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Chapter 7
16-Bit Timers
16-Bit Standard PWM Output
(5)
Select fosc as the clock source by the
TM7CK1-0 flag of the TM7MD1 register. Also,
select 1/1 frequency (no division) at count
clock source by the TM7PS1-0 flag.
(6)
Set "H" period of the PWM output to the timer 7
preset register 1 (TM7PR1). To be a 1/4 duty
of the full count (65536), set as follows:
65536 / 4 = 16384 (x'4000')
At that time, the same value is loaded to the
timer 7 compare register 1 (TM7OC1) and the
timer 7 binary counter (TM7BC) is initialized to
x'0000'.
(7)
Set the TM7EN flag of the TM7MD1 register to
"1" to start timer 7.
Setup Procedure
(5)
Select the count clock source.
TM7MD1 (x'3F78')
bp1-0
: TM7CK1-0 = 00
bp3-2
: TM7PS1-0 = 00
(6)
Set "H" period of the PWM output.
TM7PR1 (x'3F75', x'3F74')=x'4000'
(7)
Start the timer operation.
TM7MD1 (x'3F78')
bp4
: TM7EN
= 1
Description
TM7BC counts up from x'0000'. The PWM source waveform outputs "H" until TM7BC reaches the
set value of the TM7OC1 register, then, after the match it outputs "L". After that, TM7BC continues
to count up. Once a overflow occurs, the PWM source waveform outputs "H" again, and TM7BC
counts up from x'0000', again. TM7IO pin outputs one count clock delay of the PWM source wave-
form.
To output the timer pulse output from the TM7O large current pin, set the P5OMD1 flag of the port
5 output mode register (P5OMD) to "1" at the setup example (2), to set the P51 pin as a special
function pin, and set the P5DIR1 flag of the port 5 direction control register to "1" to set output mode.
In the initial state of the PWM output, it is changed to "H" output from "L" output at the timing
that the PWM operation is selected with the TM7OUT1-0 flag of the TM7MD3 register.
As for timer 8, it can be selected with the TM8PWMF flag of TM8MD3.