Renesas M16C FAMILY, User Manual

Page: 23 / 369

Rev.2.00 Oct 16, 2006 page 12 of 354
REJ09B0340-0200
M30245 Group 2. Timer A
In timer mode, choose functions from those listed in Table 2.2.1. Operations of the circled items are
described below. Figure 2.2.6 shows the operation timing, and Figure 2.2.7 shows the set-up procedure.
Item
Count source
Pulse output function
Gate function
Set-up
O
O
O
Internal count source (f
1
/ f
8
/ f
32
/ fc
32
)
No pulses output
Pulses output
No gate function
Performs count only for the period in which the TAi
IN
pin is at “L” level
Performs count only for the period in which the TAi
IN
pin is at “H” level
Operation (1) Setting the count start flag to “1” causes the counter to perform a down count on the count
source.
(2) 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”.
(3) Setting the count start flag to “0” causes the counter to hold its value and to stop.
2.2.2 Operation of Timer A (timer mode)
Table 2.2.1. Choosed functions
Figure 2.2.6. Operation timing of timer mode
FFFF
16
n
0000
16
Time
Start count again
Count start flag
Timer Ai interrupt
request bit
“1”
“1”
Counter content (hex)
n = reload register content
Set to “1” by software
“0”
“0”
Set to “1” by software
Cleared to “0” by
software
Cleared to “0” when interrupt request is accepted, or cleared by software
(1) Start count (2) Underflow (3) Stop count