M16C62A Datasheet, PDF (79/242 Pages) Mitsubishi Electric Semiconductor – SINGLE-CHIP 16-BIT CMOS MICROCOMPUTER

Timer A
Mitsubishi microcomputers
M16C / 62A Group (80-pin)
SINGLE-CHIP 16-BIT CMOS MICROCOMPUTER
(4) Pulse width modulation (PWM) mode
In this mode, the timer outputs pulses of a given width in succession. (See Table 1.13.5.) In this mode, the
counter functions as either a 16-bit pulse width modulator or an 8-bit pulse width modulator. Timer A1
and A2 have no output pin, so it doesn't work in this mode. Figure 1.13.11 shows the timer Ai mode
register in pulse width modulation mode. Figure 1.13.12 shows the example of how a 16-bit pulse width
modulator operates. Figure 1.13.13 shows the example of how an 8-bit pulse width modulator operates.
Table 1.13.5. Timer specifications in pulse width modulation mode
Item
Specification
Count source
Count operation
16-bit PWM
8-bit PWM
Count start condition
Count stop condition
Interrupt request generation timing
TAiIN pin function
TAiOUT pin function
Read from timer
Write to timer
f1, f8, f32, fC32
• The timer counts down (operating as an 8-bit or a 16-bit pulse width modulator)
• The timer reloads a new count at a rising edge of PWM pulse and continues counting
• The timer is not affected by a trigger that occurs when counting
• High level width n / fi n : Set value
• Cycle time (2¹⁶-1) / fi fixed
• High level width n (m+1) / fi n : values set to timer Ai register’s high-order address
• Cycle time
(2⁸-1) (m+1) / fi m : values set to timer Ai register’s low-order address
• External trigger is input
• The timer overflows
• The count start flag is set (= 1)
• The count start flag is reset (= 0)
PWM pulse goes “L”
Programmable I/O port or trigger input
Pulse output
When timer Ai register is read, it indicates an indeterminate value
• 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)
Note: Timer A1 and A2 do not have I/O port (TAiIN and TAiOUT).
Timer Ai mode register
b7 b6 b5 b4 b3 b2 b1 b0
11 1
Symbol
Address
When reset
TAiMR(i=0 to 4) 039616 to 039A16 0016
Bit symbol
TMOD0
TMOD1
MR0
MR1
Bit name
Function
RW
Operation mode
select bit
b1 b0
1 1 : PWM mode
1 (Must always be “1” in PWM mode) (Note 3)
External trigger select
bit (Note 1,3)
0: Falling edge of TAiIN pin's input signal (Note 2)
1: Rising edge of TAiIN pin's input signal (Note 2)
MR2
Trigger select bit
0: Count start flag is valid
1: Selected by event/trigger select bits
MR3
TCK0
TCK1
16/8-bit PWM mode
select bit
Count source select bit
0: Functions as a 16-bit pulse width modulator
1: Functions as an 8-bit pulse width modulator
b7 b6
0 0 : f1
0 1 : f8
1 0 : f32
1 1 : fC32
Note 1: 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 2: Set the corresponding port direction register to “0”.
Note 3: Set these bits "0" in timer A1 and A2 mode registers.
Figure 1.13.11. Timer Ai mode register in pulse width modulation mode
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