Panasonic MN101C77C, F77G user manual TM4EN, TM4PWM, TM4MOD, TM4BAS

Chapter 6 8-bit Timers

6-8-2 Setup Example

„Serial Interface Transfer Clock Setup Example (Timer 4)

How to create a transfer clock for half duplex UART (Serial interface 1) using with timer 4 is shown below. The baud rate is selected to be 300 bps, the source clock of timer 4 is selected to be fs/4 (at fosc=8 MHz).

An example setup procedure, with a description of each step is shown below.

	Setup Procedure					Description
(1)	Stop the counter.			(1)	Set the TM4EN flag of the timer 4 mode
	TM4MD (x'3F64')				register (TM4MD) to "0" to stop timer 4
	bp3	:TM4EN	= 0		counting.
(2)	Select the normal timer operation.			(2)	Set the TM4PWM flag and TM4MOD flag of
	TM4MD (x'3F64')				the TM4MD register to "0" to select the normal
	bp4	:TM4PWM	= 0		timer operation.
	bp5	:TM4MOD	= 0
(3)	Select the count clock source.			(3)	Select the clock source to prescaler output by
	TM4MD (x'3F64')				the TM4CK2-0 flag of the TM4MD register.
	bp2-0	:TM4CK2-0 = 001
(4)	Select the prescaler output and			(4)	Select the prescaler output to fs/4 by the
	enable counting.				TM4PSC1-0, TM4BAS flag of the timer 4
	CK4MD (x'3F66')				prescaler selection register (CK4MD).
	bp2-1	:TM4PSC1-0 = 01			Also, set the PSCEN flag of the prescaler
	bp0	:TM4BAS	= 1		control register (PSCMD) to "1" to enable the
	PSCMD (x'3F6F')				prescaler counting.
	bp0	:PSCEN	= 1
(5)	Set the baud rate.			(5)	Set the timer 4 compare register (TM4OC) to
	TM4OC (x'3F62')		= x'CF'		the value that baud rate comes to 300 bps.
					[	Chapter 12. Table 12-3-19 ]
					At that time, the timer 4 binary counter
					(TM4BC) is initialized to x'00'.
(6)	Start the timer operation			(6)	Set the TM4EN flag of the TM4MD register to
	TM4MD (x'3F64')				"1" to start timer 4.
	bp3	:TM4EN	= 1

VI - 34 Serial Transfer Clock Output