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occurred Oct 21, 2018 at 0:00

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edited Oct 20, 2018 at 10:16

I'm using an ATMEGA328p, running from its internal oscillator (divided by 8 = 1MHz).

I've (roughly) measured the oscillator output, using my Salae logic analyser, as ranging from 960KHz to 1000KHz, so it's not awful. I did this using the "Clock output on PORTB0" fuse.

If I set the baud rate to 9,600, it outputs serial at 10,220 baud. (BecauseIs this because I'm not using a crystal, or because of quantisation?)

If I either increase F_CPU or decrease USART_BAUDRATE, gradually, the output serial baud does not decrease, until it jumps to 8,800 baud.

#define USART_BAUDRATE 9600 #define BAUD_PRESCALE (((F_CPU / (USART_BAUDRATE * 16UL))) - 1) int main(void) { // serial port setup UCSR0B |= (1 << RXEN0) | (1 << TXEN0); UCSR0C |= (1 << UCSZ00) | (1 << UCSZ01); UBRR0H = (BAUD_PRESCALE >> 8); UBRR0L = BAUD_PRESCALE; ...

Is there some form of quantisation affecting the output baud?

P.S. I'm using GCC on Linux to compile code, and I'm not using Arduino code/IDE.

I'm using an ATMEGA328p, running from its internal oscillator (divided by 8 = 1MHz).

I've (roughly) measured the oscillator output, using my Salae logic analyser, as ranging from 960KHz to 1000KHz, so it's not awful. I did this using the "Clock output on PORTB0" fuse.

If I set the baud rate to 9,600, it outputs serial at 10,220 baud. (Because I'm not using a crystal, or because of quantisation?)

If I either increase F_CPU or decrease USART_BAUDRATE, gradually, the output serial baud does not decrease, until it jumps to 8,800 baud.

#define USART_BAUDRATE 9600 #define BAUD_PRESCALE (((F_CPU / (USART_BAUDRATE * 16UL))) - 1) int main(void) { // serial port setup UCSR0B |= (1 << RXEN0) | (1 << TXEN0); UCSR0C |= (1 << UCSZ00) | (1 << UCSZ01); UBRR0H = (BAUD_PRESCALE >> 8); UBRR0L = BAUD_PRESCALE; ...

Is there some form of quantisation affecting the output baud?

P.S. I'm using GCC on Linux to compile code, and I'm not using Arduino code/IDE.

I'm using an ATMEGA328p, running from its internal oscillator (divided by 8 = 1MHz).

I've (roughly) measured the oscillator output, using my Salae logic analyser, as ranging from 960KHz to 1000KHz, so it's not awful. I did this using the "Clock output on PORTB0" fuse.

If I set the baud rate to 9,600, it outputs serial at 10,220 baud. (Is this because I'm not using a crystal, or because of quantisation?)

If I either increase F_CPU or decrease USART_BAUDRATE, gradually, the output serial baud does not decrease, until it jumps to 8,800 baud.

#define USART_BAUDRATE 9600 #define BAUD_PRESCALE (((F_CPU / (USART_BAUDRATE * 16UL))) - 1) int main(void) { // serial port setup UCSR0B |= (1 << RXEN0) | (1 << TXEN0); UCSR0C |= (1 << UCSZ00) | (1 << UCSZ01); UBRR0H = (BAUD_PRESCALE >> 8); UBRR0L = BAUD_PRESCALE; ...

Is there some form of quantisation affecting the output baud?

P.S. I'm using GCC on Linux to compile code, and I'm not using Arduino code/IDE.

edited tags

Source Link

edited Oct 20, 2018 at 10:08

fadedbee

I'm using an ATMEGA328p, running from its internal oscillator (divided by 8 = 1MHz).

I've (roughly) measured the oscillator output, using my Salae logic analyser, as ranging from 960KHz to 1000KHz, so it's not awful. I did this using the "Clock output on PORTB0" fuse.

If I set the baud rate to 9,600, it outputs serial at 10,220 baud, because. (Because I'm not using a crystal., or because of quantisation?)

If I either increase F_CPU or decrease USART_BAUDRATE, gradually, the output serial baud does not decrease, until it jumps to 8,800 baud.

#define USART_BAUDRATE 9600 #define BAUD_PRESCALE (((F_CPU / (USART_BAUDRATE * 16UL))) - 1) int main(void) { // serial port setup UCSR0B |= (1 << RXEN0) | (1 << TXEN0); UCSR0C |= (1 << UCSZ00) | (1 << UCSZ01); UBRR0H = (BAUD_PRESCALE >> 8); UBRR0L = BAUD_PRESCALE; ...

Is there some form of quantisation affecting the output baud?

P.S. I'm using GCC on Linux to compile code, and I'm not using Arduino code/IDE.

I'm using an ATMEGA328p, running from its internal oscillator (divided by 8 = 1MHz).

I've (roughly) measured the oscillator output, using my Salae logic analyser, as ranging from 960KHz to 1000KHz, so it's not awful. I did this using the "Clock output on PORTB0" fuse.

If I set the baud rate to 9,600, it outputs serial at 10,220 baud, because I'm not using a crystal.

If I either increase F_CPU or decrease USART_BAUDRATE, gradually, the output serial baud does not decrease, until it jumps to 8,800 baud.

#define USART_BAUDRATE 9600 #define BAUD_PRESCALE (((F_CPU / (USART_BAUDRATE * 16UL))) - 1) int main(void) { // serial port setup UCSR0B |= (1 << RXEN0) | (1 << TXEN0); UCSR0C |= (1 << UCSZ00) | (1 << UCSZ01); UBRR0H = (BAUD_PRESCALE >> 8); UBRR0L = BAUD_PRESCALE; ...

Is there some form of quantisation affecting the output baud?

P.S. I'm using GCC on Linux to compile code, and I'm not using Arduino code/IDE.

I'm using an ATMEGA328p, running from its internal oscillator (divided by 8 = 1MHz).

I've (roughly) measured the oscillator output, using my Salae logic analyser, as ranging from 960KHz to 1000KHz, so it's not awful. I did this using the "Clock output on PORTB0" fuse.

If I set the baud rate to 9,600, it outputs serial at 10,220 baud. (Because I'm not using a crystal, or because of quantisation?)

If I either increase F_CPU or decrease USART_BAUDRATE, gradually, the output serial baud does not decrease, until it jumps to 8,800 baud.

#define USART_BAUDRATE 9600 #define BAUD_PRESCALE (((F_CPU / (USART_BAUDRATE * 16UL))) - 1) int main(void) { // serial port setup UCSR0B |= (1 << RXEN0) | (1 << TXEN0); UCSR0C |= (1 << UCSZ00) | (1 << UCSZ01); UBRR0H = (BAUD_PRESCALE >> 8); UBRR0L = BAUD_PRESCALE; ...

Is there some form of quantisation affecting the output baud?

P.S. I'm using GCC on Linux to compile code, and I'm not using Arduino code/IDE.

edited tags

Source Link

edited Oct 20, 2018 at 10:03

fadedbee

Are an Is the ATMEGA328P's serial baud ratesrate quantised?

I'm using an ATMEGA328p, running from its internal oscillator (divided by 8 = 1MHz).

I've (roughly) measured the oscillator output, using my Salae logic analyser, as ranging from 960KHz to 1000KHz, so it's not awful. I did this using the "Clock output on PORTB0" fuse.

If I set the baud rate to 9,600, it outputs serial at 10,220 baud, because I'm not using a crystal.

If I either increase F_CPU or decrease USART_BAUDRATE, gradually, the output serial baud does not decrease, until it jumps to 8,800 baud.

#define USART_BAUDRATE 9600 #define BAUD_PRESCALE (((F_CPU / (USART_BAUDRATE * 16UL))) - 1) int main(void) { // serial port setup UCSR0B |= (1 << RXEN0) | (1 << TXEN0); UCSR0C |= (1 << UCSZ00) | (1 << UCSZ01); UBRR0H = (BAUD_PRESCALE >> 8); UBRR0L = BAUD_PRESCALE; ...

Is there some form of quantisation affecting the output baud?

(P P.S. I'm using GCC on Linux to compile code, and I'm not using Arduino code/IDE.)

Are an ATMEGA328P's serial baud rates quantised?

I'm using an ATMEGA328p, running from its internal oscillator.

If I set the baud rate to 9,600, it outputs serial at 10,220 baud, because I'm not using a crystal.

If I either increase F_CPU or decrease USART_BAUDRATE, gradually, the output serial baud does not decrease, until it jumps to 8,800 baud.

#define USART_BAUDRATE 9600 #define BAUD_PRESCALE (((F_CPU / (USART_BAUDRATE * 16UL))) - 1) int main(void) { // serial port setup UCSR0B |= (1 << RXEN0) | (1 << TXEN0); UCSR0C |= (1 << UCSZ00) | (1 << UCSZ01); UBRR0H = (BAUD_PRESCALE >> 8); UBRR0L = BAUD_PRESCALE; ...

Is there some form of quantisation affecting the output baud?

(P.S. I'm using GCC on Linux to compile code, and I'm not using Arduino code/IDE.)

Is the ATMEGA328P's serial baud rate quantised?

I'm using an ATMEGA328p, running from its internal oscillator (divided by 8 = 1MHz).

I've (roughly) measured the oscillator output, using my Salae logic analyser, as ranging from 960KHz to 1000KHz, so it's not awful. I did this using the "Clock output on PORTB0" fuse.

If I set the baud rate to 9,600, it outputs serial at 10,220 baud, because I'm not using a crystal.

If I either increase F_CPU or decrease USART_BAUDRATE, gradually, the output serial baud does not decrease, until it jumps to 8,800 baud.

#define USART_BAUDRATE 9600 #define BAUD_PRESCALE (((F_CPU / (USART_BAUDRATE * 16UL))) - 1) int main(void) { // serial port setup UCSR0B |= (1 << RXEN0) | (1 << TXEN0); UCSR0C |= (1 << UCSZ00) | (1 << UCSZ01); UBRR0H = (BAUD_PRESCALE >> 8); UBRR0L = BAUD_PRESCALE; ...

Is there some form of quantisation affecting the output baud?

P.S. I'm using GCC on Linux to compile code, and I'm not using Arduino code/IDE.

Source Link

asked Oct 20, 2018 at 9:54

fadedbee