Olimex Support Forum

Microcontrollers => PIC => Topic started by: olimer on December 31, 2013, 08:39:09 pm

Title: PIC-MCP-USB communication timeout
Post by: olimer on December 31, 2013, 08:39:09 pm
I have been using a PIC-MCP-USB with MPLAB 8.88 as a PicStart-Plus with success for some time now. Recently I started noticing a whining buzz sound come from the programmer, especially when actively programming. I did not pay much attention to it. I kept programming 18F4331's and 18F4525's and kept getting weird behavior, like saw tooth waves on a simple (TRISB = 0; PORTB = 0xff;) program.

Eventually after changing more code, the programmer started experiencing "serial time out" errors when trying to program a chip. The red LED would no longer blink, just time outs. I tried new chips, I removed and replugged the USB cable, I rebooted computer, and verified the right COM port number, even trying other USB ports. The green power LED is on, and the whining buzz is still there, but no function.

Now I can't even successfully enable the programmer. I get the error "PICSTART Plus not found. Please verify serial connection and try the current operation again". It can't be completely dead because if I remove the cable or switch ports, I do get a different error message "Com port 7 could not be opened."

I am thinking some component got damaged but there was almost no physical stress to the programmer during the time it failed apart from operating the ZIF socket to change chips. I tried to look for any signs of burns but did not spot anything. I did spot a messy solder point on the back between a thru-hole resistor on the front and a surface-mount resistor on the back near the QFN chip.

I also found that if I apply a little bit of finger pressure to certain spots of the traces that go between the QFN on the back and the on-board 18F252 PIC on the front, the RED LED lights up and the sound changes pitch. If I try enabling the programmer with finger pressed I get another message "Cannot Transmit. Please verify connection and retry the previous operation." I do not think this should happen.

Any idea what could be wrong? What component's physical connection is most likely to cause this? Any known field failures? I am hesitant to purchase a new one, and if I did, I might look for something compatible with MPLAB X, but I'd prefer to get this one running. I used to be happy with it. Any help would be appreciated.

Title: Re: PIC-MCP-USB communication timeout
Post by: LubOlimex on January 29, 2014, 04:46:45 pm
Hey olimex,

I believe we communicated over the support e-mail. Right?

How'd everything go in the end?

Best regards,