C8051F85X86X Datasheet, PDF (153/290 Pages) Silicon Laboratories – Low-Cost 8-bit MCU Family with up to 8 kB of Flash

C8051F85x/86x
20.4.4. 16-Bit Pulse Width Modulator Mode
A PCA module may also be operated in 16-Bit PWM mode. 16-bit PWM mode is independent of the other (8
through 11-bit) PWM modes. The entire PCA0CP register is used to determine the duty cycle in 16-bit PWM mode.
To output a varying duty cycle, new value writes should be synchronized with the PCA CCFn match flag to ensure
seamless updates.
16-Bit PWM mode is enabled by setting the ECOMn, PWMn, and PWM16n bits in the PCA0CPMn register. For a
varying duty cycle, the match interrupt flag should be enabled (ECCFn = 1 AND MATn = 1) to help synchronize the
capture/compare register writes. If the MATn bit is set to 1, the CCFn flag for the module will be set each time a
match edge or up edge occurs. The CF flag in PCA0CN can be used to detect the overflow or down edge.
Important Note About Capture/Compare Registers: When writing a 16-bit value to the PCA0 Capture/Compare
registers, the low byte should always be written first. Writing to PCA0CPLn clears the ECOMn bit to 0; writing to
PCA0CPHn sets ECOMn to 1.
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