Intermittent MCLoader Connection

[wfran93023]

Requesting any suggestions as to why my MCLoader connects to my 16F877A only intermittently. I'm using a laptop with USB to serial cable, RS232 converter, PBP, and MCStudio Plus. In my programming up to this time I've plugged and unplugged the PIC in the MEL programmer. I decided to try the bootloader to make life a little easier and loaded the 20mhz bootloader software onto the 877A. Then attempted to download a short sample program (from July 06 Nuts&Volts). On about 1 out of 15 tries, the thing loads successfully and the sample program runs. The rest of the time I get the "unable to connect to the target pic" message. I've changed everything I can think of. It seems to be a timing thing. It will intermittently load the short sample program, but won't even get started on my long project program before it fails. Sometimes USB to serial cables are flaky, but I've had no problems with the two that I've been using with my ham equipment. All I can think to do now is buy another USB cable and see if that makes a difference. Help!

Wayne Francis
Ojai, CA

[Dave]

wfran93023, Make sure the baudrate is set to the slowest in the MCloader window as some of the USB to RS232 convertors I have used in the past can't keep up with the data rate..

Dave Purola,
N8NTA

[skimask]

I'm using a laptop with USB to serial cable, RS232 converter, PBP, and MCStudio Plus.

I've had problems in the past with laptops, intermittent programmer connections, etc.etc....
In my case, the fix was to disable the temperature/fan/voltage monitoring programs that ran under Windows.
I noticed that whenever those programs updated (every 5 seconds, 10 seconds, whatever), the connection would dump.
Usually, I never had a problem because I'd disable that stuff. Every once in awhile, I'd have a swarm of problems. Come to find out, it was usually right after the wife would use the laptop and actually turn it off when she was done with it rather than hibernate it...hence those programs restarting!

[Bruce]

I'm betting it's your USB/Serial converter. I had one that caused me a lot grief on a laptop. Same symptoms. If you can, try to find one with an FTDI chip-set.

[wfran93023]

Thanks to all who responded. In the interim I've reloaded everything on a desktop and the thing runs like a champ. I'll continue to experiment with the laptop, and look for a new USB cable as opportunity permits. I'm operational now, but would really like to identify the problem. Might uncover some characteristic that will be valuable in the future. Thanks again.
Wayne