M32C80 Datasheet, PDF (163/352 Pages) Renesas Technology Corp – 16/32-BIT SINGLE-CHIP MICROCOMPUTER M16C FAMILY / M32C/80 SERIES

M32C/80 Group
14. Timer (Timer A)
14.1.4 Pulse Width Modulation Mode
In pulse width modulation mode, the timer outputs pulse of desired width continuously (see Table 14.7).
The timer counter functions as either 16-bit pulse width modulator or 8-bit pulse width modulator. Figure
14.13 shows the TAiMR register (i=0 to 4) in pulse width modulation mode. Figures 14.14 and 14.15
show examples of how a 16-bit pulse width modulator operates and of how an 8-bit pulse width modulator
operates.
Table 14.7 Pulse Width Modulation Mode Specifications
Item
Specification
Count Source
f1, f8, f2n(1), fC32
Counting Operation
• The timer decrements a counter value
(The counter functions as an 8-bit or a 16-bit pulse width modulator)
Content of the reload register is reloaded on the rising edge of PWM pulse and count-
ing continues.
The timer is not affected by a trigger that is generated during counting.
16-Bit PWM
• "H" width = n / fj
n : setting value of the TAi register 000016 to FFFE16
fj : count source frequency
• Cycle = (2¹⁶-1) / fj fixed
8-Bit PWM
• "H" width = n x (m+1) / fj
• Cycles = (2⁸-1) x (m+1) / fj
m : setting value of low-order bit address of the TAi register 0016 to FF16
n : setting value of high-order bit address of the TAi register 0016 to FE16
Counter Start Condition
• External trigger input is provided
• Timer counter overflows or underflows
• The TAiS bit in the TABSR register is set to "1" (starts counting)
Counter Stop Condition
The TAiS bit is set to "0" (stops counting)
Interrupt Request Generation Timing On the falling edge of the PWM pulse
TAiIN Pin Function
Programmable I/O port or trigger input
TAiOUT Pin Function
Pulse output
Read from Timer
The value in the TAi register is indeterminate when read
Write to Timer
• When the timer counter stops, the value written to the TAi register is also written to
both reload register and counter
• While counting, the value written to the TAi register is written to the reload register
(It is transferred to the counter at the next reload timing)
NOTE:
1. The CNT3 to CNT0 bits in the TCSPR register select no division (n=0) or divide-by-2n (n=1 to 15).
Rev. 1.00 Nov. 01, 2005 Page 144 of 330
REJ09B0271-0100