AT80C51RA2 データシートの表示（PDF） - Atmel Corporation

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AT80C51RA2

High Performance 8-bit Microcontrollers

Atmel Corporation 

• The CIDL bit which allows the PCA to stop during idle mode.

• The WDTE bit which enables or disables the watchdog function on module 4.

• The ECF bit which when set causes an interrupt and the PCA overflow flag CF (in the CCON

SFR) to be set when the PCA timer overflows.

The CCON SFR contains the run control bit for the PCA and the flags for the PCA timer (CF)

and each module (Refer to Table 6-5).

• Bit CR (CCON.6) must be set by software to run the PCA. The PCA is shut off by clearing this

bit.

• Bit CF: The CF bit (CCON.7) is set when the PCA counter overflows and an interrupt will be

generated if the ECF bit in the CMOD register is set. The CF bit can only be cleared by

software.

• Bits 0 through 4 are the flags for the modules (bit 0 for module 0, bit 1 for module 1, etc.) and

are set by hardware when either a match or a capture occurs. These flags also can only be

cleared by software.

Table 6-5. CCON: PCA Counter Control Register

CCON

Address 0D8H

CF

CR

-

Reset value

0

0

X

CCF4

0

CCF3

0

CCF2

0

CCF1

0

CCF0

0

Symbol

Function

PCA Counter Overflow flag. Set by hardware when the counter rolls over. CF flags

CF

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.

CR

PCA Counter Run control bit. Set by software to turn the PCA counter on. Must be cleared by

software to turn the PCA counter off.

-

Not implemented, reserved for future use. (1)

CCF4

PCA Module 4 interrupt flag. Set by hardware when a match or capture occurs. Must be cleared by

software.

CCF3

PCA Module 3 interrupt flag. Set by hardware when a match or capture occurs. Must be cleared by

software.

CCF2

PCA Module 2 interrupt flag. Set by hardware when a match or capture occurs. Must be cleared by

software.

CCF1

PCA Module 1 interrupt flag. Set by hardware when a match or capture occurs. Must be cleared by

software.

CCF0

PCA Module 0 interrupt flag. Set by hardware when a match or capture occurs. Must be cleared by

software.

1.

User software should not write 1s to reserved bits. These bits may be used in future 8051 family

products to invoke new features. In that case, the reset or inactive value of the new bit will be 0,

and its active value will be 1. The value read from a reserved bit is indeterminate.

The watchdog timer function is implemented in module 4 (See Figure 6-7).

The PCA interrupt system is shown in Figure 6-5.

26 AT/TS8xC51Rx2

4188F–8051–01/08

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