AT89C51RB2 Atmel Corporation, AT89C51RB2 Datasheet - Page 34

• Manufacturer Part Number: AT89C51RB2
• Manufacturer: Atmel Corporation

Specifications of AT89C51RB2

• Flash (kbytes): 16 Kbytes
• Max. Operating Frequency: 60 MHz
• Cpu: 8051-12C
• Max I/o Pins: 32
• Spi: 1
• Uart: 1
• Sram (kbytes): 1.25
• Self Program Memory: API
• Operating Voltage (vcc): 2.7 to 5.5
• Timers: 4
• Isp: UART
• Watchdog: Yes

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AT89C51RB2/RC2
Table 23. CCON Register
CCON – PCA Counter Control Register (D8h)
Reset Value = 000X 0000b
Bit addressable
The watchdog timer function is implemented in Module 4 (see Figure 14).
The PCA interrupt system is shown in Figure 12.
Number
CF
Bit
7
7
6
5
4
3
2
1
0
Mnemonic Description
CCF4
CCF3
CCF2
CCF1
CCF0
CR
Bit
CF
CR
6
-
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
4180E–8051–10/06
CCF0
0