SH79F3283PSLASH044PR datasheet(97/144 Pages) SINOWEALTH

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SH79F3283

8.5.3 EUART1

The control and operate mode of EUART1 is similar to EUART0, the different is EUART1 has a baud rate generator is an

15-bit up-counting timer.

Otherwise, the baud rate generator of EURART1 has baud rate fine adjustment function by set BFINE register.

15-bit timer

EUART1

Overflow

Fsys

From 7FFFH to

0000H

SBRTH[14:8], SBRTL7:0]

Baudrate Generator for EUART

SBRTEN=1

SBRT

32768

Fsys

owrate

SBRToverfl

−

，

]

[

SBRTL

SBRTH

SBRT

So that, the baud rate computational formula of EUART1 in different modes as shown below.

Mode0:

In Mode0, the baud rate is programmable to either 1/12 or 1/4 of the system frequency. This baud rate is determined by SM2

bit. When set to 0, the serial port runs at 1/12 of the system clock. When set to 1, the serial port runs at 1/4 of the system clock.

Mode1 and Mode3:

In Mode1 & Mode3, the baud rate can be fine adjusted.

The Mode1 & 3 baud rate equations are shown below,

(

) BFINE

SBRT

BaudRate

32768

sys

For example: Fsys = 8MHz, to get 115200Hz baud rate, computing method of SBRT and SFINE as shown below:

8000000/16/115200 = 4.34

SBRT = 32768 - 4 = 32764

115200 = 8000000/(16 X 4 + BFINE)

BFINE = 5.4 ≈ 5

This fine tuning method to calculate the actual baud rate is 115942Hz and the error is 0.64%, but the error is 8.5% In the past

computing method.

Mode2:

In Mode2, the baud rate is programmable to either 1/32 or 1/64 of the system clock. This baud rate is determined by the

SMOD bit (PCON.7). When this bit is set to 0, the serial port runs at 1/64 of the clock. When set to 1, the serial port runs at

1/32 of the clock.

)

(

SYS

SMOD

BaudRate

Note: TF3 cleared by hardware, and the interrupt vector address is as the same as Uart1. Please pay attention to the interrupt

flag, when use both Timer3 and Uart1.

SH79F3283P/044PR Datasheet(PDF) 97 Page - SINOWEALTH Electronic Ltd

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