PIC Series minimum system board

A. INTRODUCTION

        First time I learn the PIC series microcontroller is the PIC16F84 type. Then as time goes by the generation follow, PIC16F84A, then PIC16F628 and the last PIC16F628A type. Usually, I made a board for any purpose depends on the project, and never used a universal one. This time I will introduce the minimum system board to experiment with any project. This project board base on my experiment before and from any reference books and from the net. First time I programmed the chip using a board as a book bonus called El-Cheapo programmer, made by : Myke Predko. The link also can be found at rentron site. This board programmer used LPT printer parallel port interface. Using it is very-very nice. But the PIC chip must be put on and remove many times, besides that I only use 18 pin socket only. The other socket are useless. May be for the next project. Many computer design lately, already omitted this parallel interface, but for serial interface, it still there. This project board use serial interface.

B. SCHEMATIC

 

        As usual I start my design from my experience design before, and from the book that I learned. This schematic follow the schematic design by Martin Penev and others experiment out there. Interface using serial port only connected to 3 lines (5 lines infact) of PIC, ie: RB-6 as clock line, RB-7 as data line, and MCLR as Vpp line (this called ICSP programming). So another output are free from connecting. It took 2x6 headers to change over the jumpers when the state in programming mode or in running mode. Also add a push button to reset the board when using in running mode.

Here is the schematic board (pic_min_sys_S.sch, pic_min_sys_schematic.pdf)

D. PCB LAYOUT

        Because the circuitry do not much have devices, PCB for this minimum system board could be done with size 5.5x6.5 cm. Small enough for the experimenter board. The layout could be drawn using hand drawing also or you can use toner transfer paper. My own prototype made using a hand drawing.

Here are the PCB design and the PCB layout (pic_min_sys_P.pcb, pic_min_sys_layout.pdf, pic_min_sys_artwork.pdf)

E. PART LISTS

        Part list for this ISP minimum system board are :

   1. Resistors :
      R1 = 10 kOhm ............................................................ 1 pcs
      R2~R4 = 4.7 kOhm......................................................... 3 pcs

   2. Capasitors :
      C1,C2 = 22 pF ........................................................... 2 pcs
      C3 = 100 nf ............................................................. 1 pcs
      C4, C5 = 100 uF/16 V .................................................... 2 pcs

   3. Semiconductors :
      IC1 = PIC16F84/A (PIC Microcontroller) .................................. 1 pcs
      IC2 = 7805 (Variabel Regulator) ......................................... 1 pcs
      BD = 4 x 1N4007 (silicon diode) ......................................... 4 pcs

   4. Others :
      Optional IC socket for 18-pins .......................................... 1 pcs
      SIP connector, 8-pins ................................................... 2 pcs
      SIP connector, 5-pins (ISP cable) ....................................... 1 pcs
      SIP connector, 2-pins (power supply) .................................... 1 pcs
      Miniature push button  .................................................. 1 pcs
      Header 2x6 connector with jumpers ....................................... 1 pcs
      X'tal = 4 MHz ........................................................... 1 pcs
      DB-9 connector type (male) with housing ................................. 1 pcs
      Single layer PCB, size about 5.5cm x 6.5cm .............................. 1 pcs
      Transformer P=220V, S=9~12V/0.5A (Adaptor) .............................. 1 pcs

F. SOFTWARE

        Software available for this ICSP programming :

1. PIC-Prog software (175.155 Bytes), made by : Martin Penev, last update could be found at : PIC-Prog programmer site. But I think this never been update anymore.
    
2. IC-Prog software (582.447 Bytes), ver 1.06B (went I bump in to), made by : Bonny Gijzen. Very good software, thanks to him. It can also accepted LPT parallel version programmer, last update could be found at : IC-Prog programmer site.

G. ICSP CABLE

        ICSP cable is a self made type, using serial connection cable. The 3 resistors were put inside the connector, to simplyfied the PCB layout and to reduce the wiring option. By doing this, only 3 wires needed include 1 shielded for grounding. Besides that, every board can save these 3 resistors. The connection layout like this :

H. PROTOTYPE

        My prototype board has size of about (5.5 x 6.5) cm single side PCB. This is a small possible size that make it comfortable to use and making it using a hand drawing layout. All it takes are a small PCB with 14-pins PIC series microcontroller, a DIY parallel cable, and a wallwart small power supply type. PIC16F677/A type needs a bigger PCB layout, and the ISP connection pin also different with the others. Refer to the data book! All I/O connections using 8-pins SIP connectors. And also watch out the 6 jumpers in the center, each 3 jumpers correspond to write position or run position. Please mark it! It takes worth to experiment with this type of microcontroller anyway. The complete package can be obtain here.

I. APPLICATION

1. This is a sample program how to use this PIC microcontroller board. Simple program how to output a sound to a small speaker. Speaker tied to PA-4, and +5V - Vcc. Just to experiment with.