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Re: [avr-gcc-list] Small program for UART not working
From: |
Vincent Trouilliez |
Subject: |
Re: [avr-gcc-list] Small program for UART not working |
Date: |
Mon, 12 Sep 2005 21:23:44 +0200 |
> >Send 0xAA continiously. That way you get a nice
> >square wave at the baud rate frequency. If you drop
>
> I thought it was 0x55 (or ASCII 'U') that you wanted, rather than 0xAA.
>
> An idle RS-232 line is in the "Mark" state. Start bit is "Mark" to "Space"
> transition. Data bits are then sent LSB first, with "Mark" == 1, "Space" ==
> 0, so the LSB has to be a '1'. After the last databit (bit 7 is zero, or
> "Space"), the stop bit puts the line back into idle ("Mark") for 1 bit time.
>
> This should work for 8N1.
>
> Regards,
> -=Dave
Indeed, when I started playing with my AVR's UART a few days ago and
sent an 0xAA, the frame looked weird on the scope, at first I thought I
got the frame format wrong, 5 data bit instead of 8 or something ! ;-)
0x55 would probably have looked much better indeed...
--
Vince