Unde
Timer A
deeopmen
Mitsubishi microcomputers
M30201 Group
SINGLE-CHIP 16-BIT CMOS MICROCOMPUTER
56
Item
Specification
Count source
Count operation
f
1
, f
8
, f
32
, f
C32
The timer counts down
When the count reaches 0000
16
, the timer stops counting after reloading a new count
If a trigger occurs when counting, the timer reloads a new count and restarts counting
1/n n : Set value
An external trigger is input
The timer overflows
The one-shot start flag is set (= 1)
A new count is reloaded after the count has reached 0000
16
The count start flag is reset (= 0)
Interrupt request generation timing
The count reaches 0000
16
TA0
IN
pin function
Programmable I/O port or trigger input
TA0
OUT
pin function
Programmable I/O port or pulse output
Read from timer
When timer A0 register is read, it indicates an indeterminate value
Write to timer
When counting stopped
When a value is written to timer A0 register, it is written to both reload
register and counter
When counting in progress
When a value is written to timer A0 register, it is written to only reload register
(Transferred to counter at next reload time)
Divide ratio
Count start condition
Count stop condition
Table 1.16. Timer specifications in one-shot timer mode
Figure 1.44. Timer A0 mode register in one-shot timer mode
(3) One-shot timer mode
In this mode, the timer operates only once. (See Table 1.16.) When a trigger occurs, the timer starts up
and continues operating for a given period. Figure 1.44 shows the timer A0 mode register in one-shot
timer mode.
Bit name
Function
Bit symbol
TMOD0
Operation mode select bit
1 0 : One-shot timer mode
b1 b0
TMOD1
MR0
Pulse output function
select bit
0 : Pulse is not output
(TA0
OUT
pin is a normal port pin)
1 : Pulse is output (Note 1)
(TA0
OUT
pin is a pulse output pin)
MR2
MR1
MR3
0 (Must always be “0” in one-shot timer mode)
0 0 : f
1
0 1 : f
8
1 0 : f
32
1 1 : f
C32
b7 b6
TCK1
TCK0
Count source select bit
1 0
0
0 : One-shot start flag is valid
1 : Selected by event/trigger select
register
Trigger select bit
External trigger select
bit (Note 2)
0 : Falling edge of TA0
IN
pin's input signal (Note 3)
1 : Rising edge of TA0
IN
pin's input signal (Note 3)
W
R
A
A
A
A
A
A
A
A
Note 1: Set the corresponding port direction register to “1” (output mode).
Note 2:
Valid only when the TA0
IN
pin is selected by the event/trigger select bit
(addresses 0383
16
). If timer overflow is selected, this bit can be “1” or “0”.
Note 3: Set the corresponding port direction register to “0” (input mode).
Timer A0 mode register
Symbol
TA0MR
Address
0396
16
When reset
00
16
b7
b6
b5 b4
b3
b2
b1
b0