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Tuesday, April 7, 2009

Classic PIC Programmer

PICs are small microprocessors containing RAM, ROM, and some peripherals. Almost no other parts are required to make a complete “embedded system”. They are readily available and well supported by the manufacturer, third party developers, and most importantly, users. This has led to their immense popularity.


The PC board design is fairly straightforward and can be made by laser printing to special paper or a page from TIME magazine, then ironing the image onto copper-clad board, then etching with ferric chloride. There are a few jumper wires. The power source needs to be at least 15 volts. A 12 volt DC adapter usually produces about 17 volts, so that's a good choice. Two 9-volt batteries in series will work too. Solder directly to the PC board or use a connector that mates with your power source. Pay attention to the direction of the voltage regulators because the plastic regulators are backward from the tab type. Substitute Japanese or European generic equivalents for the transistors and diodes, but remember that the pinouts will be different. A right angle PC mount DB-25M connector is specified, but a conventional solder-cup DB-25M connector works, see the picture how I did it.


The programmer connects to the parallel printer port of your computer and requires external power. If you want to program a PIC you'll have a hex file created by your assembler or created by someone else(see my propeller clock). You will also need to drive the programmer with some software. Here are programs that run under DOS and Windows. Linux software for Intel-based computers is available elsewhere. Macintoshes do not have parallel ports and can't use this programmer. Do not insert the PIC to be programmed until you have power applied and have run the software, and the programming LED is not lit. The DOS software requires command line switches for fuse settings(unless in the chip's hex file)and also the environmental variable "set ppsetup=3" to be typed before running the program. The Windows software requires the driver "dtait.drv" to be in the \windows\system directory and also the line "PINAPI=DTAIT.DRV" added to the system.ini file. Tell the software you have 7407 chip and PNP transistors. These details are explained in the text files included with the software.

The Files:

DOS software by David Tait "".
Windows software v1.03 by Silicon Studio "".

Programming newer PICs:

  • The whole “F” series can be programmed. You need to use newer software, like this cool software. The PIC16F627 and PIC16F628 are 18 pin devices and fit right in the socket, but you must make a ground connection to pin 10 to prevent LVP programming, a new feature this programmer does not use. Some people suggest using a 10K resistor to ground, if you are doing in-circuit programming that probably makes sense. Programming the bigger PICs, including the PIC16F872 through 16F877 requires fitting the correct(28 or 40 pin) socket and wiring the pins to the corresponding function. Remember to ground the LVP pin on these, too. The bigger PICs also have extra power and ground pins. These must all be used.
  • You must select the port your computer is using(usually 0378) and the type of programmer (P16PRO) and the type of buffers the programmer uses (non-inverting). The software is beta, but I have tested it and can testify it working on the 16F84 and 16F628 I tried. It only programs locations used in the hex file, so it is very fast. If your program is 250 bytes, only 250 bytes get programmed, but when I used my PicstartPlus to verify the chips I tried, it would show a verify error unless I blanked the chip first, although the chip functioned fine. Leaving those unused areas in the previously programmed state shouldn’t be a problem.
  • Propic2 keeps the power to the chip on while idle. This can be useful for “burn and crash” in-circuit programming. You’ll see the LED is lit. I don’t like to insert or remove the PIC when power is present, so I pull the power cord before I insert or remove the PIC.
  • propic2 software, in case the above link is broken.

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