David Tait vs JDM PIC programmer, how to choose ?

[pkshima]

Hi,

As the subject suggests I am confused on how to decide which type of programmer to use. Last weekend I built the p16pro and had little luck with it. once in say 50 times, it programmed my 16f628 well and gave the dreaded 'program verify failed'/'config fuses verify error' in the rest.
Lot of playing with the 330pf capacitor etc was of little help but could never get it to 100% reliability. I have check the MCLR voltage and the cable length etc too. no use

I was wondering if a JDM would be any better in stability/reliability.

Thanks & Regards,
Pradeep K. Shima

 

[eblc1388]

During programming the 16F628, did you do anything to Pin10 "RB4/PGM" pin?

This pin should be pull to ground in order to program the PIC sucessfully.

Perhaps you would consider upgrade the programmer design to P16Pro40 shown here:

I have up to now built more than five parallel port type programmers and none of them give me any verifying error. I took no particular care about cable length and I don't need added capacitors to data and clock line.

See that thread here: PIC programmer & WinPicProg

The JDM design requires only a few components and is easy to build, even if it do not work at the end. If you want to build the JDM design, take a look at the comment mentioned in the STICKY FAQ of this forum.

 

[pkshima]

Hi eblc1388,

thanks for replying.

I incorrectly wrote p16pro. What i actually built was p16pro40. I used a 18 pin IC socket thats why wrote p16pro.

Is the pin 10 supposed to be grounded directly or through a resistor ? I recall I did try putting a resistor between pin 10 and GND but didnt get any better results.

After that I took out the starred components shown in the schematics, the 330pf cap and the 10k resistor and thats when the programmer started working once in a while before that it just didnt work and failed on adress 0000h itself.

thanks again

 

[eblc1388]

Is the pin 10 supposed to be grounded directly or through a resistor ? I recall I did try putting a resistor between pin 10 and GND but didnt get any better results.

Direct ground or via a resistor smaller than 10K are both OK.

After that I took out the starred components shown in the schematics, the 330pf cap and the 10k resistor and thats when the programmer started working once in a while before that it just didnt work and failed on adress 0000h itself.

Trace the connection at Pin4(MCLR/Vpp) of the socket. There should be a 680R resistor to ground. Measure the resistance(without PIC in socket) of pin4 to GND with power off to make sure it is there.

Also you would run into difficulties if you have set up the PIC to use internal oscillator because once you apply power to it, it will run. Once it is running its code, it will not enter programming mode again, unless it is reset and Vpp applied immediately. If you are using WinPicPro, you can also try setting the "Vpp delay" to 0 under the hardware tab.

I would suggest trying different programming softwares as some can apply Vpp before Vdd, which is what the 16F628A needed but not 16F628. Many users have sucess changing to a different programming software.

Are you using an "A" version PIC or just the 628 version?

 

[pkshima]

Thanks. I will try the resistor on Pin 10 and re-checking the resistance at pin 4 when I get my hands again on the programmer. But do you believe that this can be the cause of a 'un-stable' programmer ? Wouldnt it not work at all if this were the cause ?

I had already tried playing with the delays. But no set of values ever made it working all the time. It stayed random

One more query. I am going to buy a laptop in distant future. Are there any issues I might encounter when using the P16pro40 with a laptop (assuming ofcourse that it has a parallel port) ?

 

[eblc1388]

Thanks. I will try the resistor on Pin 10 and re-checking the resistance at pin 4 when I get my hands again on the programmer. But do you believe that this can be the cause of a 'un-stable' programmer ? Wouldnt it not work at all if this were the cause ?

There are many causes for a programmer not to behave correctly and I have just offered suggestions for you to troubleshoot the circuit.

Do "read" on a PIC for several times. Does it read the data back from the PIC 100% exactly every time or different data values are read back?

Have you tried other programming software?

There could be other hardware or software reasons like Operating system as one user of this forum said he could never got his programmer to work under WinXp, while many said they do. I am using Win98SE so I don't know.

One more query. I am going to buy a laptop in distant future. Are there any issues I might encounter when using the P16pro40 with a laptop (assuming ofcourse that it has a parallel port) ?

The P16Pro40 works on any standard parallel port, including that of the laptop.

 

[pkshima]

No, the read does not suceed every time. It succeeds say just once and then it goes bad and finally blank.

The first time the programming suceeded, I took the pic out, placed it in the circuit and verified that it did what it was supposed to (Nigels tutorial 1.2) and it did work fine.

Yes, I have used picallw, winpic and icprog with Nigels winpic giving the best results with the vpp delay set to 0 and MCLR delay to 17.

thanks again for hanging on