Renesas M16C Series User Manual

Timer A
M30240 Group
Rev.1.00 Sep 24, 2003 Page 149 of 360
2.2.2.2 Timer Mode with Gate Functions Selected
In timer mode, select functions from those listed in Table 2.2. An example using the indicated options is
described below. Figure 2.9 shows the operation timing, and Figure 2.10 shows the set-up procedure.
Table 2.2: Timer A timer mode and gate functions
Operation
(1) When the count start flag is set to “1” and the TAi
IN
pin inputs at “H” level, the counter performs a
down count on the count source.
(2) When the TAi
IN
pin inputs at “L” level, the counter holds its value and stops.
(3) If an underflow occurs, the content of the reload register is reloaded and the count continues. At
this time, the Timer Ai interrupt request bit goes to “1”.
(4) Setting the count start flag to “0” causes the counter to hold its value and to stop.
Note
• Make the pulse width of the signal input to the TAi
IN
pin not less than two cycles of the count source.
Figure 2.9: Timer mode timing and gate function operation
Item
Set-up
Count source O Internal count source (f1/f8/f32)
Pulse output function
O No pulses output
Pulses output
Gate function
No gate function
Performs count only for the period when the TAi
IN
pin is at “L”.
O
Performs count only for the period when the TAi
IN
pin is at “H”.
FFFF16
n
0000
16
Time
Count start flag
Timer Ai interrupt
request bit
“1”
“1”
Counter content (hex)
n = reload register content
TA i IN pin
input signal
(2) Stop count
“0”
“0”
Set to “1” by software
“H”
“L”
(4) Stop count
(1) Start count
Cleared to “0” when interrupt request is accepted, or cleared by software
(3) Underflow
Set to “1” by software
Cleared to “0” by
software
Start count again.

Renesas M16C Series Specifications

General

Brand	Renesas
Model	M16C Series
Category	Computer Hardware
Language	English