> I have been shooting for 115200 with out any luck

Hi Bill,

Section 20.1 of DS39623B outlines how to select a baud rate

(it's been a little while since I did this, apologies for any errors)

BRGH =3D 0

((Fosc/baud rate)/64)-1

((20000000/9600)/64)-1

BRG =3D 31.55

((20000000/115200)/64)-1

BRG =3D 1.71

With BRGH =3D 1

((20000000/115200)/16)-1

BRG =3D 9.85 (call it 10)

The actual baud rate is

20000000/(16(10+1))

=3D 113636

with an error of (113636 -115200)/115200 =3D 1.36% slow. This would
probably not be a problem if each frame is synched. For long streams
with no reference the receiver will drift away from the incoming data

A 'hexadecimal' crystal is more suitable for common baud rates, but
whether you can or do use one depends on the functional priorities. For
example if a microsecond timer is more important than comms, then a
20MHz would be preferable (for the 200ns cycles). You might have to
compromise somewhere

An 18.432MHz crystal in the calculations

((18432000/115200)/16)-1

=3D 9.000000, no error

Joe
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