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PIC_evolution
Joined: 16 Jun 2009
Posts: 2
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| PIC18F8722 PORT H I/O "squashes" PIN C5 signal |
 Posted: Tue Jun 16, 2009 4:39 pm |
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PCH V4.079
I have a stubborn issue with PORTH I/O effecting pin C5 on a PIC18F8722. C5 works fine unless any I/O on PORTH comes first. I thought it was an SPI issue, but I finally cut the code down to the following.
| Code: | #include <18F8722.h>
#device ICD=TRUE
#device adc=8
#FUSES NOWDT //No Watch Dog Timer
#FUSES WDT128 //Watch Dog Timer uses 1:128 Postscale
#FUSES HS //High speed Osc (> 4mhz for PCM/PCH) (>10mhz for PCD)
#FUSES NOPROTECT //Code not protected from reading
#FUSES IESO //Internal External Switch Over mode enabled
#FUSES NOBROWNOUT //No brownout reset
#FUSES BORV25 //Brownout reset at 2.5V
#FUSES NOPUT //No Power Up Timer
#FUSES NOCPD //No EE protection
#FUSES STVREN //Stack full/underflow will cause reset
#FUSES NODEBUG //No Debug mode for ICD
#FUSES NOLVP //No low voltage prgming, B3(PIC16) or B5(PIC18) used for I/O
#FUSES NOWRT //Program memory not write protected
#FUSES NOCPB //No Boot Block code protection
#FUSES NOEBTRB //Boot block not protected from table reads
#FUSES NOEBTR //Memory not protected from table reads
#FUSES NOWRTD //Data EEPROM not write protected
#FUSES NOWRTC //configuration not registers write protected
#FUSES NOWRTB //Boot block not write protected
#FUSES FCMEN //Fail-safe clock monitor enabled
#FUSES LPT1OSC //Timer1 configured for low-power operation
#FUSES MCLR //Master Clear pin enabled
#FUSES NOXINST //Extended set extension and Indexed Addressing mode disabled (Legacy mode)
#FUSES MCU //Microcontroller Mode
#FUSES NOWAIT //Wait selections unavailable for Table Reads or Table Writes
#FUSES BW16 //16-bit external bus mode
#FUSES ABW20 //20-bit Address bus
#FUSES ECCPE //Enhanced CCP PWM outpts multiplexed with RE6 thorugh RE3
#use delay(clock=10000000)
#use rs232(baud=19200,parity=N,xmit=PIN_C6,rcv=PIN_C7,bits=8) |
and ....
| Code: | #include "main.h"
void main()
{
setup_adc_ports(NO_ANALOGS|VSS_VDD);
setup_adc(ADC_OFF|ADC_TAD_MUL_0);
setup_psp(PSP_DISABLED);
setup_spi(SPI_SS_DISABLED);
setup_spi2(SPI_SS_DISABLED);
setup_wdt(WDT_OFF);
setup_timer_0(RTCC_INTERNAL);
setup_timer_1(T1_DISABLED);
setup_timer_2(T2_DISABLED,0,1);
setup_timer_3(T3_DISABLED|T3_DIV_BY_1);
setup_timer_4(T4_DISABLED,0,1);
setup_comparator(NC_NC_NC_NC);
setup_vref(FALSE);
// PIN_C5 toggles (below) if this line is commented-out
// Any INPUT or OUTPUT on a PORTH pin "squashes" C5
output_high(PIN_H0);
while(1){
output_bit(PIN_C3, 1);
output_bit(PIN_C5, 1);
output_bit(PIN_B3, 1);
delay_ms(500);
output_bit(PIN_C3, 0);
output_bit(PIN_C5, 0);
output_bit(PIN_B3, 0);
delay_ms(500);
}
} |
I have checked several boards. There are no shorts or tracking problems. In the example above C3 and B3 toggle just fine. But C5 is high at ~0.7 volts and low at 0.
Any suggestions would be very welcome (deadline looming / project stuck).
Thanks! |
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PCM programmer
Joined: 06 Sep 2003
Posts: 21708
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| Posted: Tue Jun 16, 2009 5:05 pm |
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| Quote: | setup_spi(SPI_SS_DISABLED);
setup_spi2(SPI_SS_DISABLED); |
Get rid of these two lines and see what happens.
If that doesn't fix it, then try a striped down program, like this:
| Code: | #include <18F8722.h>
#fuses HS,NOWDT,PUT,NOBROWNOUT,NOLVP
#use delay(clock=10000000)
//=================================
void main()
{
output_high(PIN_H0);
while(1)
{
output_bit(PIN_C5, 1);
delay_ms(500);
output_bit(PIN_C5, 0);
delay_ms(500);
}
} |
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PIC_evolution
Joined: 16 Jun 2009
Posts: 2
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| Posted: Tue Jun 16, 2009 8:48 pm |
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| Thanks PCM programmer. It turned out to be a short after all. |
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