AT89C51RE2 Atmel Corporation, AT89C51RE2 Datasheet - Page 86

• Manufacturer Part Number: AT89C51RE2
• Manufacturer: Atmel Corporation

Specifications of AT89C51RE2

• Flash (kbytes): 128 Kbytes
• Max. Operating Frequency: 60 MHz
• Cpu: 8051-12C
• Max I/o Pins: 34
• Spi: 1
• Uart: 2
• Sram (kbytes): 8.25
• Self Program Memory: API
• Operating Voltage (vcc): 2.7 to 5.5
• Timers: 4
• Isp: UART/OCD
• Watchdog: Yes

Figure 31. PCA Interrupt System
86
AT89C51RE2
PCA Timer/Counter
Module 0
Module 1
Module 2
Module 3
Module 4
CMOD.0
PCA Modules: each one of the five compare/capture modules has six possible functions. It can
perform:
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In addition, module 4 can be used as a Watchdog Timer.
Each module in the PCA has a special function register associated with it. These registers are:
CCAPM0 for module 0, CCAPM1 for module 1, etc. (See Table 56). The registers contain the
bits that control the mode that each module will operate in.
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Table 56 shows the CCAPMn settings for the various PCA functions.
16-bit Capture, positive-edge triggered
16-bit Capture, negative-edge triggered
16-bit Capture, both positive and negative-edge triggered
16-bit Software Timer
16-bit High Speed Output
8-bit Pulse Width Modulator
The ECCF bit (CCAPMn.0 where n=0, 1, 2, 3, or 4 depending on the module) enables the
CCF flag in the CCON SFR to generate an interrupt when a match or compare occurs in the
associated module.
PWM (CCAPMn.1) enables the pulse width modulation mode.
The TOG bit (CCAPMn.2) when set causes the CEX output associated with the module to
toggle when there is a match between the PCA counter and the module's capture/compare
register.
The match bit MAT (CCAPMn.3) when set will cause the CCFn bit in the CCON register to
be set when there is a match between the PCA counter and the module's capture/compare
register.
The next two bits CAPN (CCAPMn.4) and CAPP (CCAPMn.5) determine the edge that a
capture input will be active on. The CAPN bit enables the negative edge, and the CAPP bit
enables the positive edge. If both bits are set both edges will be enabled and a capture will
occur for either transition.
The last bit in the register ECOM (CCAPMn.6) when set enables the comparator function.
ECF
CF
ECCFn CCAPMn.0
CR
CCF4 CCF3 CCF2 CCF1 CCF0
IE.6
EC
IE.7
EA
priority decoder
CCON
0xD8
To Interrupt
7663E–8051–10/08