Mitsubishi microcomputers
M16C / 62 Group
SINGLE-CHIP 16-BIT CMOS MICROCOMPUTER
Timer A
87
Item
Specification
Count source
f1, f8, f32, fC32
Count operation
Down count
When the timer underflows, it reloads 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 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)
Select function
Gate function
Counting can be started and stopped by the TAiIN pin’s input signal
Pulse output function
Each time the timer underflows, the TAiOUT pin’s polarity is reversed
(1) Timer mode
In this mode, the timer counts an internally generated count source. (See Table 1.17.1.) Figure 1.17.7
shows the timer Ai mode register in timer mode.
Table 1.17.1. Specifications of timer mode
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
(TAiIN 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 : f1
0 1 : f8
1 0 : f32
1 1 : fC32
b7 b6
TCK1
TCK0
Count source select bit
00
0
Figure 1.17.7. Timer Ai mode register in timer mode