C517A_99 Datasheet, PDF (108/218 Pages) Siemens Semiconductor Group – 8-Bit CMOS Microcontroller

On-Chip Peripheral Components
C517A
6.3.4.1 Timer 2 - Compare Function with Registers CRC, CC1 to CC4
The compare function of registers CRC and CC1 to CC3 is completely compatible with the
corresponding function of the C515/C515A. Registers CRC, CC1 to CC3 are permanently
connected to timer 2. All four registers are multifunctional as they additionally provide a capture or
a reload capability (CRC register only).
A general selection of the compare/capture function is done in register CCEN. For compare function
they can be used in compare mode 0 or 1, respectively. The compare mode is selected by setting
or clearing bit T2CM in special function register T2CON. Always two bits in register CCEN select
the CRC and CC1 to CC3 register functionality which are :
– Disable compare/capture mode (normal I/O at the pin)
– Capture enabled on rising edge at a pin
– Compare enabled (pin becomes a compare output)
– Capture enabled on a write operation into the low part register of CRC or CC1 to CC3
Special Function Register T2CON (Address C8H)
Special Function Register CCEN (Address C1H)
Reset Value : 00H
Reset Value : 00H
MSB
Bit No. CF_H
CE_H CD_H
CC_H
CB_H CA_H
C8H T2PS I3FR I2FR T2R1 T2R0 T2CM
C9_H
T2I1
LSB
C8_H
T1I0
T2CON
C1H
7
6
5
4
3
2
1
0
COCAH3 COCAL3 COCAH2 COCAL2 COCAH1 COCAL1 COCAH0 COCAL0
CCEN
The shaded bits are not used for compare/capture control.
Bit
T2CM
COCAH3,
COCAL3
Function
Compare mode control for CCR and CC1 to CC3 registers
When T2CM is cleared, compare mode 0 is selected.
When T2CM is set, compare mode 1 is selected.
Compare/capture mode for the CC register 3
COCAH3
0
0
1
1
COCAL3
0
1
0
1
Mode
Compare/capture disabled
Capture on rising edge at pin P1.3/INT6/CC3
Compare enabled
Capture on write operation into register CCL3
Semiconductor Group
6-42