AT89LP51RD2 Atmel Corporation, AT89LP51RD2 Datasheet - Page 97

• Manufacturer Part Number: AT89LP51RD2
• Manufacturer: Atmel Corporation

Specifications of AT89LP51RD2

• Flash (kbytes): 64 Kbytes
• Max. Operating Frequency: 20 MHz
• Cpu: 8051-1C
• Max I/o Pins: 42
• Spi: 1
• Twi (i2c): 1
• Uart: 1
• Adc Channels: 7
• Adc Resolution (bits): 10
• Adc Speed (ksps): 153.8
• Sram (kbytes): 2.25
• Self Program Memory: API
• Operating Voltage (vcc): 2.4 to 5.5
• Timers: 4
• Isp: SPI/OCD/UART
• Watchdog: Yes

15. Programmable Counter Array (PCA)
15.1
3714A–MICRO–7/11
PCA Timer/Counter
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:
Each compare/capture module can be programmed in any one of the following modes:
Module 4 can also be programmed as a watchdog timer (see
106).
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 one or several bits in the port are not used for the PCA, they can still be used
for standard I/O.
Table 15-1.
The PCA timer is a common time base for all five modules (see
source is determined from the CPS1 and CPS0 bits in the CMOD register
be programmed to run at:
• Peripheral clock frequency (F
• Peripheral clock frequency (F
• 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
• 1/2 the
• The Timer 0 overflow
• The input on the ECI pin (P1.2)
peripheral clock frequency (F
peripheral clock frequency (F
PCA I/O Pins
PCA Component
16-bit Module 0
16-bit Module 1
16-bit Module 2
16-bit Module 3
16-bit Counter
AT89LP51RD2/ED2/ID2 Preliminary
PERIPH
PERIPH
)
)
÷
÷
2
(TPS+1)
PERIPH
PERIPH
)
)
“PCA Watchdog Timer” on page
External I/O Pin
Figure
P1.3/CEX0
P1.4/CEX1
P1.5/CEX2
P1.6/CEX3
P1.2/ECI
15-1). The timer count
(Table
15-2) and can
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