Re: [avr-gcc-list] UART transmitting problem

[Russell Shaw]

Laurence Anderson wrote:
> Hi Guys,
>
> I've updated the program, and used the latest winavr distro, and its still see 
> nothing in hyperterminal. Just to give more background, I have receiving 
> working fine. Also the origional code seems to transmit ok, so I gradually 
> removed parts of the code & re-tested, gradually it got more unreliable (only 
> sending a message every 3 times it was turned on), then just sent one space 
> instead of the message, until it did nothing, and this was just by removing 
> code not relevant to transmitting! In one case removing an unsued global int 
> stopped it working! What could cause something like this?
>
> Thanks for all the help,
>
> Laurence
>
> #include <avr/io.h>
>
> char *message = "Testing, testing, 1-2-3";
>
> int main()
> {
>         char c, *buf = message;
>
>         // Enable transmitting, 9600bps (clock is 4Mhz)
>         UCR = _BV(TXEN);
>         UBRR = 25;
>
>         while ( ( c = *buf++ ) != '\0' ) {
>                 UDR = c;
>                 loop_until_bit_is_set( USR, UDRE );
>         }
>
>         return 0;
> }

Can't remember if this is needed, but have you set the TXD pin
as an output? What does a CRO show?