8 Jul
2006
8 Jul
'06
7:15 p.m.
On 7/8/2006 at 10:44 PM ard at p850ug1.demon.co.uk wrote:
Reading the data sheet showed why
(I was re-loading the mode control register, thus clearing the output
ports). Of course it was trivial to correct in this program, but it sure
made life difficult later.
The typical application of most 8255's, I'm going to guess is that they're
initialized at the start of an application or when the computer is booted
and the mode is never fiddled with thereafter.
Does the 8251 USART also have some sort of strange initialization problem?
It's been a long time since I've used one, but I seem to recall a gotcha.
Cheers,
Chuck