AT89C51RD2 Atmel Corporation, AT89C51RD2 Datasheet - Page 38

• Manufacturer Part Number: AT89C51RD2
• Manufacturer: Atmel Corporation

Specifications of AT89C51RD2

• Flash (kbytes): 64 Kbytes
• Max. Operating Frequency: 60 MHz
• Cpu: 8051-12C
• Max I/o Pins: 32
• Spi: 1
• Uart: 1
• Sram (kbytes): 2
• Self Program Memory: API
• Operating Voltage (vcc): 2.7 to 5.5
• Timers: 4
• Isp: UART
• Watchdog: Yes

38
AT89C51RD2/ED2
Table 13-2.
CCON - PCA Counter Control Register (D8h)
Reset Value = 00X0 0000b
Bit addressable
The watchdog timer function is implemented in Module 4 (See Figure 13-4).
The PCA interrupt system is shown in Figure 13-2.
Number
CF
Bit
7
7
6
5
4
3
2
1
0
Mnemonic
CCON Register
CCF4
CCF3
CCF2
CCF1
CCF0
CR
Bit
CF
CR
6
-
Description
PCA Counter Overflow flag
Set by hardware when the counter rolls over. CF flags an interrupt if bit ECF in CMOD is
set. CF
may be set by either hardware or software but can only be cleared by software.
PCA Counter Run control bit
Must be cleared by software to turn the PCA counter off.
Set by software to turn the PCA counter on.
Reserved
The value read from this bit is indeterminate. Do not set this bit.
PCA Module 4 interrupt flag
Must be cleared by software.
Set by hardware when a match or capture occurs.
PCA Module 3 interrupt flag
Must be cleared by software.
Set by hardware when a match or capture occurs.
PCA Module 2 interrupt flag
Must be cleared by software.
Set by hardware when a match or capture occurs.
PCA Module 1 interrupt flag
Must be cleared by software.
Set by hardware when a match or capture occurs.
PCA Module 0 interrupt flag
Must be cleared by software.
Set by hardware when a match or capture occurs.
5
-
CCF4
4
CCF3
3
CCF2
2
CCF1
1
4235K–8051–05/08
CCF0
0