A Printed Circuit Board for the COM84 Programmer The COM84 is a serial port programmer which uses very few components. You will find a schematic at: http://websites.ntl.com/~matthew.rowe/micros/prog.htm For other information from Matthew leave off the prog.htm, (use the /) This is not my design. I just found that it works for me and is cheap and very convenient. I thought it might help others if I shared the construction details. Parts used for the programmer: 1 - DB9F female socket 1/2 - Radio Shack 276-159B printed circuit board 2 - 4.7K 1/4 watt resistors 1 - 1K 1/4 watt resitor 1 - 18 pin low profile DIP socket 1 - 78L05 low power 5 volt regulator 1 - small diode 1N4148 or 1N4002 or similar 1 - electrolytic capacitor 100 mfd ( I used a 47 mfd one ... couldn't find a decent shaped 100 mfd cap - only 5 volts across it) There are two pictures, a top and a bottom view of the board. The top View, (COM84T.JPG): The black rectangle at the bottom is the electrolytic capacitor, (+ end to the left). I was able to bend the leads out and down to holes in the pads. Round caps may be more difficult to position. You may want to consider drilling holes and running leads to the pads on the bottom side of the board. The diode is to the left of the cap, cathode marking to the outside of the board. It is connected to a pad also holding the input to the 5 volt regulator. Above the diode, the black, almost circular part is the regulator. If you face the flat part of the regulator the three pins, left to right are: output, ground and input. Notice the short jumper wire from the middle lead of the regulator to the rightmost of the set of holes above the regulator. The 18 pin socket faces upward and is as high as it can go, leaving the bottom pads free for other components. The rightmost of these turns out to be ground and has black wires to it. This orientation of the PIC socket was choosen so that when the PIC is inserted with the DB9F pointing away from you, the writing on the PIC is in the normal reading position. This helps warn you from inserting it backwards. The pins on the DB9F socket run 1 - 5 top to bottom. Only 3 of these have wires attached: DB9F Pin3, (TXD) - yellow wire - goes to a pad just below PIC pin 9, (also has a 10K resistor and the anode of the diode). The 10K resistor goes to PIC pin 4, (MCLR). DB9F Pin 4, (DTR) - white wire - goes to pad just to left of DB9F pin 1 and has a 4.7K resistor going to PIC pin 13, (RB7). DB9F Pin 5, (GND) - black wire - to pad below PIC pin 10. This pad also has another black wire running to PIC pin 5, (Vss), which has a trace running to a jumper to the center pin of the 5 volt regulator. Capacitor negative is also connected to this pad. Also notice the white jumper from PIC pin 13, (RB7), going to to pad on DB9F pin 8, (CTS). A 4.7K resistor on PIC pin 12, (RB6), connects to DB9F pin 7, (RTS). PIC pin 14, (Vdd) connects by red wires to the output of the 5 volt regulator and + terminal of the capacitor. The Bottom View, (COM84B.JPG): DB9F pins are 9 - 6 top to bottom, 9 and 6 are open and shouldn't touch any pads, 7 and 8 have wires inserted, soldered to pads. Other than the board being jammed between the pins, this is the main support for the board. A little epoxy between the DB9F and board, (outside the pins), wouldn't hurt. There are three areas where the traces have been cut and scrapped away between 3 hole pin pads and the pads on the outer edges. Five have been scrapped away on the right and three at the upper left. Also, on the upper center left, part of a backwards 'L' shaped pad has been scrapped away to create two pads, one for the capacitor + lead and the other for the 10K resistor, yellow wire and diode anode. All unused PIC pins should be soldered to their pads to make the socket stable. Use of the Programmer: The programmer could be plugged directly in a COM port on the computer but might be hard to reach. I use an Atari joystick extension cable to be able to plug and unplug the programmer at a convenient location. Just make sure all the appropriate wires connect through in the cable. I also find it useful to first place the PIC in a machine pin, 18 pin DIP socket which is then placed in the programmer socket. Keeping the PIC in the machine pin socket protects from bending the PIC pins. After a few bends they tend to break off. I usually insert a screwdriver blade between the machine pin and programmer socket to separate them, ( unplug the programmer first). PIX the Programming Software. The programming software I use is called PIX. The latest version, 1.13 can be found at: http://home5.swipnet.se/~w-53783 download the file pix113b.zip A file called PIX.CFG has to be edited to work with this programmer. Put in or remove semicolons to decide which options are active. Choose 'Port=Com4',(change to the COM port # you use). Use 'Programmer=Ludi' for the programmer. I could find no directions on how to use the programmer, but it seems pretty straight forward. Load the file using F3, (sometimes the command line seems to work also). Burn the program into the PIC with F9. My Setup: I might mention my setup and other programs I use. I work in DOS on a 486SX 20 computer. The text editor I use is SLED, (Sam's little editor), written in the '80's by Sam Willmont. Only 17K in size, it is free. ftp://ftp.funet.fi/pub/msdos/Simtel/editor download the file sled11.zip ,(31K) To get .HEX files I use MPASM from Microchip. It is free. If you stick to just the basics, it is pretty easy to use. get it at: http://www.microchip.com/10/Tools/Picmicro/code/MPASM/asm2300/index.htm Once you unzip the file, throw away all files except mpasm.exe and p16f84.inc. The manual can be found at: http://www.microchip.com/10/Tools/PICmicro/code/MPASM/33014g/index.htm But it is in computerese. Probably best to wait until you really need it. Beginning Programs: I am planning to do some simple LED flasher type programs, using the other half of the Radio Shack board to hold the circuit/s. If you drop a request at ockers@anl.gov, I'll send you a copy when I've got something.