M16C6K9 Datasheet, PDF (89/292 Pages) Renesas Technology Corp – SINGLE-CHIP 16-BIT CMOS MICROCOMPUTER

M16C/6K9 Group
Timer A
(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. Fig.FB-11
shows the timer Ai mode register in pulse width modulation mode. Fig.FB-12 shows the example of how a
16-bit pulse width modulator operates. Fig.FB-13 shows the example of how an 8-bit pulse width modulator
operates.
Table.FB-5 Timer specifications in pulse width modulation mode
Item
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
Specification
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)
The falling edge of PWM pulse
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)
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
MR2
Bit name
Function
Operation mode selection ^{b1 b0}
bits
1 1 : PWM mode
1 (Must always be “1” in PWM mode)
External trigger selection 0: Falling edge of TAiIN pin's input signal (Note 2)
bit (Note 1)
1: Rising edge of TAiIN pin's input signal (Note 2)
RW
Trigger selection bit
0: Count start flag is valid
1: Selected by event/trigger selection register
MR3
TCK0
TCK1
16/8-bit PWM mode
selection bit
0: Functions as a 16-bit pulse width modulator
1: Functions as an 8-bit pulse width modulator
b7 b6
Count source selection bits _{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 selection 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”.
Fig.FB-11 Timer Ai mode register in pulse width modulation mode
Rev.1.00 Jun 06, 2003 page 89 of 290