Atmega16 serial port baud rate setting problem

woshiyulei

Atmega16 serial port baud rate setting problem [Copy link]

I just learned AVR. According to the tutorial, I set the serial port baud rate to 9600. However, when debugging with the serial port, the baud rate must be 600 to output normally. Why is it not 9600? The code is as follows: #include
#include
#include

#define F_CPU 16000000 #define BAUD 9600 int main(void) { unsigned char temp = 0x55; DDRB = 0xff; PORTB = 0xaa; UBRRH = ( F_CPU/BAUD/16 - 1 ) / 256; /*Set baud rate*/ UBRRL = ( F_CPU/BAUD/16 - 1 ) % 256; UCSRB |= ( 1 << RXEN ) | ( 1 << TXEN ) | ( 1 << RXCIE ); /*Receive enable, transmit enable, receive end interrupt enable*/ sei(); /*Enable global interrupt*/ while(1) { while( !( UCSRA & ( 1 << UDRE ) ) ); temp = ~temp; UDR = temp; PORTB = ~PORTB; _delay_ms( 1000 ); } return 0; } Please give me some advice, thank you

ddlxiaoxu

Is it about the crystal? At the beginning of AVR, it seems that the internal 1M RC oscillator is usually selected. If the crystal oscillator is selected externally, the fuse position is adjusted.

gh131413

Modify the fuse position, select the external crystal oscillator, and see if the voltage supports 16M. If not, change to an 8M external crystal oscillator. At the same time, the software should also be modified to match the crystal oscillator frequency.

hnjylijunz

I think the problem is in your fuse position. The baud rate you use is 9600, but it is actually 600. 9600/600=16. The difference is 16 times. The crystal oscillator you use is 16M, and the internal RC oscillator is 1M, which is exactly 16 times different. This should not be a coincidence, right? Think about it? ::loveliness: