AT91SAM9260: Using 9BIT USART mode with PDC

bole · **Posted:** Mon May 11, 2009 10:22 am

Hi All!

How can I set the 9th bit or detect if 9th bit is set when transferring data through PDC? USART is configured in MODE9.

Thanks

aksignal · **Joined:** Thu Jul 29, 2010 9:23 am **Posts:** 6

Hi,
did you solve it? In Linux?
I just start with this problem, but I think if you set MODE9, the PDC automatically transfer 16 bits.
In user space I use function

Code:

read (port_fd, &a, sizeof (a));

where a is unsigned short. But it some time works and some time doesn't.
Please help me, if you now how.
Thanks

bole · **Posted:** Wed May 16, 2012 2:15 pm

Hi!

Well, my post is 3 years old

I solved the problem, but I will need a day or two to find how.

BlimpyB · **Joined:** Mon Mar 18, 2013 9:43 pm **Posts:** 6

I faced this same problem of MODE9 causing unpredictable results, and this post from 2006 fixed it for me http://www.at91.com/forum/viewtopic.php/f,15/t,1795/hilit,mode9/

On an AT91SAM9x25 with DMAC Rx on a USART in RS485 mode, this seems to do the trick

mode |= ATMEL_US_MODE9 | ATMEL_US_NBSTOP_1 | ATMEL_US_PAR_NONE;

When the parity was enabled, or the stop bit not explicitly set, or ATMEL_US_CHRL_8 turned on, characters would randomly be dropped or shuffled in order, now everything works smoothly.

AT91SAM9260: Using 9BIT USART mode with PDC

Who is online