M30218 Datasheet, PDF (79/179 Pages) Mitsubishi Electric Semiconductor – M30218 Group

Timer A
Mitsubishi microcomputers
M30218 Group
SINGLE-CHIP 16-BIT CMOS MICROCOMPUTER
(3) One-shot timer mode
In this mode, the timer operates only once. (See Table FB-4.) When a trigger occurs, the timer starts up and
continues operating for a given period. Figure FB-9 shows the timer Ai mode register in one-shot timer mode.
Table FB-4. Timer specifications in one-shot timer mode
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
Count stop condition
• The timer overflows
• The one-shot start flag is set (= 1)
• 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
TAiIN pin function
Programmable I/O port or trigger input
TAiOUT pin function
Programmable I/O port or pulse output
Read from timer
When timer Ai register is read, it indicates an indeterminate value
Write to timer
•When counting stopped
When a value is written to timer Ai register, it is written to both reload
register and counter
• When counting in progress
When a value is written to timer Ai register, it is written to only reload register
(Transferred to counter at next reload time)
Timer Ai mode register
b7 b6 b5 b4 b3 b2 b1 b0
0
10
Symbol
Address
When reset
TAiMR(i = 0 to 4) 039616 to 039A16 0016
Bit symbol
TMOD0
TMOD1
MR0
MR1
MR2
MR3
TCK0
TCK1
Bit name
Function
Operation mode select bit ^{b1 b0}
1 0 : One-shot timer mode
RW
Pulse output function
select bit
0 : Pulse is not output
(TAiOUT pin is a normal port pin)
1 : Pulse is output (Note 1)
(TAiOUT pin is a pulse output pin)
External trigger select
bit (Note 2)
0 : Falling edge of TAiIN pin's input signal (Note 3)
1 : Rising edge of TAiIN pin's input signal (Note 3)
Trigger select bit
0 : One-shot start flag is valid
1 : Selected by event/trigger select
register
0 (Must always be “0” in one-shot timer mode)
Count source select bit
b7 b6
0 0 : f1
0 1 : f8
1 0 : f32
1 1 : fC32
Note 1: The settings of the corresponding port register and port direction register are invalid
Note 2: Valid only when the TAiIN pin is selected by the event/trigger select bit
(addresses 038216 and 038316). If timer overflow is selected, this bit can be “1” or “0”.
Note 3: Set the corresponding port direction register to “0”.
Figure FB-9. Timer Ai mode register in one-shot timer mode
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