NEC PD78P214 Manuale Utente
143
Chapter 7 Timer/Counter Units
7
7.2.3 8-Bit Timer/Counter 1 Control Registers
(1) Timer control register 1 (TMC1)
The TMC1 register is an 8-bit register for controlling the count operations of 8-bit timer 1 (TM1) and 8-bit timer
2 (TM2).
2 (TM2).
The lower 4 bits control the count operation of TM1 of 8-bit timer/counter 1. (The higher 4 bits control the count
operation of TM2 of 8-bit timer/counter 2.)
operation of TM2 of 8-bit timer/counter 2.)
The TMC1 register allows both read and write operations using an 8-bit manipulation instruction. Fig. 7-44
shows the format of the TMC1 register.
shows the format of the TMC1 register.
When the RESET signal is applied, the TMC1 register is cleared to 00H.
Fig. 7-44 Format of Timer Control Register 1 (TMC1)
7
6
5
4
3
2
1
0
CE2
OVF2 CMD2
0
CE1
OVF1
0
0
TMC1
OVF1
0
1
1
0
CE1
TM1 overflow flag
Overflow does not occur
Overflow occurs
(countiing up from FFH to 00H)
(countiing up from FFH to 00H)
TM1 counting control
Clears and stops counting
Enables counting
These bits control counting for 8-bit timer/
counter 2 (TM2) (see Fig. 7-67).
counter 2 (TM2) (see Fig. 7-67).
Remark The OVF1 bit can be reset only by software.
(2) Prescaler mode register 1 (PRM1)
The PRM1 register is an 8-bit register used to specify a count clock for 8-bit timer 1 (TM1) and 8-bit timer 2
(TM2).
(TM2).
The lower 4 bits are used to specify a count clock for TM1 of 8-bit timer/counter 1. (The higher 4 bits are used
to specify a count clock for TM2 of 8-bit timer/counter 2.)
to specify a count clock for TM2 of 8-bit timer/counter 2.)
The PRM1 register allows only write operation using an 8-bit manipulation instruction. Fig. 7-45 shows the
format of the PRM1 register.
format of the PRM1 register.
When the RESET signal is applied, the PRM1 register is cleared to 00H.