C8051F58X Datasheet, PDF (331/356 Pages) Silicon Laboratories – Programmable hysteresis and response time Configurble as interrupt or reset source Low current

C8051F58x/F59x
29. Programmable Counter Array 1 (PCA1)
The Programmable Counter Array (PCA1) provides enhanced timer functionality while requiring less CPU
intervention than the standard 8051 counter/timers. PCA1 consists of a dedicated 16-bit counter/timer and
six 16-bit capture/compare modules. Each capture/compare module has its own associated I/O line
(CEXn) which is routed through the Crossbar to Port I/O when enabled. The counter/timer is driven by a
programmable timebase that can select between eight sources: system clock, system clock divided by
four, system clock divided by twelve, the external oscillator clock source divided by 8, Timer 0, 4, or 5 over-
flows, or an external clock signal on the ECI input pin. Each capture/compare module may be configured to
operate independently in one of six modes: Edge-Triggered Capture, Software Timer, High-Speed Output,
Frequency Output, 8 to 11-Bit PWM, or 16-Bit PWM (each mode is described in Section
“29.3. Capture/Compare Modules” on page 334). The external oscillator clock option is ideal for real-time
clock (RTC) functionality, allowing PCA1 to be clocked by a precision external oscillator while the internal
oscillator drives the system clock. PCA1 is configured and controlled through the system controller's Spe-
cial Function Registers. The PCA1 block diagram is shown in Figure 29.1
Note: PCA0 and PCA1 are fully independent peripherals. PCA0 offers channels CEX0 - CEX5, and PCA1 offers
channels CEX6-CEX11. PCA0 and PCA1 are identical, except that PCA0 Module 5 may be used as a
watchdog timer.
SYSCLK/12
SYSCLK/4
Timer 0 Overflow
ECI1
SYSCLK
External Clock/8
Timer 4 Overflow
Timer 5 Overflow
PCA1
CLOCK
MUX
16-Bit Counter/Timer
Capture/Compare
Module 6
Capture/Compare
Module 7
Capture/Compare
Module 8
Capture/Compare
Module 9
Capture/Compare
Module 10
Capture/Compare
Module 11
Crossbar
Port I/O
Figure 29.1. PCA1 Block Diagram
Rev. 1.2
331