JDM With External Power - Some Help Needed

[sole_developer]

I have designed the following, however for some reason it is not working! I'am probably going to scrap this, but I though I would check with u guys one last time!...........

View attachment FINAL BOARD.pdf

Everythiing seems to be workign when I test the pins...but when I try to program something, nothing works.........Iam probably going to scrap it and try to build a USB Programmer........but I just don't get why its not working........Everything seems to be fine on pencil and paper!!!

thanks again

 

[spiralbrain]

are you using a USB to serial converter for this? if you are then it will not work because JDM makes use of negative voltage from the serial port. JDM works great on a native serial port.

 

[sole_developer]

Well...actually i looked at couple of designs and made this myself......I am supplying external voltage to the board...the problem is everything seems OK when I even test the voltages....but it doesn't program anything...........
I am getting 5v on VCC and VSS is grounded.......and the PGC & PGD when they are high give me 8 volts........I am using a COM PORT, not USB

But still, i don't know why it is not programming anything........i tried programming a 24C02 chip, it didn't work.......Anyways, I think i will try to make a PIKIT2 clone or something......

I mean, even when I don't put a chip and click on read.....the programming software is reading all 00's from somewhere!!!.........and programming also, i see that data flowing (have put LEDs) but still nothing...!!

 

[spiralbrain]

well your design lacks voltage limiting diodes, try and assemble the real JDM, it works well. Even if you buil a clone PIC Kit 2 you need a way to program the PIC kit firmware. beware 8volts on PGC and PGD can damage the PIC.

 

[sole_developer]

Thank you...I completely forgot about those!!! NO wonder...anyways......will check what happens after I add them....and in the meantime......I have though about making a power supply (Variable), switch for either 12V or 13V (some chips need 12V!)........The LM317.bmp LM317 structure, the one I have designed is in the pdf....Could you please help me with your experiance whether or not what I have designed will work...

THanks in advance!

(PS: I used the voltage calculator on LM317 Voltage Calculator - Electric Circuit)

PS: the '+13/+12' pin iwll be hte output based on posiution of the switch PWR