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CHAPTER 7 8-BIT PWM TIMER
Table 7.4-1 Explanation of the Functions of Each Bit in the PWM Control Register (CNTR)
Bit name Function
bit7
P/TX:
Bit to select the
operation mode
This bit is used to select the interval timer operation (P/TX = 0) or PWM timer
operation (P/TX = 1).
Note:
Before writing into this bit, stop the counter operation (TPE = 0), disable an
interrupt (TIE = 0), and clear the interrupt request flag bit (TIR = 0).
bit6 Unused bit
The value during a read is undetermined.
A write does not affect operations.
bit5,
bit4
P1, P0:
Bits to select the clock
This bit is used to select the count clock of the interval timer functions or PWM
timer functions.
One of three types of internal count clock or the output of the 8/16-bit capture
timer or counter can be selected.
Note:
When the counter is operating (TPE = 1), do not switch P1 and P0.
bit3
TPE:
Bit to enable the counter
operation
This bit is used to start and stop the interval timer functions or PWM timer
functions.
To start the count operation, write "1" to this bit. When "0" is written to this bit,
the counter is cleared (setting 00
H
) and then stopped.
bit2
TIR:
Interrupt request flag bit
While the internal timer functions are enabled:
When the counter value matches the PWM compare register (COMR) value, "1" is
set to this bit.
When this bit and the bit to enable an interrupt request (TIE) are "1", an interrupt
request to the CPU is output.
While the PWM timer functions are enabled, an interrupt request does not occur.
When this bit is written, it is cleared (setting "0"). Writing "1" does not affect this
bit in any way.
bit1
OE:
Bit to control the output
pin
When this bit is "0", the P50/PWM pin is used as a general-purpose port (P50).
When the bit is "1", it is used as a dedicated pin (PWM).
When the interval timer functions are enabled, the square wave is output to the
PWM pin. When the PWM timer functions are enabled, the PWM wave is output
to the PWM pin.
bit0
TIE:
Bit to enable an interrupt
request
This bit is used to enable and disable the output of an interrupt request to the CPU.
When this bit and the interrupt request flag bit (TIR) are both "1", an interrupt
request is output.