If you are constructing a PIC based project like the "Pic-a-Switch" (see RadCom September-December 2001) designed by Peter Rhodes (G3XJP), you will need a PIC Programmer.
The PIC programmer has two parts: the hardware and the software. Connected to your PC, the hardware part acts as an interface between the PC and the actual PIC chip package. The software part runs on the PC and delivers the machine code program on to the actual PIC via the programmer hardware.
The unprogrammed PIC may be plugged into the programmer hardware itself as in the picture above (though the ‘in situ’ lead would be removed then). When the program has been loaded into the PIC you can physically unplug it, taking care not to damage the pins, and then plug it into your project. Or you can plug the unprogrammed PIC into your project and then connect a lead between the programmer and your project (so the PIC socket on the programmer would be empty then). The lead allows ‘in situ’ programming and avoids transferring the PIC and damaging its pins.
I used David Tait’s Topic version 3 design. I found the DOS programmer software and all the details for constructing the hardware in the topic03.zip file at:
David Tait’s PIC Archive. Topic03.zip also contains debug.exe (a test program), problems.txt (problems & suggestions), and walk.hex (a small program).
Peter Rhodes gives excellent advice on "Etching The Board" in his Pic-a-Switch article in RadCom October 2001.
To start with, the programmer would not work with my PC. The debug.exe program came in useful and showed up a problem reading pin RB7. Problems.txt came to the rescue and following the suggestion of adding a diode for the SEL line fixed this. I did not try the suggested extra pull-up resistor. The fix allowed the walk.hex program to load into a PIC from my old 486 PC via the parallel port. The PC was running a DOS window under Windows 95 using the topic03.exe software.
David Tait also offers Windows based programmer software at David Tait’s PIC links . The zip file with the software shows schematics of all his programmers. He suggests the PMICP as being very simple – it uses a serial port connection to the PC.
You can write your own PIC programs or amend existing ones using the MPLAB IDE software downloaded from Microchip's Development Tools .