C8051F388 Datasheet, PDF (262/285 Pages) –

C8051F388/9/A/B
26.3. Capture/Compare Modules
Each module can be configured to operate independently in one of six operation modes: edge-triggered
capture, software timer, high-speed output, frequency output, 8-bit pulse width modulator, or 16-bit pulse
width modulator. Each module has Special Function Registers (SFRs) associated with it in the CIP-51 sys-
tem controller. These registers are used to exchange data with a module and configure the module's mode
of operation. Table 26.2 summarizes the bit settings in the PCA0CPMn register used to select the PCA
capture/compare module’s operating mode. Setting the ECCFn bit in a PCA0CPMn register enables the
module's CCFn interrupt.
Table 26.2. PCA0CPM Bit Settings for PCA Capture/Compare Modules
Operational Mode
PCA0CPMn
Capture triggered by positive edge on CEXn
Capture triggered by negative edge on CEXn
Capture triggered by any transition on CEXn
Software Timer
High Speed Output
Frequency Output
8-Bit Pulse Width Modulator
16-Bit Pulse Width Modulator
Bit Number 7 6 5 4 3 2 1 0
XX1 0 0 0 0A
XX0 1 0 0 0A
XX1 1 0 0 0A
XB0 0 1 0 0A
XB0 0 1 1 0A
XB0 0 0 1 1A
0B0 0C0 1A
1B0 0C0 1A
Notes:
1. X = Don’t Care (no functional difference for individual module if 1 or 0).
2. A = Enable interrupts for this module (PCA interrupt triggered on CCFn set to 1).
3. B = When set to 0, the digital comparator is off. For high speed and frequency output modes, the associated
pin will not toggle. In any of the PWM modes, this generates a 0% duty cycle (output = 0).
4. C = When set, a match event will cause the CCFn flag for the associated channel to be set.
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