C8051F85X86X Datasheet, PDF (146/290 Pages) Silicon Laboratories – Low-Cost 8-bit MCU Family with up to 8 kB of Flash

C8051F85x/86x
20.3.4. High-Speed Output Mode
In High-Speed Output mode, a module’s associated CEXn pin is toggled each time a match occurs between the
PCA Counter and the module's 16-bit capture/compare register (PCA0CPHn and PCA0CPLn). When a match
occurs, the Capture/Compare Flag (CCFn) in PCA0CN is set to logic 1. An interrupt request is generated if the
CCFn interrupt for that module is enabled. The CCFn bit is not automatically cleared by hardware when the CPU
vectors to the interrupt service routine, and must be cleared by software. Setting the TOGn, MATn, and ECOMn
bits in the PCA0CPMn register enables the High-Speed Output mode. If ECOMn is cleared, the associated pin will
retain its state, and not toggle on the next match event.
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.
PCA0CPLn PCA0CPHn
ECOMn
(Compare Enable)
16-bit Comparator
MATn (Match Enable)
match
CCFn
(Interrupt Flag)
PCA Clock
PCA0L
PCA0H
Toggle
CEXn
TOGn (Toggle Enable)
Figure 20.4. PCA High-Speed Output Mode Diagram
Preliminary Rev 0.6
151