UPSD3422_06 Datasheet, PDF (181/293 Pages) STMicroelectronics – Turbo Plus Series Fast Turbo 8032 MCU with USB and Programmable Logic

uPSD34xx
Programmable counter array (PCA) with PWM
27.10
PWM mode - fixed frequency, 10-bit
The 10-bit PWM logic requires that all 3 TCMs in PCA0 or PCA1 operate in the same 10-bit
PWM mode. The 10-bit PWM operates in a similar manner as the 16-bit PWM, except the
PCACHm and PCACLm counters are reconfigured as 10-bit counters. The CAPCOMHn and
CAPCOMLn Registers become 10-bit registers.
PWM duty cycle of each TCM module can be specified in the 10-bit CAPCOMHn and
CAPCOMLn Registers. When the 10-bit PCA counter is equal or greater than the values in
the 10-bit registers CAPCOMHn and CAPCOMLn, the PWM output switches to a high state.
When the 10-bit PCA counter overflows, the PWM pin is switched to a logic low and starts
the next PWM pulse.
The most-significant 6 bits in the PCACHm counter and CAPCOMH Register are “Don’t
cares” and have no effect on the PWM generation.
27.11
Writing to capture/compare registers
When writing a 16-bit value to the PCA Capture/Compare registers, the low byte should
always be written first. Writing to CAPCOMLn clears the E_COMP Bit to '0'; writing to
CAPCOMHn sets E_COMP to '1' the largest duty cycle is 100% (CAPCOMHn CAPCOMLn
= 0x0000), and the smallest duty cycle is 0.0015% (CAPCOMHn CAPCOMLn = 0xFFFF). A
0% duty cycle may be generated by clearing the E_COMP Bit to ‘0’.
27.12
Control register bit definition
Each PCA has its own PCA_CONFIGn, and each module within the PCA block has its own
TCM_Mode Register which defines the operation of that module (see Table 96 on page 182
through Table 97 on page 182). There is one PCA_STATUS Register that covers both PCA0
and PCA1 (see Table 98 on page 183).
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