SH79F1616PSLASH032PR datasheet(39/102 Pages) SINOWEALTH

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SH79F1616

Mode1: Baud-Rate Generator

By set in the T4CON register T4M[1:0] for 01 select timer 4 as baud rate generator. If Timer2 as the baud rate of the serial port

to receive or send, while the timer as another baud rate, the baud rate of the transmit and receive can be different.

The mode is similar to the auto-reload mode. Overflow of Timer4 will causes the Timer4 counter register to be reloaded with the

16-bit value in timer load register. But this will not generate an interrupt.

The baud rates in EUART mode1 and mode3 are determined by Timer4’s overflow rate according to the following equation.

TL4]

[TH4,

65536

/PRESCALER

BaudRate

−

, T4CLKS = 0

TL4]

[TH4,

65536

/PRESCALER

BaudRate

−

, T4CLKS = 1

TH4 and TL4 stand for Timer4 reload register.

Mode2: 16 bit Auto-Reload Timer with T4 Edge Trig

Timer4 in the way for 16-bit auto-reload timer. Bit of T4CON.0 register T4CLKS been 0, Timer 4 can only select the system

clock as the clock source, consistent with the rest of the set with Mode 0.

In Mode2, T4CON.1 the TR4set. Timer4 waiting for T4 trigger signal port (by The T4M [1:0] control the rising/falling) began to

count, a trigger signal to the Timer4 running. When Timer4 overflows from 0xFFFF to 0x0000, TF4 (T4CON.7) will be set and

timer 4 interrupt enable, will produce Timer4 interrupt. T4CLKS bit is always 0. The Timer clock for the system clock. Timer

reload register data re-TH4 and TL4 held until the next trigger signal.

In Mode2, After Setting the TR4 bit (T4CON.1), Timer4 does not start counting but waits the trig signal (rising or falling edge

controlled by T4M[1:0]) from T4. An active trig signal will start the Timer4. When Timer 4 overflows from 0XFFFF to 0x0000, TF4

will be set, TH4 and TL4 will be reloaded from timer load register, and Timer4 holds and waits the next trig edge.

When Timer4 is working, an active trig signal maybe come, if TC bit equals 0, the trig signal will be ignored; if TC bit equals 1,

Timer4 will be re-trigged.

Setting TR4 does not force the timer to reset. The timer register should be loaded with the desired initial value before the timer

is enabled.

TF4

The Block Diagram of Mode 2 of Timer 4

TL4

TH4

Increment Mode

0:Switch Off

1:Switch On

16 bit Counter

Interrupt

Request

Overflow

Flag

TR4

System Clock

Prescaler

1,8,64,256

T4PS[1:0]

control

M2_en

TC4

control

: M2_en set to 1 when T4 edge trig, M2_en set to 0 when counter overflow

Note:

(1) When Timer4 is running (TR4 = 1) as a timer in the baud rate generator mode, TH4 or TL4 should not be written to. Because

a write might overlap a reload and cause write and/or reload errors. So, the timer 4 must be turned off (TR4 = 0) before

accessing the TH4 or TL4 registers.

(2) When Timer4 is used as a counter, the frequency of input signal of T4 pin must be less than half of system clock.

SH79F1616P/032PR Datasheet(PDF) 39 Page - SINOWEALTH Electronic Ltd

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