relationship between baudrates and performance

Hello everyone
I'm not sure this is right place to ask, anyway this is my question
I use HC-06 bluetooth module
I claculate the sizes of sent datas and its 6204bytes per 1sec
then baudrates I should use maybe 57600.

But if I set baudrates to 115200, there will be a problem?
and if I set bigger baudrates, then microcontroller's performance go to low?
why baudrates are 9600 to 115200?
if baudrates is not influenced to microcontroller's performance, faster will be always good right?
why setting baudrates is important?

I'm not good an English so my writing maybe awkward. Please understand
but if you know the answer, help me :slight_smile:

Depending on the type of connection, high serial baud rates can lead to communication errors.

So, you usually want to use the fastest baud rate that does not lead to problems.

The bit rate for an AVR UART is not a perfect match for many of the standard rates. For example at 115200 there is a large timing error that can end up causing a framing error. In my experiments, the 115200 bit rate on a 16MHz AVR worked fine when I had some dead time between characters, but when I crowded characters one after the next the framing errors started to show up. There are non-standard bit rates (e.g. 125000 and 250000) that have zero timing error on a 16MHz AVR so I have started to use them for some things. For the task that requires standard bit rates, I use 38400 (76800 is also an option at 16MHz, but I wanted it to work with a 12MHz AVR and 76.8k is not very standard).

Here is an AVR baud rate calculator:
http://wormfood.net/avrbaudcalc.php

jremington:
Depending on the type of connection, high serial baud rates can lead to communication errors.

So, you usually want to use the fastest baud rate that does not lead to problems.

oh.. I have one more question
I calculate the size of datas sent via bluetooth
and it was 8604 bytes per second. then choose 115200 baud rates is an appropriate option. right?

ron_sutherland:
The bit rate for an AVR UART is not a perfect match for many of the standard rates. For example at 115200 there is a large timing error that can end up causing a framing error. In my experiments, the 115200 bit rate on a 16MHz AVR worked fine when I had some dead time between characters, but when I crowded characters one after the next the framing errors started to show up. There are non-standard bit rates (e.g. 125000 and 250000) that have zero timing error on a 16MHz AVR so I have started to use them for some things. For the task that requires standard bit rates, I use 38400 (76800 is also an option at 16MHz, but I wanted it to work with a 12MHz AVR and 76.8k is not very standard).

Here is an AVR baud rate calculator:
WormFood's AVR Baud Rate Calculator Ver. 2.0.0

wow its really hard to see!
I use odroid xu4 to receive these datats
and like i quote above I sent 8604 bytes per second
and I think that there are just standard baudrates options on HC-06 to choose

I would think the HC-06 serial pass through has a good baud rate clock, so it should have very low timing error with your Ordroid SBC. However, an AVR at 16MHz may have over 2% timing error with the HC-06 and that is the sort of thing I was running into framing errors with (between an FTDI chip and the AVR).

ron_sutherland:
I would think the HC-06 serial pass through has a good baud rate clock, so it should have very low timing error with your Ordroid SBC. However, an AVR at 16MHz may have over 2% timing error with the HC-06 and that is the sort of thing I was running into framing errors with (between an FTDI chip and the AVR).

thanks for your advice!
and I've already post at arduino101 but if you know this answer or help me
please help me

I try to use arduino101 to communicate with odroid
(I use three arduinos and odroid...lol)
I'm not familiar with arduino 101 and which baudrates will be the best to arduino 101 do you think?
I dont want to meet the timing error

That is one thing the Intel board should do well with, its UART should be fine at standard baud rates.

ron_sutherland:
That is one thing the Intel board should do well with, its UART should be fine at standard baud rates.

thx!!! u really help me a lot!
then I will set baudrates of 101 board to 57600 then
again, thanks for your kind answers!