Internal Clock Mode (One-Shot Mode); Fig. 10.14 Count Operation In One-Shot Mode (Operation Of Software Trigger) - Fujitsu MB90420/5 (A) Series Hardware Manual

MB90420/5 (A) SERIES F

10.6.2 Internal Clock Mode (One-shot Mode)

The 16-bit counter is decremented synchronously with the internal count clock and a counter underflow
issues an interrupt request to the CPU. Also, a rectangular wave indicating counting is in progress can be
output from the TOT0/1 pin.
n Operation of internal clock mode (one-shot mode)
When counting is enabled (TMCSR0/1: CNTE = 1) and the timer is started using the software trigger bit
(TMCSR0/1: TRG) or an external trigger, counting is started. When the count enable bit and the software
trigger bit are set to 1 simultaneously, counting is started concurrently with the counter enabled. When the
value of the counter underflows (0000
point, the underflow interrupt request flag bit (UF) is set to 1 and when the interrupt request enable bit (INTE)
is 1, an interrupt request is issued. Also, a rectangular wave which indicates counting is in progress can be
output from the TOT pin.
• Operation of software trigger
The counter is started when 1 is written to the TRG bit of the timer control status register (TMCSR0/1L,
TMCSR0/1H). Figure 10.14 shows the software trigger operation at one-shot mode.
Count clock
Counter
Data load signal
UF bit
CNTE bit
TRG bit
TO pin
T : Machine cycle
* : It takes 1 T time from inputting the trigger to loading the reload data.

Fig. 10.14 Count Operation in One-shot Mode (Operation of Software Trigger)

2
MC-16LX FAMILY 16-BIT MICROCONTROLLERS HARDWARE MANUAL
→ FFFF
), the counter is stopped with the state of FFFF
H H
Reload
–1 0000
H
data
T*
Start trigger input wait
Reload
FFFF –1
H
data
10-20
H
0000 FFFF
H H
. At this