWM EC_APWM_MODE
ECCTL2 APWMPOL EC_ACTV_HI
ECCTL2 SYNCI_EN EC_DISABLE
ECCTL2 SYNCO_SEL EC_SYNCO_DIS
ECCTL2 TSCTRSTOP EC_RUN
Example 13-5. Code Snippet for APWM Mode
// Code snippet for APWM mode Example 1
// Run Time (Instant 1, e.g. ISR call)
//======================
ECAPxRegs.CAP2 = 0x300; // Set Duty cycle i.e. compare value
// Run Time (Instant 2, e.g. another ISR call)
//======================
ECAPxRegs.CAP2 = 0x500; // Set Duty cycle i.e. compare value
13.3.5.2 Multichannel PWM Generation with Synchronization Example
Figure 13-15 takes advantage of the synchronization feature between eCAP modules. Here 4 independent
PWM channels are required with different frequencies, but at integer multiples of each other to avoid
"beat" frequencies. Hence one eCAP module is configured as the Master and the remaining 3 are Slaves
all receiving their synch pulse (CTR = PRD) from the master. Note the Master is chosen to have the lower
frequency (F1 = 1/20,000) requirement. Here Slave2 Freq = 2 × F1, Slave3 Freq = 4 × F1 and Slave4
Freq = 5 × F1. Note here values are in decimal notation. Also, only the APWM1 output waveform is
shown.