Page 1 of 1

How to change baud rate to 9600 on AN-8 demo?

PostPosted: Wed Sep 14, 2005 7:38 am
by aek
Hello noom.

The PIC doesn't have enough processing power to run multiple 9600 baud software UARTs using the code in AN-8 ...

Using AN-8, you can run 4 software UARTs at 1200 baud. You may also be able to run 2 software UARTs at 2400 baud and 1 software UART at 4800 baud. I doubt you can run any 9600 baud software UARTs using the task-based approach in AN-8.

Bit-banging multiple 9600 baud transmit-only UARTs is pretty easy. But doing multiple receivers -- and perhaps more importantly, having enough cycles to run the rest of your application -- is considerably more complex.

The point of AN-8 is to demonstrate that you can build an application that has 4 1200 baud software UARTs and can also run additional tasks simply by creating the additional tasks at lower priorities than the software UART tasks. IOW, it's easily extended to a bigger application.

------------------


Re: How to change baud rate to 9600 on AN-8 demo?

PostPosted: Wed Sep 14, 2005 7:42 am
by aek
quote:
I try to change baud rate to 9600 but the max baud rate I can get only 2400
As per AN-8, it takes a 20MHz PIC to run 4 software UARTs at 1200 baud.

So it's completely understandable that a 40MHz PIC can do 4 software UARTs at 2400 baud, but not faster.

------------------


Re: How to change baud rate to 9600 on AN-8 demo?

PostPosted: Wed Sep 14, 2005 11:21 am
by noom
I try to change baud rate to 9600 but the max baud rate I can get only 2400. I used PIC18F252 with XTAL 10MHz PLL to 40MHz