Change Baudrate of UART in Application

wolf2 · ‎2006-06-19

Posted on June 20, 2006 at 04:14

wolf2 · ‎2006-06-15

Posted on June 15, 2006 at 14:26

Dear RISC:

I develop an application.

9600 is the default of both Host and Client.

Host sends command let Client changes to 115200.

Client uses 9600 respone ACK to Host. Wait TXEmpty on , Client changes to 115200.

Question:

What is the flow which changes from 9600 to 115200 ?

How many time is need to wait ?

Because:

I set a breakpoint at TXEmpty , Stop and Run. It is OK.

If no breakpoint , Host needs to retry 2 or 3 times.

Thank you.

wolf2 · ‎2006-06-19

Posted on June 20, 2006 at 04:14

Thank you.

Because our project is so huge.

We are follow the ModBus like Protocol.

ex:

We define :

0 : 9600(default)

1 : 19200

2 : 38400

3 : 57600

4 : 115200

function code : 0x32

PC -> :013204xx (9600)

ST -> :013204xx (echo 9600 ok)

I wait TXEmpty launched.

Change Baudrate to 115200.(PC & ST)

Both PC & ST delay 1 second

PC -> :0103xxxx... (115200 request,it will timeout one or two times)

After retry one or two times, ST responds correctly.

I want to know what I need to do, when I pre-change or post-change baudrate ?

Like Stop RX or.......

Thank you.