problem detecting pic18f2550

[babinton]

Hello, I am using melab software and EPIC programmer to program pic, I just bought a new PIC18F2550 and when I try to use melab to detect it, I got error message that it can't detect the pic. pls, can you tell me what could be the problem.

 

[bigdogguru]

There maybe a modification required depending on the revision of your adapter socket:

Modification for the 40/28 ZIF Adapter
(Part # 4028Z)

Only perform this modification on adapter revision 95181 or 01189.

Perform this modification if you have trouble programming 28-pin PIC18Fxxx devices that require a AVdd connection on pin 7, such as 18F2331 and 18F2431.

Only change the back (solder side) of the printed circuit board.

Solder a wire between the pins as shown. 26-30 gauge wire-wrap wire can be used.

Modifications for EPIC™ Adapters

If this is not the issue, ensure you are using the latest revision of the software.

Hope the info helps,

BigDog

---------- Post added at 19:55 ---------- Previous post was at 19:49 ----------

I also found this recommendation for 18FXXXX devices:

Programmer Modification - PIC18Fxxxx devices

If you have problems programming an 18F series PICmicro, it may be necessary to add a small capacitor to the output connector (J3) of the programmer, or to the target board, if the device is being programmed in-circuit. (If you already have 0.1uF bypass caps on your target board, it isn't necessary to add more.)

This modification can be performed on either EPIC Programmer or melabs Serial Programmer. The additional capacitor will not degrade performance for any of the unaffected PICmicros.

A 0.1uF monolithic capacitor should be added between Vdd and ground. The best place to add this capacitor on the programmer would be on the back side of the board soldered directly to connector J3 between pins 4 (Vdd) and 10 (ground). The addition of this capacitor does not interfere with the programming of other devices.

This modification can be done to either the EPIC or Serial Programmer.

Programmer Modification - PIC18Fxxxx devices

Also ensure the device is not code protected.

BigDog

 

[babinton]

thanks for your suggestion bigdogguru, the modification according to the link you provided is for 18F2331 and 18F2431 but the PIC i have problem with is 18F2550 and according to the datasheet pin7 is RA5/AN4/SS/HLVDIN/C2OUT, or will the solution work as long as the PIC is within the 18Fxxx series

 

[bigdogguru]

The requirement of recommendation #1 is "8-pin PIC18Fxxx devices that require a AVdd connection on pin 7" and both 18F2331 and 18F2431 are examples. I didn't check the datasheet for the 18F2550 to see if it applied.

However, recommendation #2 concerning the addition of a capacitor seems to apply to all 18FXXXX series. I would give the second recommendation a try first before examining the possibility of recommendation #1

You may have to refresh your page before seeing recommendation #2, it was added later to the posting.

BigDog

 

[babinton]

Thanks, also when I went through my design of epic programmer, I found out that I didn't add a pull down resistor for the PGM pin of the 28pin 18F2550, although I can use the programmer without the PGM pull down to program all other PIC except for the pic in question. So, is it totally necessary for the PGM pin to be pull down to ground.

 

[babinton]

issues with PIC a8f2550 programming

Hello Bigdogguru, thanks for your suggestions, I can now program detect the 18F2550 on my Epic programmer and when I run auto-detect command on melab software, i found the pic but the main problems is sometime when I program the pic and read back it shows that the chip was programmed well but when I plugged the pic inside my board and plug the usb connector to a system, the system will show can not recognized usb device. Please, can you tell me what I am doing wrong.
Regards

Don't start new thread with the same content. Threads merged [alexan_e]