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GregN
Joined: 06 May 2008
Posts: 2
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| Switching random I/O. |
 Posted: Tue May 06, 2008 2:52 am |
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Hi. I am using a 16F684 PIC to produce a random output when AN3 is below 300. I am using a 0-5v solar panel on the analog input and for some reason the panel is producing 0v in light when connected. If i directly connect AN3 to 5v it does work but draws 100mA. I am guessing it has something to do with output_a(r). But i dont know any other way to output a random pin, does anybody know a way that will work? My code is:
| Code: | #define RAND_MAX 3 // Change to an appropriate number
#include <stdlib.h>
int16 adc;
int r;
void main()
{
setup_adc_ports(sAN3|VSS_VDD);
setup_adc(ADC_CLOCK_INTERNAL);
set_adc_channel(3);
setup_vref(FALSE);
setup_comparator(NC_NC_NC_NC);
while(1){
r=rand();
adc=Read_Adc();
if(adc<300)
output_a(r);
else
output_bit(PIN_A0,0);
output_bit(PIN_A1,0);
output_bit(PIN_A2,0);
output_bit(PIN_A3,0);
}
}
} |
Thanks. |
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Ttelmah
Guest
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| Posted: Tue May 06, 2008 3:03 am |
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Add the line '#use fast_io(a)' below the stdlib include, and then at the start of your main, add 'set_tris_a(0b11110000);'.
The problem is that with 'standard_io' mode selected (the default), as soon as you output a full byte the port, the whole port is changed to operate as an output. The reprograms the tris for RA4, to an output...
The changes above, _fix_ the tris settings, so that this doesn't happen.
Best Wishes |
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GregN
Joined: 06 May 2008
Posts: 2
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| Posted: Tue May 06, 2008 3:18 am |
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| Ok great it works. Thanks. |
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