Baud rate calculation

[Demon]

...Do you really need it as this fast is always my question...

Well, I don't know exactly how fast I need it the USART to go. All I know is that it has to be fast enough so that I can transfer 2 bytes from the 16F to the 18F without losing the USB connection.

I had some difficulty in coming up with a baud rate that was compatible between a 16F @ 20MHz and a 18F @ 48MHz. Since I can't change the FOSC for the 18F because of USB, I did the next best thing and adjusted the FOSC on the 16F. I used 16 MHz which is a multiple of 48, I figured I could come up with a compatible SPBRG value that way.

Sure enough, SPBRG=0 @ 16 MHz and SPBRG=2 @ 48 MHz both give 1000 KBAUD. It's not the maximum of 1250, but it's close. Now I have to make some tests later and see if the USB connection holds up.

Robert

[mister_e]

use the calc and get the lower error % is one of the best trick i can say. Now uncheck the BRGH=1 box to compare both results. Sometime BRGH=1 give a better error % sometimes not. it's all depend of the OSC speed and the BRGH setting. This one of the reason i did this calc. Probably i could add an auto error % feature wich will compare both BRGH=1 and BRGH=0 results and give the best of it. As now it just provide the best error % for the BRGH you choose.

Using your example, both gave 0% error percentage.. couldn't be better assuming a real 16MHZ and a real 48MHZ
HTH

[Demon]

Thanks Steve, the new "improved" version works great!

Robert

[mister_e]

How dare you edit the title bar? mon esti'd'chien sale LMAO!

Great to know it's working

[Demon]

Paint Brush is my friend.

I was wondering if you'd notice.

Robert

[mister_e]

Hehe... yes i do