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Douglas Kennedy
Joined: 07 Sep 2003
Posts: 755
Location: Florida
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| PIC24HJ128GP206A |
 Posted: Sat Jan 11, 2014 6:42 pm |
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I have two identical PCB's each with a PIC24HJ128GP206A TQFP 64 pin and both have an identical issue. The issue is PINS RC2 RC1 RG15 RG13 RG12 RG0 RG1 appear dead ( can't get then to go high ).
| Code: | /// notes certain pins aren't working
/// bad pins C1 C2 G15 G13 G12 G14 G0 G1
#include <24HJ128GP206A.h>
#FUSES NOWDT //No Watch Dog Timer
#FUSES CKSFSM //Clock Switching is enabled, fail Safe clock monitor is enabled
#FUSES NOJTAG //JTAG disabled
#device ICSP=1
#use delay(crystal=40MHz)
#use rs232(debugger)
void main()
{
delay_ms(200);
output_g(0xFFFF);
while(TRUE)
{
delay_ms(200);
output_g(0xFFFF);
delay_ms(200);
output_g(0x0000);
Printf("hello\n\r");
}
} |
G6 G7 G8 flash a led.....I have tested every trace back to the board
It is just the 8 pins around the top corner of the PIC chip that are failing.
Failing pins aren't shorted to ground.
Any ideas? No hurry since I can do without the pins. |
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temtronic
Joined: 01 Jul 2010
Posts: 9232
Location: Greensville,Ontario
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| Posted: Sun Jan 12, 2014 6:46 am |
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Im not a '24' user but..
I know you've probably thought of it but are there 'default' peripherals on those pins ? Or are they 'programmable pins' that aren't properly 'programmed'.
hmm.. are those pins shorted to each other ? Have you a 3rd unpopulated PCB to examine and a real good magnifyer.
hth
jay |
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Douglas Kennedy
Joined: 07 Sep 2003
Posts: 755
Location: Florida
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| Posted: Sun Jan 12, 2014 9:15 am |
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I have a 3rd unpopulated board and there are no shorts or disconnects.
On the failing boards with the PIC24 none of the failed pins are shorted to each other. There is continuity from the PCB to the pin as it enters the PIC's plastic package. Suspects are the chip dies for the few chips I have and the CCS compiler database set up for this chip. The PIC chips are cheap enough I'll get another batch and swap one chip to see if the problem persists. |
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asmallri
Joined: 12 Aug 2004
Posts: 1635
Location: Perth, Australia
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| Posted: Sun Jan 12, 2014 10:47 am |
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| Douglas Kennedy wrote: | I have a 3rd unpopulated board and there are no shorts or disconnects.
On the failing boards with the PIC24 none of the failed pins are shorted to each other. There is continuity from the PCB to the pin as it enters the PIC's plastic package. Suspects are the chip dies for the few chips I have and the CCS compiler database set up for this chip. The PIC chips are cheap enough I'll get another batch and swap one chip to see if the problem persists. |
Did you check all VDD and VSS connections are ok especially the ones near the problem pins?
_________________
Regards, Andrew
http://www.brushelectronics.com/software
Home of Ethernet, SD card and Encrypted Serial Bootloaders for PICs!! |
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Douglas Kennedy
Joined: 07 Sep 2003
Posts: 755
Location: Florida
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| Posted: Sun Jan 12, 2014 1:38 pm |
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Thanks asmallri as you suggested, it was a bad cold solder VSS connection same place on both boards oops.
Maybe the thermal sink (ground plane) on the ground connection didn't help.
You know sometimes I fixate on the pins at issue and since it was replicated on another board ended up convincing myself the wrong answer was the correct answer. |
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