On Sat, 4 Oct 2003, Ken Pergola wrote:

> No one should be calculating SPBRG values by hand with a calculator
> over and over again.

No one should be calculating them with calculators or spreadsheets or
JavaScript web pages or slide rules or looking them up in datasheets;
your compiler's preprocessor lets you implement the SPBRG calculations
in your code with no cost in code space, e.g.,

#define SPBRG_INIT(baud)   (unsigned char)(Fosc / (16. * baud) - 1 + 0.5)

SPBRG = SPBRG_INIT(9600);

Of course, more elaborate schemes are possible that validate the above
macro generates a useful value and detect the appropriate value of
BRGH.

If I see code with

SPBRG = 25;       /* 9600 baud */

the comment is worthless; I still have to verify the math.  And then I
have to reach for my calculator/spreadsheet/whatever if I want to
change the baud rate or the system clock.

--
John W. Temples, III

--
http://www.piclist.com hint: PICList Posts must start with ONE topic:
[PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads