DATA SHEET

PicPatch ⁰⁸

Microcontroller Application Circuit Board

Data and Specifications

The multipurpose microcontroller interface.

Suitable for education and permanent control system applications.

Document A000084 Rev D PicPatch^™ Series Data Sheet

PIC Microcontroller Patch Board

PicPatch⁰⁸ microcontroller interface circuit board adaptable to suit different applications.

FEATURES TABLE 1

· Suited for Picaxe08 and Picaxe08M 8 pin
Pic microcontroller patch board.

· Power supply options with or without
5V voltage regulator.

· Power supply socket or screw terminal option.

· Serial programming viaRS232 serial
communication network.
Serial-Out pin common to port pin 0

· Reconfigurable networks on IO pin ports.

· 10 Way Expansion port connector.

Figure 1. PicPatch⁰⁸ Printed Circuit Board (PCB) Layout

Applications

Suitable for general purpose type control systems with sensor inputs, output driver devices and serial
communication to a remote computer programming and monitoring station.

Ideal for electronic education to demonstrate the fundamentals of basic software programming,
electronic sensor interfacing and output driver devices such as an LED, lamp, relay, solenoid,
small electric motor, Piezo beeper, magnetic beeper, etc.

FIGURE 2. Microcontroller Pin Configuration

DESCRIPTION

The PicPatch⁰⁸ is a small 8 pin microcontroller circuit board that can be easily adapted and programmed for low
budget control systems and remote monitoring applications. Basic applications may include robotics,
musical door bell, intruder alarm system, weather monitoring, irrigation and environmental process control.
Interfacing sensors and output control devices to the Pic Microcontroller chip is both simple and quick to
assemble. “Pic” is a trademark of Microchip Techmologies.

The PicPatch⁰⁸ has provision on the circuit board for circuitry to be assembled for each microprocessor port pin
which provides the flexibility to interface and configure circuitry suitable for various sensors and output devices.
This interface circuitry network can also utilise single inline (SIL) component sockets which will provide quick
component insertion and replacement.
Should the SIL sockets be used a soldering iron is only required initially to assemble the circuit board.
This easy interfacing provides a valuable education tool for teaching basic electronics and developing a custom
made multipurpose micro control system that can be reprogrammed for different applications.

Utilising the Picaxe 08 or Picaxe 08M microcontroller chip, which is a trade mark of Revolution Education,
their Basic Editor program provides the user with a complete microcontroller system that is very quick to learn
and simple to develop. Refer to last page for contact details.

Figure 3. PicPatch⁰⁸Circuit Diagram

OPERATION

The PicPatch⁰⁸ has four INPUT / OUTPUT port pins and serial communication, Transmit “SERIAL
OUT” and Receive “SERIAL IN” port pins for communication to the Personal Computer (PC).
Port pin 0 is the same port as the Serial-Out pin, if a beeper is connected to PIN 0 a squeal sound will
be heard as information is sent from the PIC microcontroller to the PC.
The PicPatch⁰⁸ circuit diagram Figure 3 and the circuit illustrations for each port pin (See Fig. 4 to 8)
will be used as a basic guide for configuring the interface circuitry.

Refer to the Revolution Education and Basic editor program manual for details on developing
software programs suitable for the PicPatch⁰⁸.

Remember to configure the port pins according to the application examples illustrated in the manual.
Failure to do so may cause undesirable side effects or possible component damage.

Component List Table 2 Main components list

POWER SUPPLY NOTES

4.5V Battery operation: (3x AA Battery pack)

For 5V Regulated Power Packs and 4.5V Battery supplies place a wire jumper to link pins 1 & 3 of
IC2, Refer to dotted line on Figure 1.

Check capacitor C4 pin alignment is correct for (+) and (-) polarity.

Placing C4 is optional for battery operation but we recommend fitting C4 for all motor and relay
applications. For larger transient current loads in excess of 200mA, increase the capacitor value by
100uF for each 100mA increase in loading.

12V to 24Vdc Power pack or battery operation:

For supply voltage in excess of 5.5Vdc fit IC2 the 5V Voltage Regulator.
The maximum load is 50mA without a heat sink fitted and 100mA with a heat sink fitted.

If the load current on the +5V rail exceeds 50mA the regulator will get hot and may shut down to
protect itself from over heating. If the regulator exceeds 70^oC fit an “L” shaped aluminium heatsink
between the regulator tab and circuit board to improve heat dissipation. Use a M3 machine screw,
spring washer and M3 nut to fix the heatsink and regulator to the circuit board.

PORT PIN CONFIGURATION

The PicPatch⁰⁸ circuit board is designed specially to use the Picaxe 08 or Picaxe 08M microcontroller
chips, which is a trade mark of Revolution Education. Pic is a trade mark of Microchip Technologies
series of 8 pin Pic Microcontrollers. The Picaxe Editor Program, download from the Revolution
Education Website, has examples of how to program the microcontroller chip and various circuit
configurations that can be implemented on the PicPatch circuit board.

Information provided by KEI Ltd on projects using PicPatch⁰⁸ will use this data sheet as a reference
guide to describe and illustrate how to connect each configuration of components suited to the
application.

The components on the circuit board are numbered to help identify the Pin naming associated with each
port pin on the microcontroller. The resistors on the circuit diagram in Figure 2 use the port pin
number, however in the following circuit examples we will use the letter “n” as a substitute with the
port pin number. E.g. Rna Rnb Rnc Rnd. Refer to Figures 1, 3 and 4 to 8.

Rna – These resistors connect directly between the micro pin and the associated terminal connector
            centre screw terminal. If the micro pin is configured as an input this resistor is fitted in
            conjunction with a filter capacitor fitted across the micro pin to 0V. This provides filtering of
            unwanted electrical noise and improves immunity from Electrostatic Discharge (ESD).
            If the micro pin is configured as an output this resistor provides current limiting such as
            driving an Light Emitting Diode LED, or impedance protection to guard the micro pin from
            over-current from potential short circuits to neighbouring supply rails 0V,+5V,+V etc.

Rnb - When the micro pin is configured as an output to drive a Transistor these resistors, which
connect between the micro pin and middle pin of the transistor SIL socket, are used to limit the
base current to a transistor. The centre pin or base “B” pin for BC546, BC337 Transistors.

Rnc - These resistors connect directly between the micro pin and the 0V supply rail.
This position is used for a “Pull-Down” resistor or input filter capacitor position.

Rnd - These resistors connect directly between the micro and the +5Vdc supply rail.
This position is used for a “Pull-Up” resistor.

Port pins 0 and pin 3 do not have some resistors as listed, as these pins have limited functions with
some Pic microcontrollers.

The following diagrams illustrate typical port pin circuit configurations.

FIGURE 4. Port pin 1, 2 & 4 circuit diagram (Output / Input / Analogue Input)

FIGURE 5. Port pin 0 circuit diagram (Serial Out / Output / Infraout)

FIGURE 6. Port pin 3 circuit diagram (Input / Infrain)

FIGURE 7. Transistor driver circuit diagram ( Pins 0,1,2,4 ).

FIGURE 8. LED circuit diagram ( Pins 0,1,2,4 ).

TABLE 3. Quick Reference Electrical Specifications

Important – Do not get confused with IC1 pin number and the pin Name used in Software.

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