Universal PIC 18F Board
Table of contents
Based on the experiences with the IPS Board I present here a design for a
multi purpose prototyping board for PIC 18F's.
Microchip offers a broad range of
microcontrollers (PIC's) for various applications. If you use such microcontrollers
to develop and prototype sollutions it can become cumbersome to design different
prototyping boards over and over again depending on the controller used. Thats
why I made the effort to design a Universal PIC Board UPB where a broad
range of different controllers (mostly of the 18F series) can be used. The
board offers RS232 (RX,TX including RTS,CTS), USB, a switch, a LED, ICSP, a reset and
power monitoring, I2C, external/USB power, power stabilization, connector
for alternate power (battery) and power switch and an expansion bus.
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Some may ask now 'Why another microcontroller board?'. And there are
more than one answer to this question:
- The presented board is capable to use different microcontroller types
like the 18F458, 18F4550 or the 18F877 to name just a few. They all
have nearly the same pin layout and also other types with comparable pinouts
should work with this board.
- RS232 support (including RTS/CTS support) as well as USB (depending on
the used controller) are available on the board.
- No usage of SMT parts. This makes it relatively easy to build the board
yourself. Nevertheless are the board dimensions very small (10 cm x 5,3 cm which
is only 1/3 Euro board).
- 5V power supply on the board can be realized using either a standard 78x05
linear regulator or some low drop regulator like the MAX603. External power
source is either a wall plug or via USB.
- Power monitoring, reset and brown-out detection is done by a DS1813 IC
- One LED and one switch is available on the board for free usage.
- In circuit serial programming (ICSP) of the microcontroller is supported
(if it supports it) via a 6 pin header. Using a DIL4 Dipswitch ICSP signals can be
disconnected from the rest of the board while programming.
- Via a 40pin bus on the bottom of the board, add on boards can be stacked
on top of the microcontroller board. 99% of the microcontrollers pins are
available on this bus.
- By using a 40pin adapter board (see Pictures) the microcontroller board
can be used in breadboard prototyping.
The schematic for the UPB is a classical microcontroller design. Besides the
power supply you will find the RS232 (suporting RTS/CTS) using the MAX232
(or a clone), a LED (connected to port B1), a switch (on port B0 which allows
interrups), a crystal, a reset and monitoring IC (DS1813) and the USB port.
There is nothing special to say about the PCB. This double sided PCB
is just 10 cm x 5,3 cm in size and contains no SMT parts. The board can be
customized bei using the jumpers J1-Jx or the copper jumpers Bx1-Bx11.
Bx jumpers can be opened by using a sharp knife and closed by using a
small solder bridge. The default board configuration is enabled RS232 including RTS/CTS,
I2C, the switch and the LED. USB is disabled by default.
Please note that some jumper configurations can damage your board
or microcontroller. PIC's share USB and I2C pins. So either you close Bx9-Bx10
and open Bx5-Bx6 ore vice versa. Also JP5 and JP6 are mutualy exclusive.
You can download a PDF File with the schematic and the PCB here.
If you dont have the Adobe Acrobat Reader installed on your machine you can find it here
||JP3||DIP-SW||ICSP Port B7||
||JP4||DIP-SW||ICSP Port B6||
||JP5||Jumper||use USB power||
||JP6||Jumper||use external power ||
||Bx1||SMT||RS232 CTS on Port C1||closed
||Bx2||SMT||RS232 RTS on Port C2||closed
||Bx3||SMT||RS232 RX on Port C7||closed
||Bx4||SMT||RS232 TX on Port C6||closed
||Bx5||SMT||I2C SCL PullUp R2 on VDD||closed
||Bx6||SMT||I2C SDA PullUp R3 on VDD||closed
||Bx7||SMT||Switch SW1 on Port B0||closed
||Bx8||SMT||LED D3 on Port B1||closed
||Bx9||SMT||USB D- on C5||open
||Bx10||SMT||USB D+ on Port C4||open
||Bx11||SMT||USB PullUp R4 on Port C32||open
|PWR1||Barrel||external power supply|
|PWR2||2Pin Jumper||Internal power supply (battery).
Disconnected by switch on PWR1 if external power used|
|PSW||2Pin Jumper||Connector for On/Off switch|
|RS232||RJ45||Serial interface (DTE). To connect to a PC use a
1:1 streight cable from RJ45 to SUB-D9.|
|ICSP||5 pin SIP||In Circuit Serial Programmin connector (ICSP) |
- Port B6
- Port B7
|BUS||40 pin header||expansion bus |
- C1 - RS232 CTS
- C3 - I2C SCL
- C2 - RS232 RTS
- C4 - I2C SDA
- C7 - RS232 RX
- C6 - RS232 TX
- C4 - I2C SDA
- C3 - I2C SCL
Notes & Comments
in the Press
||This paper can also be found in the german HAM Radio Magazine
Issue 07 / 2007, Page 748,
Title: "Universelles PIC-Board als Grundlage für SSTV-Modul"
If you have any comments or sugestions just drop me a line.