Covington Innovations

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NOPPP, the "No-Parts" PIC Programmer

Last revised 2000 October 21

(Picture of NOPPP)

NOPPP is a simple programmer for PIC16C84, PIC16F83, and PIC16F84(A) microcontrollers. It attaches to the parallel port of a PC. Plans were published in Electronics Now Magazine, September, 1998, and are included in shorter form in the downloadable ZIP file.

An article about this programmer also appeared in Silicon Chip (Australia), March, 1999.

Download NOPPP.ZIP now

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Kits available!
Updated software!
Updated circuit!

Want to program a chip other than PIC16C84, 'F83, or 'F84? Don't look here. Instead, look at the low-cost programmers and kits from Dontronics.
No e-mail please...

Thank you for your interest in NOPPP. After corresponding with over 500 people who have built NOPPP, I'm confident that it works reliably.

I am getting more e-mail about NOPPP than I can answer. I do not get any continuing income from the NOPPP project, so as far as I'm concerned, it's a finished project and I can't devote several hours a week to unpaid user support. Please get help locally if you can't get your NOPPP to work, since almost all inoperative NOPPPs are due to wiring errors. (Mixing up the leads of Q1 is the most common error; cheap assorted transistors often do not have the pins in the arrangement described on the box!) I can't see, or fix, a wiring error remotely. If you're sure there's not a wiring error, then either your PC parallel port is out of specification or you have a defective PIC chip.

If you must contact me, please read this entire document carefully before doing so. Your questions are already answered here.

If you are having problems with the Ramsey or Oatley kit, you should contact the kit manufacturer for help, and have them contact me if there is a problem they cannot resolve.

If you have a substantial technical question, not answered here, about the Electronics Now article, you can submit it to that magazine at q&a; Their Q&A; column is written by me, but it takes an average of six months between receipt of a question and publication of the answer.

I cannot design circuits free of charge, nor can I give free programming assistance to anyone other than my own students at the University of Georgia. If needed, I can do custom design work for US $75 to $100 per hour.

-- Michael Covington

Having problems learning to use MPLAB? See these brief notes. For further assistance contact Microchip; MPLAB is their product, not mine.
What's new:

Although not precisely "no parts," NOPPP is unusually simple and uses no hard-to-find parts. You can probably build it using parts you already have on hand. Here's the circuit (revised somewhat from the original design, for greater reliability):

(Revised circuit)
Pin numbers are those of the 25-pin connector on the PC.

Capacitors are in microfarads.

Circuit description: On the PIC, pin MCLR is +5V for normal operation (not used here), +12V for writing, and 0V for resetting. Crucially, the +12V supply does not actually "burn an EPROM" -- the higher voltage is merely a signal to activate the internal flash memory programming circuit. It must be greater than 12.0 volts. The D0 output of from the PC controls this signal. No harm results from applying it at inopportune times.

The PIC communicates by means of a two-wire (plus ground) synchronous serial protocol. Pin B6 is the strobe signal; pulses on it tell the PIC when to accept or transmit each next bit of data. Pin B7 is both an input and an output. When the PIC is receiving from the PC, SLCTIN is held low and D2 does not conduct; D1 and R1 are effectively out of the circuit, and the PIC receives data from AUTOFD.

When the PIC is sending, SLCTIN and AUTOFD are high, D1 does not conduct, and D2 and R1 provide pull-up. Some additional pull-up is provided by R2 plus the pull-up resistor on AUTOFD inside the PC's parallel port (nominally 4.7k, sometimes much lower in newer CMOS parallel ports). The PC reads the data on the BUSY pin, which is 0.6 volt higher than the output of the PIC because of D2. The PC parallel port has (or should have) CMOS or Schmitt inputs and should not require true TTL logic levels.

R2 and R3 help to reduce cable crosstalk by isolating the input capacitance of the PIC so that less current flows during sudden transitions. The PIC has Schmitt inputs and does not object to the resulting reduction in rise time. R4 protects the base of Q1.

Revised circuit: The circuit originally published in Electronics Now and software are quite reliable. However, for greater compatibility with a few PC parallel ports that had trouble with the original, I made some slight changes and additions:

If you have the original circuit working, there is no need to make these changes. However, a very few PCs with nonstandard parallel ports or poor-quality cables benefit from them.

Parts Substitutions

1N914 = 1N4148
1N34 = OA76
2N2222 = MPS2222 = 2N3904 = MPS3904

Frequently asked questions about NOPPP