Renesas M16C Series User Manual

Timer A
M30240 Group
Rev.1.00 Sep 24, 2003 Page 163 of 360
2.2.2.9 One-shot timer mode - External trigger selected
In one-shot timer mode, select functions from those listed in Table 2.10 . An example using the indicated
options is described below. Figure 2.23 shows the operation timing, and Figure 2.24 shows the set-up
procedure.
Table 2.10: Timer A one-shot timer mode, external trigger functions
Note: j = i - 1, but j = 4 when i = 0; k = i + 1, but k = 0 when i = 4
Operation
(1) If the TAiIN pin input level changes from “L” to “H” with the count start flag set to “1”, the counter
performs a down count on the count source. At this time, the TAi
OUT
pin output level goes to “H” level.
(2) If the value of the counter becomes “0000
16
” the TAi
OUT
pin outputs an “L” level, and the counter
reloads the content of the reload register and stops counting. At this time, the Timer Ai interrupt re-
quest bit goes to “1”.
(3) If a trigger occurs while a count is in progress, the counter reloads the value of the reload register
again and continues counting. The reload timing is in step with the next count source input after the
trigger.
(4) Setting the count start flag to “0” causes the counter to stop and to reload the content of the reload
register. Also, the TAi
OUT
pin outputs an “L” level. At this time, the Timer Ai interrupt request bit goes
to “1”.
Figure 2.23: Operation timing of one-shot mode, external trigger selected
Item
Set-up
Count source O Internal count source (f1/f8/f32)
Pulse output function
No pulses output
O Pulses output
Count start condition
External trigger input (falling edge of input signal to the TAi
IN
pin)
O
External trigger input (rising edge of input signal to the TAi
IN
pin)
Timer overflow (TB2/TAj/TAk overflow)
Writing “1” to the one-shot start flag
FFFF16
n
0001
16
Timer Ai interrupt
request bit
Counter content (hex)
n = reload register content
Reload
Reload
(4) Stop count
One-shot pulse output
from TAi
OUT pin
"H"
1 / fi X (n)
"L"
1 / fi X (n+1)
TA i
IN pin
input signal
"H"
"L"
"1"
Cleared to "0" when interrupt request is accepted, or cleared by software
"0"
Count start flag
"1"
"0"
(2) Stop count
(1) Start count
(3) Start count
Time
Reload
Start count
Set to "1" by software
Trigger during count
Cleared to "0" by software

Renesas M16C Series Specifications

General

Brand	Renesas
Model	M16C Series
Category	Computer Hardware
Language	English