Easypic 4 with 18f8720 -- won't program

[matty]

I have an Easypic 4+microICD and am using Mikrobasic Pro. Checking through the supported pics, I found the 18f8720 and thought it would fit the bill. I also ordered an 80 pin tqfp break-out board and a perf board. I soldered up the breakout board with the 18f8720 and on the perf board, I point to point wired an adapter to 40 pin dip based on the pin descriptions for the 16f877A I am currently using. I am using the 16f877A without issue.

I have visually checked the pins on tqfp80 for bridges and joint quality multiple times. I verified wiring twice on the adapter after wiring it.

I have powered up the pic, verified it is blank with the programmer, read it (retrieving configuration settings), and can verify it successfully.(with the content read from it) When I attempt to program it, It goes through the programming as though it is succeeding until it verifies the data. It gives program 117 errors; data 215 errors. Programming failed! (This number changes with the program I try to load.)
I am using the bigpic 6/led blinking example provided in the examples.

I have changed jumper 5 on the easypic to the RB5 setting. I left the extra pins floating on the 8720. I was planning to provide pull-downs after proving the chip. All 4 Vss are tied together as well as all 4 Vdd.

I thank you for your time and help,
matt

[cymb]

i use 8722, internal osc with same setup,icsp from ezp5.

8720 needs xtal osc huh?
i did not load all pins till later, was ok

i run ports back to ezp board to use leds!

good luck

[matty]

Thanks for the info. I know now its should work. I didn't know the 8722 had the xtal built in. I am using an 8 MHz now but have tried a 20 and it made no difference. In the absence of any other suggestions, I have ordered another 8720 and an 8520 with breakout boards. I will try again. Maybe there is a physical problem with the chip. It is kind of a soldering-in-the-blind proposition to mount them on the breakout boards. Maybe I lingered too long on a pin... We'll see.

Thanks.

[cymb]

oh i forgot,
a nice mount is "SCHMART BOARD", its easier to place the chip,has tiny grooves with solder in them. ez solder

u can get free samples from microchip. try it,pay shipping

i would suggest the 8722/23. no need for xtal unless timing is critical.

i think your chip is good.??

[matty]

I will definitely look at the Schmart stuff. My chip may be fine, but before I spend too much time troubleshooting it I will see if I can duplicate the behavior with another.

The 8722 is probably in some future plan. I understand the 8722 to be the replacement for the 8720.

While waiting for shipping, I do have a few 16f877a and 18f4550 to play with.
Thanks for the info,
matt

[matty]

Update -- I ordered new a new 18f8720 and 18f8520. The 18f8720 acts exactly as the original one did. The 18f8520 programmed first shot and is running now. So I have proven the rest of the hardware and it looks like I am back to the data sheet. Thanks to all for the input.
--matt