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CHAPTER 6 16-BIT TIMER/EVENT COUNTER
(1) Capture/compare register 00 (CR00)
CR00 is a 16-bit register which has the functions of both a capture register and a compare register. Whether
it is used as a capture register or as a compare register is set by bit 0 (CRC00) of capture/compare control
register 0 (CRC0).
When CR00 is used as a compare register, the value set in the CR00 is constantly compared with the 16-
bit timer register (TM0) count value, and an interrupt request (INTTM00) is generated if they match. It can
also be used as the register which holds the interval time when TM0 is set to interval timer operation, and
as the register which sets the pulse width when it is set to the PWM output operation.
When CR00 is used as a capture register, it is possible to select the valid edge of the INTP0/TI00 pin or the
INTP1/TI01 pin as the capture trigger. Setting of the INTP0/TI00 or INTP1/TI01 valid edge is performed by
means of external interrupt mode register 0 (INTM0).
If CR00 is specified as a capture register and capture trigger is specified to be the valid edge of the INTP0/
TI00 pin, the situation is as shown in the following table.
Table 6-5. INTP0/TI00 Pin Valid Edge and CR00 Capture Trigger Valid Edge
ES11
ES10
INTP0/TI00 Pin Valid Edge
CR00 Capture Trigger Valid Edge
0
0
Falling edge
Rising edge
0
1
Rising edge
Falling edge
1
0
Setting prohibited
1
1
Both rising and falling edges
No capture operation
CR00 is set by a 16-bit memory manipulation instruction.
After RESET input, the value of CR00 is undefined.
Cautions 1. Set a value other than 0000H to CR00. When the timer is used as an event counter,
therefore, one pulse cannot be counted.
2. If the new value of CR00 is less than the value of the 16-bit timer register (TM0), TM0
continues counting, overflows, and starts counting again from 0. If the new value of CR00
is less than the previous value, the timer must be restarted.
(2) Capture/compare register 01 (CR01)
CR01 is a 16-bit register which has the functions of both a capture register and a compare register. Whether
it is used as a capture register or a compare register is set by bit 2 (CRC02) of capture/compare control register
0 (CRC0).
When CR01 is used as a compare register, the value set in the CR01 is constantly compared with the 16-
bit timer register (TM0) count value, and an interrupt request (INTTM01) is generated if they match.
When CR01 is used as a capture register, it is possible to select the valid edge of the INTP0/TI00 pin as the
capture trigger. Setting of the INTP0/TI00 valid edge is performed by means of external interrupt mode register
0 (INTM0).
CR01 is set with a 16-bit memory manipulation instruction.
After RESET input, the value of CR01 is undefined.
Caution If a valid edge of the TI0/P00 pin is input while CR01 is being read, CR01 does not perform
the capture operation but holds the data. However, the interrupt request flag (PIF0), which
is set on detection of the valid edge, is set.