Kulwinder Atwal wrote:
>
> So then:
>
> void count(int time)
> {
> int value = 0;
> while (value < time) {
> while (inb(BASEPORT+1) & 0x80);
> while (inb(BASEPORT+1) ^ 0x80);
> value++;
>
> }
> }
I haven't tried it out yet, but I don't think this function will work...
This is the situation:
I have a 109 kHz signal on pin 11 of my parallel port. I want to count
10000 pulses.
so... first i do
while (inb(BASEPORT+1) & 0x80);
to check if it's high. This means if the parallel port was 1XXXXXX then
with this AND function i get:
1XXXXXXX
10000000
-------- (AND)
10000000
Which is a decimal value of 2^7=128, which is not zero, so I will stay
in this loop until i get 0XXXXXXX.
Then, after the bit on pin 11 went low, i have to stay in a while loop
until it gets back high... if i do that lik you say, with XOR, then i
get:
0XXXXXXX
10000000
-------- (XOR)
1XXXXXXX
which is ok for the moment, but let's say that the bin on pin 11 gets
low and i get 0XXXXXX then normally i should leave the while loop, but
it is not sure if that will happen, because one of the X's could be
non-zero and that means i will stay in the while loop. So i guess it's
better to say
do
{
klok = inb(BASEPORT+1) & 0x80;
}
while (klok == 0);
because this will give me:
0XXXXXXX
10000000
-------- (AND)
00000000
And here I'm sure that i have a value of zero!
If someone else has a better idea of a routine to count the amount of
pulses that arrives on pin 11 of the parallel port, then please let me
know! The algorithm I'm using right now is:
void count(int time)
{
int value = 0;
int clock;
while (value < time) {
do
{
clock = inb(BASEPORT+1) & 0x80;
}
while (clock == 0);
do
{
clock = inb(BASEPORT+1) & 0x80;
}
while (clock == 0x80);
value++;
}
}
Greetzzz
MC303
--
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