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Mitsubishi microcomputers
M30201 Group
SINGLE-CHIP 16-BIT CMOS MICROCOMPUTER
Timer A
56
Item
Specification
Count source
f1, f8, f32, fC32
Count operation
The timer counts down
When the count reaches 000016, the timer stops counting after reloading a new count
If a trigger occurs when counting, the timer reloads a new count and restarts counting
Divide ratio
1/n
n : Set value
Count start condition
An external trigger is input
The timer overflows
The one-shot start flag is set (= 1)
Count stop condition
A new count is reloaded after the count has reached 000016
The count start flag is reset (= 0)
Interrupt request generation timing
The count reaches 000016
TA0IN pin function
Programmable I/O port or trigger input
TA0OUT 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)
Table 1.15. 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 1.15.) 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
Operation mode select bit
1 0 : One-shot timer mode
b1 b0
TMOD1
TMOD0
MR0
Pulse output function
select bit
0 : Pulse is not output
(TA0OUT pin is a normal port pin)
1 : Pulse is output (Note 1)
(TA0OUT pin is a pulse output pin)
MR2
MR1
MR3
0 (Must always be “0” in one-shot timer mode)
0 0 : f1
0 1 : f8
1 0 : f32
1 1 : fC32
b7 b6
TCK1
TCK0
Count source select bit
10
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 TA0IN pin's input signal (Note 3)
1 : Rising edge of TA0IN pin's input signal (Note 3)
W
R
Note 1: Set the corresponding port direction register to “1” (output mode).
Note 2: Valid only when the TA0IN pin is selected by the event/trigger select bit
(addresses 038316). 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
Address
When reset
TA0MR
039616
0016
b7
b6
b5 b4
b3
b2
b1
b0