Rainbow Electronics AT89C5131 User Manual

Page 71

AT89C5131

4136A–USB–03/03

The CMOD register includes three additional bits associated with the PCA (See
Figure 28 and Table 52).

•

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

•

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

•

The ECF bit 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 register contains the run control bit for the PCA and the flags for the PCA
timer (CF) and each module (see Table 53).

•

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
can only be cleared by software.

Reset Value = 000X 0000b
Not bit addressable

Table 53. CCON Register
CCON - PCA Counter Control Register (D8h)

–

CCF4

CCF3

CCF2

CCF1

CCF0

Bit

Number

Bit

Mnemonic 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.

CCF4

PCA Module 4 interrupt flag