16F18446 - setting baudrate for HW EUSART

[richard]

when you get a result like
DEFINE HSER_SPBRG 832 you realize something is very wrong since an 8 bit register can not accept that value ever

you have enabled the 16 bit baud rate generator in every case


BAUDCON.3 = 1 'Enable 16 bit baudrate generator

for 19200
SP1BRGL = 160:SP1BRGH = 1

for 9600
SP1BRGL = 64:SP1BRGH = 3


BAUDCON.3 = 0 '8 bit baudrate generator
for 9600
SP1BRGH = 51

for 19200
SP1BRGH = 25

[richard]

its probably better to say

there are two baudrate clock source dividers brgh=0 ; fosc/64 and brgh=1 ; fosc/16 and
and you have the choice of 8 or 16 bit baud rate generators, so 4 options for every baud rate


BAUDCON.3 = 1 'Enable 16 bit baudrate generator
brgh=1
for 19200
SP1BRGL = 160:SP1BRGH = 1

for 9600
SP1BRGL = 64:SP1BRGH = 3

brgh=0
for 19200
SP1BRGL = 103:SP1BRGH =0


for 9600
SP1BRGL = 207:SP1BRGH = 0





BAUDCON.3 = 0 '8 bit baudrate generator
brgh=1
for 9600
SP1BRG = 207


for 19200
SP1BRG = 103

brgh=0
for 9600
SP1BRG = 51

for 19200
SP1BRG = 25

[flotulopex]

Thanks a lot Richard.

All your settings work like a charm

Still a question: why would one choose the 8 bit baudrate generator - seems less accurate, no?

[richard]

why would one choose the 8 bit baudrate generator - seems less accurate, no?

in reality accuracy is not always critically important, 1% or larger errors still work well in 90% of cases for tty serial transmission.
8bit generator results can be equally accurate anyway.
if you want to switch between rates rapidly a 8bit change is twice as quick to implement as a 16 bit one

[flotulopex]

Thanks, Richard