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Re: [avr-gcc-list] Butterfly RS232?

From: Mike Young
Subject: Re: [avr-gcc-list] Butterfly RS232?
Date: Tue, 29 Nov 2005 18:24:36 -0600

Thanks. The pin is completely dead when I probe it with a scope. It can hardly be hardware in this day and age. Right?

The gcc-port code looks as follows. Connection settings on the PC are 19200, 8N1, no handshake. Receive works just fine, else I wouldn't be bothering you with it. I know for certain the code gets to the _Tx function when it should. It hits breakpoints in the debugger, and I've added that annoying PlayClick in the callers.

void USART_Init(unsigned int baudrate)


   // Set baud rate

   UBRRH = (unsigned char)(baudrate>>8);

   UBRRL = (unsigned char)baudrate;

   // Enable 2x speed

   UCSRA = (1<<U2X);

   // Enable receiver

   UCSRB = (1<<RXEN)|(0<<TXEN)|(0<<RXCIE)|(0<<UDRIE);

   // Async. mode, 8N1

   UCSRC = (0<<UMSEL)|(0<<UPM0)|(0<<USBS)|(3<<UCSZ0)|(0<<UCPOL);


void Usart_Tx(char data)


   while (!(UCSRA & (1<<UDRE)));

   UDR = data;


char Usart_Rx(void)


   while (!(UCSRA & (1<<RXC)));

   return UDR;


----- Original Message ----- From: "Steve Franks" <address@hidden>
To: "'Mike Young'" <address@hidden>
Sent: Tuesday, November 29, 2005 5:50 PM
Subject: RE: [avr-gcc-list] Butterfly RS232?


I've done it, seems to work fine for me. Hooked up DB9 directly to the pins
on the butterfly.  Will try to remember to send code when home this eve.


-----Original Message-----
From: Mike Young [mailto:address@hidden
Sent: Tuesday, November 29, 2005 1:15 PM
To: address@hidden
Subject: [avr-gcc-list] Butterfly RS232?

Looking at the schematic for the Butterfly, it's not readily
apparent how it
manages to translate levels for outbound data. The docs seem
to say it's
supposed to work, but my primitive understanding of
electronics matches the
results: non-receipt of "transmitted" data. It could also be
my primitive
understanding of the mega169's usart that's at fault. Is the
ported gcc
Butterfly usart code supposed to work?

Many thanks.

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