at89c51cc02ua-tdsum ATMEL Corporation, at89c51cc02ua-tdsum Datasheet - Page 114

• Manufacturer Part Number: at89c51cc02ua-tdsum
• Description: At89c51cc02, T89c51cc02 Enhanced 8-bit Microcontroller With Can Controller And Flash
• Manufacturer: ATMEL Corporation

Programmable
Counter Array (PCA)
PCA Timer
114
AT/T89C51CC02
The PCA provides more timing capabilities with less CPU intervention than the standard
timer/counters. Its advantages include reduced software overhead and improved accu-
racy. 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. Both modules and 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 pin is not used for the PCA, it can still be used for
standard I/O.
The PCA timer is a common time base for both 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:
•
•
•
•
PCA clock frequency/6 (See “clock” section)
PCA clock frequency/2
Timer 0 overflow
External input on ECI (P1.2)
Rising and/or falling edge capture,
Software timer
High-speed output
Pulse width modulator
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 Component
16-bit Module 0
16-bit Module 1
16-bit Counter
External I/O Pin
P1.3/CEX0
P1.4/CEX1
P1.2/ECI
4126L–CAN–01/08