M30218 Datasheet, PDF (75/179 Pages) Mitsubishi Electric Semiconductor – M30218 Group

Timer A
Mitsubishi microcomputers
M30218 Group
SINGLE-CHIP 16-BIT CMOS MICROCOMPUTER
(1) Timer mode
In this mode, the timer counts an internally generated count source. (See Table FB-1.) Figure FB-6 shows
the timer Ai mode register in timer mode.
Table FB-1. Specifications of timer mode
Item
Specification
Count source
Count operation
f1, f8, f32, fC32
• 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
Write to timer
Count value can be read out by reading timer Ai register
• 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
Select function
(Transferred to counter at next reload time)
• 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
Timer Ai mode register
b7 b6 b5 b4 b3 b2 b1 b0
0
00
Symbol
TAiMR(i=0 to 4)
Address
When reset
039616 to 039A16 0016
Bit symbol
TMOD0
TMOD1
MR0
Bit name
Operation mode
select bit
Pulse output function
select bit
MR1
Gate function select bit
MR2
Function
b1 b0
0 0 : Timer mode
RW
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)
b4 b3
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)
MR3
TCK0
TCK1
0 (Must always be fixed to “0” in 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: The bit can be “0” or “1”.
Note 3: Set the corresponding port direction register to “0”.
Figure FB-6. Timer Ai mode register in timer mode
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