T89C51CC02 Atmel, T89C51CC02 Datasheet - Page 102

• Manufacturer Part Number: T89C51CC02
• Description: 8-Bit MCU
• Manufacturer: Atmel

T89C51CC02
16. Programmable Counter Array PCA
16.1. Introduction
The PCA provides more timing capabilities with less CPU intervention than the standard timer/counters. Its
advantages include reduced software overhead and improved accuracy. The PCA consists of a dedicated timer/
counter which serves as the time base for an array of two compare/capture modules. Its clock input can be
programmed to count any of the following signals:
Each compare/capture modules can be programmed in any one of the following modes:
When the compare/capture modules are programmed in capture mode, software timer, or high speed output mode,
an interrupt can be generated when the module executes its function. All two modules plus the PCA timer overflow
share one interrupt vector.
The PCA timer/counter and compare/capture modules share Port 1 for external I/Os. These pins are listed below.
If the port is not used for the PCA, it can still be used for standard I/O.
The PCA timer is a common time base for all modules (see Figure 9). The timer count source is determined from
the CPS1 and CPS0 bits in the CMOD SFR (see Table 8) and can be programmed to run at:
102
PCA component
16-bit Counter
16-bit Module 0
16-bit Module 1
1/6 the PCA clock frequency.
1/2 the PCA clock frequency.
the Timer 0 overflow.
the input on the ECI pin (P1.2).
PCA clock frequency / 6
PCA clock frequency / 2
Timer 0 overflow
External input on ECI (P1.2)
rising and/or trailing edge capture,
software timer,
high-speed output,
pulse width modulator.
External I/O Pin
P1.2 / ECI
P1.3 / CEX0
P1.4 / CEX1
Preliminary
Rev.A - May 17, 2001