
Under
development
1-76
Specifications in this manual are tentative and subject to change
Rev. H
Timer A
MITSUBISHI MICROCOMPUTERS
M30222 Group
SINGLE-CHIP 16-BIT CMOS MICROCOMPUTER
Table 1.26. Timer specifications in event counter mode (when not processing two-phase pulse signal)
Fig. 1.52. Timer Ai mode register in event counter mode
Note: This does not apply when the free-fun function is selected.
Item
Specification
Count source
External signals input to TAiIN pin (effective edge can be selected by software)
TB2 overflow, TAj overflow
Count operation
Up count or down count can be selected by external signal or software.
When the timer overflows or underflows, it reloads the reload register contents
before counting continues (Note)
Divide ratio
1/(FFFF16 - n+1) for up count
1/(n + 1) for down count
n: Set value
Count start condition
Count start flag is set (=1)
Count stop condition
Count start flag is reset (=0)
Interrupt request
generation timing
The timer overflows or underflows.
TAiIN pin function
Programmable I/O port or count source input
TAiOUT pin function
Programmable I/O port or pulse output, or up/down count select input
Read from timer
Count value can be read out by reading Timer Ai register
Write to timer
When counting stops
When a value is written to Timer Ai register, it is written to both reload register
and counter
When counting is 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).
Select function
Free-run count function
Even when the timer overflows or underflows, the reload register content is not
reloaded to it.
Pulse output function
Each timer the timer overflows or underflows, the TAiOUT pin s polarity is
reversed.
Timer Ai mode register
Note 1: In event counter mode, the count source is selected by the event / trigger select bit
(addresses 0382 16 and 038316).
Symbol
Address
When reset
TAiMR(i = 0, 1)
039616, 039716
0016
W
R
b7
b6
b5
b4
b3
b2
b1
b0
Operation mode select bit
0 1 : Event counter mode (Note 1)
b1 b0
TMOD0
MR0
Pulse output function
select bit
0 : Pulse is not output
(TA iOUT pin is a normal port pin)
1 : Pulse is output (Note 2)
(TA iOUT pin is a pulse output pin)
Count polarity
select bit (Note 3)
MR2
MR1
MR3
0 (Must always be fixed to “0” in event counter mode)
TCK0
Count operation type
select bit
01
0
0 : Counts external signal's falling edge
1 : Counts external signal's rising edge
Up/down switching
cause select bit
0 : Up/down flag's content
1 : TA iOUT pin's input signal (Note 4)
0 : Reload type
1 : Free-run type
Bit symbol
Bit name
Function
TCK1
Invalid in event counter mode
Can be “0” or “1”
TMOD1
Note 2: The settings of the corresponding port register and port direction register are invalid.
Note 3: Valid only when counting an external signal.
Note 4: When an "L" signal is input to the TAiOUT pin, the downcount is activated. When "H",
the upcount is activated. Set the corresponding port direction register to "0".