M30218 Datasheet, PDF (80/179 Pages) Mitsubishi Electric Semiconductor – M30218 Group

Timer A
Mitsubishi microcomputers
M30218 Group
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 FB-5.) In this mode, the counter
functions as either a 16-bit pulse width modulator or an 8-bit pulse width modulator. Figure FB-10 shows the
timer Ai mode register in pulse width modulation mode. Figure FB-11 shows the example of how a 16-bit pulse
width modulator operates. Figure FB-12 shows the example of how an 8-bit pulse width modulator operates.
Table FB-5. Timer specifications in pulse width modulation mode
Item
Specification
Count source
Count operation
16-bit PWM
8-bit PWM
Count start condition
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 X (m+1) / fi n : values set to timer Ai register’s high-order address
•Cycle time (2⁸-1) X (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)
Count stop condition
•The count start flag is reset (= 0)
Interrupt request generation timing PWM pulse goes “L”
TAiIN pin function
Programmable I/O port or trigger input
TAiOUT pin function
Pulse output
Read from timer
Write to timer
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)
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 fixed to “1” in PWM mode)
External trigger select
bit (Note 1)
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 register
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”.
Figure FB-10. Timer Ai mode register in pulse width modulation mode
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