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MB90335 Series
13.3.4
Startup and Stop of Timer/Pulse Width Measurement
Start/restart/stop/forced stop of each operation are performed by using the PWCSR
bit15 and PWCSR bit14 (STRT and STOP bits).
■ Startup and Stop of Timer/Pulse Width Measurement
Functions are separated so that the STRT bit starts and restarts the timer/pulse width measurement and the
STOP bit forcibly stops the measurement when "0" is written in either one of bits. However, no function is
effective unless the values written in both bits are exclusive each other. When writing an instruction other
than bit manipulation instructions (one-byte instruction or more), the bits combination is always limited as
shown in Table 13.3-3.
Table 13.3-3 Function of STRT Bit and STOP Bit
STRT
0
1
When using a bit manipulation instruction (clear bit instruction), the hardware automatically writes it in the
combination as shown in Table 13.3-3 and no care is necessary.
■ Operation after Startup
Operations are as follow after starting the timer mode or the pulse width measurement mode.
●
Timer mode
The count operation begins at once.
●
Pulse width measurement mode
No count is performed until the measurement start edge is input. After the measurement start edge is
detected, the 16-bit up count timer is cleared to be 0000
■ Reactivation
Starting (writing "0" in the STRT bit) during the operation after starting the timer/pulse width measurement
mode is called as restarting.
Restarting performs the following operations depending on the mode:
●
Single shot timer mode
There is no influence in the operation.
●
Reload timer mode
Reload operates, and the operation is continued. Restarting at the same timing when an overflow occurs
sets the overflow flag (OVIR).
CM44-10137-6E
STOP
1
Startup/reactivation of timer/pulse width measurement
0
Compulsion stop of timer/pulse width measurement
FUJITSU MICROELECTRONICS LIMITED
CHAPTER 13 PWC TIMER
13.3 Movement of PWC Timer
Function
and the count starts.
H
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