C8051F902-GD View Datasheet(PDF) - Silicon Laboratories

Part Name

Description

MFG CO.

C8051F902-GD

Single/Dual Battery, 0.9–3.6 V, 16–8 kB, SmaRTClock, 12/10-Bit ADC MCU

Silicon Laboratories 

C8051F91x-C8051F90x

26. Programmable Counter Array

The Programmable Counter Array (PCA0) provides enhanced timer functionality while requiring less CPU

intervention than the standard 8051 counter/timers. The PCA 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 seven sources: system clock, system clock divided by

four, system clock divided by twelve, the external oscillator clock source divided by 8, SmaRTClock divided

by 8 ('F912 and 'F902 devices only), Timer 0 overflows, 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 “26.3. Capture/Compare Modules” on page 296). The external

oscillator clock option is ideal for real-time clock (RTC) functionality, allowing the PCA to be clocked by a

precision external oscillator while the internal oscillator drives the system clock. The PCA is configured and

controlled through the system controller's Special Function Registers. The PCA block diagram is shown in

Figure 26.1.

Important Note: The PCA Module 5 may be used as a watchdog timer (WDT), and is enabled in this mode

following a system reset. Access to certain PCA registers is restricted while WDT mode is enabled.

See Section 26.4 for details.

SYSCLK/12

SYSCLK/4

Timer 0 Overflow

ECI

SYSCLK

PCA

CLOCK

MUX

16-Bit Counter/Timer

External Clock/8

SmaRTClock/8*

*Only available on ‘F912 and ‘F902 devices.

Capture/Compare

Module 0

Capture/Compare

Module 1

Capture/Compare

Module 2

Capture/Compare

Module 3

Capture/Compare

Module 4

Capture/Compare

Module 5 / WDT

Crossbar

Port I/O

Figure 26.1. PCA Block Diagram

292

Rev. 1.0

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