
69
Mitsubishi microcomputers
M30240 Group
SINGLE-CHIP 16-BIT CMOS MICROCOMPUTER
Specifications REV. G
Specifications in this manual are tentative and subject to change
Timer A
1.2.21.1 Timer mode
In this mode, the timer counts an internally generated count source. See
Table 1.18 below.
Figure1.63 shows the timer Ai mode register in timer mode.
Figure 1.63: Timer Ai mode register in timer mode
Table 1.18:
Specifications of timer mode
Item
Specification
Count source
f1, f8, f32
Count operation
Down count
When the timer underflows, it loads the reload register contents before continuing counting
Divide ratio
1/(n+1) 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
When the timer underflows
TAiIN pin function
Programmable I/O port or gate input
TAiOUT pin function
Programmable I/O port or pulse output
Read from timer
Count value can be read out by reading timer Ai register
Write to timer
When counting is stopped and a value is written to timer Ai register, it is written to both reload
register and counter
When counting is in progress and a value is written to timer Ai register, it is written only to
reload register (to be transferred to counter at the next reload time)
Select function
Gate function
Counting can be started and stopped by TAiIN pin’s input signal
Pulse output function
Each time the timer underflows, the TAiOUT pin’s polarity is reversed
Note 1: The settings of the corresponding port register and port direction register are invalid.
Note 2: The bit can be “0” or “1”.
Note 3: Set the corresponding port direction register to “0”.
Timer Ai mode register
Symbol
Address
When reset
TAiMR(i=0 to 4)
039616 to 039A16
0016
Bit name
Function
Bit symbol
W
R
b7
b6
b5
b4
b3
b2
b1
b0
Operation mode select bit
0 0 : Timer mode
b1 b0
TMOD1
TMOD0
MR0
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)
Gate function select bit
0 X
(Note 2)
: Gate function not available
(TAi IN pin is a normal port pin)
1 0 : Timer counts only when TAiIN pin is
held “L” (Note 3)
1 1 : Timer counts only when TAiIN pin is
held “H” (Note 3)
b4 b3
MR2
MR1
MR3
0 (Must always be fixed to “0” in timer mode)
0 0 : f 1
0 1 : f 8
1 0 : f 32
1 1 : Reserved
b7 b6
TCK1
TCK0
Count source select bit
00
0