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Topic: Extra characters in UART (Read 676 times) previous topic - next topic



I am getting extra characters at the end of a string I am sending via UART to my PC. I am sending the string "North: 0x" and I get the following output (as seen in Hyperterminal):
N   o  r   t   h   :       0   x %(without the spaces and % representing the extra characters)
4E 6F 72 74 68 3A 20 30 78 0F 00 00 00 0D 0A (hexadecimal representation)
with the extra characters being the 0x0F 0x00 0x00 0x00.

My code extract is as follows:
Code: [Select]

   ; print "North :"
   ldi r31, HIGH(2*north_txt)
   ldi r30, LOW(2*north_txt)
   rcall print_string


   ; baud rate passed via registers r17(H) and r16(L)
   sts UBRR0H, r17
   sts UBRR0L, r16
   ; enable Tx and RX
   ldi r16, (1 << RXEN0 | 1 << TXEN0)
   sts UCSR0B, r16
   ; frame format - 8bits, no parity, 1 stop bit
   ldi r16, (1 << UCSZ01 | 1 << UCSZ00)
   sts UCSR0C, r16


; data to be transmitted must be loaded into
; register r16
   lds r17, UCSR0A
   sbrs r17, UDRE0
   rjmp print_char
   sts UDR0, r16

   lpm r16, Z+
   ; check for end of string
   cpi r16, 0x00
   breq eof
   rcall print_char
   ; next character
   rjmp print_string

north_txt: .db "North: 0x", 0x00

I am using AVR Studio 4 on a Windows XP SP3 to program the Atmega328P on an Arduino Duemilanove.

Has anybody had the same problem and how do I resolve it?

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