#use fast_IO(c)

[acid]

HELLO
If I do use fast_IO(c) in the my code, the portc doesn't function. If I do use standard_io the Portc is right,

#include <18F252.h>
#device adc=8
#use delay(clock=40000000,RESTART_WDT)
#fuses H4,PUT,BROWNOUT,WDT1,nolvp
#use fast_io(c)

set_tris_C(0);

do {

output_high(PIN_c0);

output_low(PIN_c0);
restart_wdt();
} while(1);

Some idea?
Thank in advance
Albert
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This message was ported from CCS's old forum
Original Post ID: 144515111

[R.J.Hamlett]

:=HELLO
:=If I do use fast_IO(c) in the my code, the portc doesn't function. If I do use standard_io the Portc is right,
:=
:=#include <18F252.h>
:=#device adc=8
:=#use delay(clock=40000000,RESTART_WDT)
:=#fuses H4,PUT,BROWNOUT,WDT1,nolvp
:=#use fast_io(c)
:=
:=set_tris_C(0);
:=
:=do {
:=
:=output_high(PIN_c0);
:=
:=output_low(PIN_c0);
:=restart_wdt();
:=} while(1);
:=
:=Some idea?
:=Thank in advance
:=Albert
I think you will find, it is working, but is now too fast!...
The problem is that the bit set/reset functions, do a read modify write cycle. Now with standard IO, there is also an access to the TRIS register, which allows time for the signal to settle. Unfortunately, if instead you use fast_io, and do two operations in rapid sequence like this, there is not time for the chip to respond. There are warnings about this in the MicroChip data sheets, and 'example' files for the PIC.
Stick a tiny delay between setting, and clearing the bit.

Best Wishes
___________________________
This message was ported from CCS's old forum
Original Post ID: 144515117