TS80C51RA2-VIAR 데이터 시트보기 (PDF) - Atmel Corporation
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TS80C51RA2-VIAR Datasheet PDF : 74 Pages
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TS80C51RA2/RD2
TS83C51RB2/RC2/RD2
TS87C51RB2/RC2/RD2
6.5. Programmable Counter Array PCA
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 five compare/ capture modules. Its clock input
can be programmed to count any one of the following signals:
• Oscillator frequency ÷ 12 (÷ 6 in X2 mode)
• Oscillator frequency ÷ 4 (÷ 2 in X2 mode)
• Timer 0 overflow
• External input on ECI (P1.2)
Each compare/capture modules can be programmed in any one of the following modes:
• rising and/or falling edge capture,
• software timer,
• high-speed output, or
• pulse width modulator.
Module 4 can also be programmed as a watchdog timer (See Section "PCA Watchdog Timer", page 33).
When the compare/capture modules are programmed in the capture mode, software timer, or high speed
output mode, an interrupt can be generated when the module executes its function. All five modules plus the
PCA timer overflow share one interrupt vector.
The PCA timer/counter and compare/capture modules share Port 1 for external I/O. These pins are listed
below. If the port is not used for the PCA, it can still be used for standard I/O.
PCA component
16-bit Counter
16-bit Module 0
16-bit Module 1
16-bit Module 2
16-bit Module 3
16-bit Module 4
External I/O Pin
P1.2 / ECI
P1.3 / CEX0
P1.4 / CEX1
P1.5 / CEX2
P1.6 / CEX3
P1.7 / CEX4
The PCA timer is a common time base for all five modules (See Figure 7). 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:
• 1/12 the oscillator frequency. (Or 1/6 in X2 Mode)
• 1/4 the oscillator frequency. (Or 1/2 in X2 Mode)
• The Timer 0 overflow
• The input on the ECI pin (P1.2)
Rev. C - 06 March, 2001
23
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