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POAVR Butterfly UART - can't receive data
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  1. POAVR Butterfly UART - can't receive data
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    copied!<p>I am using the UART of Atmega169/AVR Butterfly for transmission to another board, baudrate 56700, no parity, 1 stopbit, no flow control. The oscillator is running at 7,3768Mhz (checked). I can transmit data successfully (checked with the other board and PC/HyperTerminal), but not receive any data - when running the debugger the configuration bits are all set correctly, but RXC is false constantly - I also checked if I can send data to myself (connected TXD to RXD and grounded), but without success. (Tried with ISR as well as polling) Below are the relevant parts of the code, I hope you can deal with it - PORTB is used as output for testing with the oscilloscope (I know I could just use one pin, but there is nothing else on PORTB right now):</p> <pre><code>int main(void){ OSCCAL_Calibrate(); // calibrate the internal oscillator int UBRR_VAL = ((F_CPU)/(BAUD*16)-1); UART_Init(UBRR_VAL); DDRB |= 0xFF; PORTB = 0; testCharSend(); while(1); return 0; } void testCharSend() { char i = 'x'; while(1){ Uart_Tx(i); } } void UART_Init(unsigned int baudrate) { // Set baud rate UBRRH = (unsigned char)(baudrate&gt;&gt;8); UBRRL = (unsigned char)baudrate; UCSRA = 0; // Enable receiver and transmitter UCSRB = (1&lt;&lt;RXEN)|(1&lt;&lt;TXEN); // Async. mode, 8bit, No parity, 1 stop bit (like CC2540) UCSRC = (0&lt;&lt;UMSEL)|(0&lt;&lt;UPM0)|(0&lt;&lt;USBS)|(3&lt;&lt;UCSZ0)|(0&lt;&lt;UCPOL); // enable receive interrupt UCSRB |= (1&lt;&lt;RXCIE); // flush UART UART_Flush(); } void UART_Flush( void ) { unsigned char dummy; while ( UCSRA &amp; (1&lt;&lt;RXC) ) dummy = UDR; } void Uart_Tx(char data) { while (!(UCSRA &amp; (1&lt;&lt;UDRE))); UDR = data; } ISR (USART0_RX_vect) { PORTB ^= 0xFF; char c = UDR; } </code></pre>
 

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