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drolleman Guest
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628 can't make a3,a4 output |
Posted: Fri Mar 12, 2004 2:10 pm |
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I can't make the 628 output on a3 and a 4. i created a minimum progran to test for output. but nothing i try works. can anyone help?
#include <16f628.h>
#fuses intrc,WDT,PROTECT,NOBROWNOUT,PUT,NOLVP,NOCPD
#use delay(clock=4000000)
//#use rs232(baud=9600, xmit=PIN_B2, rcv=PIN_B1,enable=pin_a0) // Jumpers: 8
//#use fixed_io(a_outputs=pin_a0, pin_a1, pin_a2, pin_a3, pin_a4)
//#use fixed_io(a_outputs=pin_a0, pin_a1, pin_a2, pin_a3, pin_a4)
/////////////////////////////////////////////////////////////////////////////////
/////////////////////////////////////////////////////////////////////////////////
/////////////////////////////////////////////////////////////////////////////////
///////////////////// MAIN ///////////////////////////////////////
/////////////////////////////////////////////////////////////////////////////////
/////////////////////////////////////////////////////////////////////////////////
/////////////////////////////////////////////////////////////////////////////////
main()
{
//set_tris_b(0x00);
set_tris_a(0x00);
//setup_ccp1(ccp_off);
//setup_comparator(a0_a3_a1_a2);
//output_low(PIN_A0);
output_high(PIN_A3);
output_high(PIN_A4);
// for setting the calibration of the rev limiter
//ground the pin on start then within 5 sec then release
// this puts the chip into calibration mode
while(1)
{
output_high(PIN_A0);
output_high(PIN_A1);
output_high(PIN_A2);
output_high(PIN_A3);
output_high(PIN_A4);
delay_ms(500);
output_low(PIN_A0);
output_low(PIN_A1);
output_low(PIN_A2);
output_low(PIN_A3);
output_low(PIN_A4);
delay_ms(500);
}
return 0;
} |
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dyeatman
Joined: 06 Sep 2003 Posts: 1924 Location: Norman, OK
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RA3/RA4 |
Posted: Fri Mar 12, 2004 2:28 pm |
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According to the 16F628 data sheet RA4/AN4 is open collector
so you will need a pullup resistor there.
Try adding the line:
setup_comparator(NC_NC_NC_NC);
To make sure the the comparators are turned off and the pins are in digital mode. |
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drolleman Guest
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Posted: Fri Mar 12, 2004 3:40 pm |
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that fixed a4 but a3 still doesn't work i know the output works because when the device wasn't programed the led that is connected to the pin was on. I added the nc on the comparater that was sugessted. is there somthing else i need to do? |
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asjad
Joined: 09 Mar 2004 Posts: 52 Location: Greater Manchester - UK
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analog pins |
Posted: Fri Mar 12, 2004 4:27 pm |
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Hi,
I have looked at the datasheet and it seems that when ever your
pic and most pics are powerd up PORTA is not configured as
digital Input/Output
Look at the top right of page 31 of the datasheet.
To cure this you need to look at the A/D convertor commands.
one of the commands will set diffrent pins on port A to digital. _________________ Best Regards |
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drolleman Guest
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Posted: Fri Mar 12, 2004 5:47 pm |
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the 628 doesn't have a/d convereter. |
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Ttelmah Guest
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Posted: Sat Mar 13, 2004 9:04 am |
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drolleman wrote: | the 628 doesn't have a/d convereter. |
Try adding 'SETUP_CCP(CCP_OFF);'.
A3, is multiplexed to the comparator (as you have allready found), and to the CCP. It may be waking up you this enabled.
Best Wishes |
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