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bcs99
Joined: 22 Nov 2003
Posts: 32
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| Problem with inputs (A4/A5) using 16f688 w/int 8Mhz |
 Posted: Mon Sep 27, 2004 11:48 am |
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I'm having trouble getting the A4 and A5 inputs working on a 16F688. These pins are also used for the oscillator and I suspect that the problem is in the configuration. Has anyone had experience with this chip that could help me out? My test code is posted below.
Thanks.
Bob
| Code: |
#include <16F688.h>
#use delay(clock=8000000)
#fuses NOWDT, INTRC_IO, BROWNOUT, MCLR, NOCPD, NOPUT, NOIESO, NOFCMEN
// PIC PORT MAPPING
#byte _PORTA = 0x105
#byte _PORTC = 0x107
// PIC PIN MAPPING
#bit M1_IN = _PORTA.5
#bit M2_IN = _PORTA.4
#bit M1_OUT = _PORTA.2
#bit M2_OUT = _PORTC.0
void main()
{
set_tris_a( 0b11111000 );
set_tris_c( 0b11000110 );
setup_oscillator( OSC_8MHZ );
setup_adc_ports( sAN5|sAN6|VSS_VDD );
setup_adc( ADC_CLOCK_INTERNAL );
setup_timer_1( T1_DISABLED );
setup_comparator( NC_NC_NC_NC );
setup_vref( FALSE );
while( TRUE )
{
M1_OUT = M1_IN;
M2_OUT = M2_IN;
}
}
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PCM programmer
Joined: 06 Sep 2003
Posts: 21708
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| Posted: Mon Sep 27, 2004 2:34 pm |
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I would try a much more simple test program. First, try toggling
pin A4. (ie., test it as an output). Then edit the code and change
it to toggle pin A5. Once that is working, then set it up to read pin A4
and output that state on Pin A5. (Then do vice-versa).
Don't setup the TRIS. Use the compiler in standard i/o mode (the
default mode) and let it handle the TRIS for this test.
Normally, in a simple test program, I wouldn't setup the ADC ports,
but I looked at the CCS startup code for this chip with PCM 3.212,
and it's not correct. It's supposed to setup port A as all digital and
turn off the A/D. It doesn't do it correctly. So that's why I put those
two lines in there.
| Code: | #include <16F688.h>
#use delay(clock=8000000)
#fuses NOWDT, INTRC_IO, BROWNOUT, MCLR, NOCPD, NOPUT, NOIESO, NOFCMEN
void main()
{
setup_oscillator(OSC_8MHZ);
setup_adc_ports(NO_ANALOGS);
setup_adc(ADC_OFF);
setup_comparator(NC_NC_NC_NC);
while(1)
{
output_high(PIN_A4);
delay_ms(500);
output_low(PIN_A4);
delay_ms(500);
}
} |
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bcs99
Joined: 22 Nov 2003
Posts: 32
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| thanks |
| Posted: Mon Sep 27, 2004 5:35 pm |
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I tried your suggestion and A4/A5 worked good as outputs, using the code you gave. However as inputs the value read was always high which led me to see the circuit problem  . Thanks.
Bob |
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