Picaxe Versabot User manual

The Versabot Manual
July 2009

Index
1. Getting Started
1.1 How this anual works
1.2 Breaking out your pieces
2. The Co ponents
2.1 The Motherboard
2.2 The Modules
2.3 The Microbric ‘Brics’
2.4 Connecting the Batteries
2.5 Joining Modules to your Motherboard using the Brics
2.6 The Download Adapter
3. Progra ing the Microcontroller on your Motherboard
3.1 Installing the software
3.2 Pin Nu bers
3.3 Making a LED flash
3.4 Adding a slide switch
3.5 Adding a buzzer
3.6 The push button
3.7 The otor – forwards/backward
3.8 Using bu p sensors
3.9 The infrared receiver
4. Building your Bu p Robot
4.1 What will it do?
4.2 Putting it together
4.3 Downloading the progra to drive your bu p robot
4.4 The code
5. Building your Re ote Control Robot
5.1 What will it do?
5.2 Putting it together
5.3 Preparing the Re ote Control
5.4 Downloading the progra
5.5 The code
6. What Now?
6.1 Cleaning up the edges
6.2 Variations
6.3 Go online

1. Getting Started
Finally! An electronics set that is really easy to build without sacrificing functionality! Welcome to
Versabot, the first solderless construction set made for electronics enthusiasts.
1.1 How this manual works
This manual will take you through the various components that you have received in your kit and how
to join them together. It will describe how to use your computer to program the individual parts of your
project. You will then be shown how to put a basic Bump Robot together, and how to download a
program to drive it and, finally, you will see a diagram of a completed Infrared controlled robot for you
to build, and download the code to drive it. In addition, you can go online to view Frequently Asked
Questions, New Possibilities for construction and New Code for programming as well as finding out
the latest news in Versabot electronics.
If you follow the manual through from start to finish, you will learn everything you need to know to
create the robots we have given you, as well as the knowledge and skills needed to build and program
unique robots of your own. Additional information about programming the PICAXE microcontroller
which acts as the 'brains' of your Versabot is included in the PICAXE Manuals accessible through the
Programming Editor and AXEpad Help menus.
1.2 Breaking out your pieces
Your kit comes with a range of pieces, shown below.
A number of your pieces will have arrived within PCBs (printed circuit
boards). You need to remove these pieces before you can start building
your robot. Most pieces can be pushed out with your thumbs, but if you
are having difficulties, use the end of your screwdriver to gently lever
them out.

2. The Co ponents
2.1 The Motherboard
The Motherboard contains the
'brains' of your robot. On it you will
find a PICAXE-28X2 chip, a 9-way
download connector for
programming your micro-controller,
an on/off slide switch, Pins (edge
contacts), a Power LED, and a
variety of components and
integrated circuits needed to
connect the circuits electronically
and mechanically.
2.2 The Modules
Along with your motherboard you have received a range of little circuit boards that hold
electromechanical devices. Each of these has a different function and when joined to the
motherboard at the pins, you can program them to perform their functions.
The modules consist of:
LED module This module contains an LED (light emitting diode) and the
circuitry to drive it. A LED is a tiny light, used, amongst other
things, to show that an electronic device is turned on.
Slide Switch
module
This module contains a small switch and the circuitry to drive
it. A switch allows us to turn an electronic device on, or
‘switch’ between two electronic functions.
Buzzer
module
This module contains a Buzzer and the circuitry to drive it.
The buzzer is able to make sounds and even play simple
tunes.
Button
module
This module contains a small push Button and the circuitry to
drive it. It can be used to start or stop an electronic function.
Motor module This module contains a small Motor and the circuitry to drive
it. The motor can be used to drive wheels forwards and
backwards.
Bump Sensor
module
This module contains a Bump Sensor and the circuitry to
drive it. A bump sensor can detect when it touches
something, such as bumping into an object.
Infrared
Receiver
module
This module contains an Infrared Receiver and the circuitry
to drive it. An infrared receiver can pick up a signal sent
using infrared light from a remote control device.
Labelled picture of
the Motherboard
(label parts listed
to the left)

2.3 The Microbric ‘Brics’
Microbric ‘Brics’ are tiny building blocks which can be used to hold the motherboard and modules
together. These tiny black pieces fit into holes along the edge of the motherboard and the modules
(and other parts) and, when screws are added, complete the circuit. You will need to assemble your
Brics before you can use them. To do this, fit 3 of the tiny nuts into each bric.
You can then use the Brics to attach the various modules (and other pieces) to the motherboard.
When connecting modules to the motherboard you need to make sure of a few things:
1. Make sure that the little red dot on the
edge of the module lines up exactly with
the little red dots on the edge of the
Motherboard (at the pins).
2. Make sure that you use all 3 screws and
do them up firmly (but not too tight).
3. Make sure that the Bric is the right way
around. It will only fit one way – you do
not need to force pieces together!
2. Connecting the Batteries
The motherboard is powered by batteries. You have been provided with four counter sunk screws that
are different to all of the others (they have a flat, instead of a rounded, head), and 4 nuts. Use these
to attach the holder to the underside of the motherboard, making sure that the gold battery contact
pads are aligned with the slots in the blue battery mounts and the wires from the battery holders. (See
the diagram below). The kit requires 6 AAA batteries. Put these in before flicking the switch to power
up your motherboard. Once it is turned on, check that the tiny red power LED is lit up – this will
indicate that you have put it together correctly. If it doesn’t light up, check that your batteries are all in
the right way and that they are pushed in firmly before rechecking your assembly.

2.5 Joining Modules to your Motherboard using the Brics
The modules are joined to the motherboard using Brics. You connect each module at a Pin. The pins
are written around the outside edge of the motherboard as P0, P1, P2 etc.
Let’s try connecting a module:
1. Find a LED module, from your module collection.
2. Line up the red dot on your LED module with the red dot on the Motherboard at P0 (Pin 0).
3. Now fit a Microbric into the holes on the edge of your LED module
NOTE: The tiny pins on the Bric fit into the holes
if you put the Bric in the wrong way, the bric will sit crooked, i.e.
However, if you turn it up the other way it will sit straight. i.e.
4. Fit the Bric into the holes at P0 on the motherboard.
5. Now screw in three screws firmly to complete the connection.
If you’ve done it correctly, your Module and Motherboard should look like this:
2.6 The Download Adapter
Your Versabot is provided with a 9-way to 3.5mm Jack socket adapter for downloading. If you are
using an AXE026 or AXE027 PICAXE download cable, or any PICAXE download cable which has a
3.5mm Jack plug, you will need to insert the 9-way to 3.5mm Jack adapter into the 9-way connector
on your motherboard. The download cable then plugs into the 3.5mm socket. The adapter board can
be left connected to your motherboard.
If using a CAB010 9 way M-F serial download cable this can be connected directly to the motherboard
download connector.

3. Progra ing the Microcontroller on your Motherboard
Your motherboard is fitted with a PICAXE-28X2 microcontroller that can hold a range of instructions to
drive various electronic components. The sets of instructions are called programs and writing the
instructions is called programming.
3.1 Installing the software
Programming computers or microcontrollers is done using programming languages. Computers which
are electronic can only understand the simplest of languages which is written in binary, that is 0s and
1s (or an electrical ON or OFF). As you can imagine, programming a computer entirely in 0s and 1s
would be very, very slow and tedious. So, higher level programming languages have been developed
to make this easier. There are hundreds of languages available, however our Microcontroller uses a
special programming language which has been written for it based on the BASIC programming
language. BASIC is easy to learn and remember.
To write programs, write programs, and to download them into the PICAXE microcontroller,
you need to install either the PICAXE Programming Editor or the cross-platform AXEpad
program.
3.2 Pin Numbers
The PICAXE motherboard has its connection pins labelled P0 to P15 but the PICAXE-28X2 uses a
different 'software terminology' than the 'hardware terminology'; a hardware connection to P2 is a
software connection to B.2, a hardware connection to P14 is a software connection to C.6 and so
forth.
This situation is very common in computer engineering where a general purpose programmable chip
is used with specific hardware and is very easy to deal with. All that is required is a table which maps
'hardware terminology' to 'software terminology' and you can go on using the hardware descriptions,
for example pin 1 (P1), which makes sense to you and the controlling software will understand what
you mean.
This table is implemented by using symbol commands and the complete set of pin mappings is as
follows:
symbol P0 = B.0 symbol P8 = C.0
symbol P1 = B.1 symbol P9 = C.1
symbol P2 = B.2 symbol P10 = C.2
symbol P3 = B.3 symbol P11 = C.3
symbol P4 = B.4 symbol P12 = C.4
symbol P5 = B.5 symbol P13 = C.5
symbol P6 = B.6 symbol P14 = C.6
symbol P7 = B.7 symbol P15 = C.7
There is another set of mappings for when the pins are used as inputs:
symbol IN0 = pinB.0 symbol IN8 = pinC.0
symbol IN1 = pinB.1 symbol IN9 = pinC.1
symbol IN2 = pinB.2 symbol IN10 = pinC.2
symbol IN3 = pinB.3 symbol IN11 = pinC.3
symbol IN4 = pinB.4 symbol IN12 = pinC.4
symbol IN5 = pinB.5 symbol IN13 = pinC.5
symbol IN6 = pinB.6 symbol IN14 = pinC.6
symbol IN7 = pinB.7 symbol IN15 = pinC.7
The details of the table and the mappings is not really important unless you want to get more deeply
involved in PICAXE programming generally. All you need to do is include the revelevent Symbol for
each pin your program uses at the top of the program. You can of course include the complete table of
Symbol definitions if you wish.
A complete list of PICAXE-28X2 mappings is included as program Picaxe28x2.bas on the CD-ROM
which may be cut and pasted into your programs as required.

3.3 Making an LED flash
Now let’s write our first program and then download it to your microcontroller.
1. Earlier we connected a LED module to pin 0 (P0) of the motherboard. If you haven’t done this
step, go to 2.5 Joining Modules to your Motherboard using Microbrics and follow the
instructions there.
2. Open the PICAXE Programming Editor or AXEpad progra .
3. When the Programming Editor or AXEpad opens you will be presented with a configuration
screen. If such a screen does not appear use the View/Option menu to display it.
4. Select the Mode panel and select the 20X2 option to match your motherboard PICAXE-28X2
microcontroller.
5. Select the Mode panel and select the serial port your download cable is connected to.
6. When you have finished click the OK button. You will be returned to the editing screen where
you can enter your program for the Versabot.
7. A good thing to do before writing code for a program is to draw a flow chart of how the
program will work. Here is an example of a flow chart that shows what our program will do:
START
Turn on LED
Keep on for
200
milliseconds
Turn off LED
Keep off for
200
milliseconds
8. Write the following program into the text window.
NOTE: It is important to type in exactly what is shown, because programming languages use
very specific code called syntax. If the syntax is incorrect, the software, and later the
hardware which is getting an interpreted version in binary, will not be able to read it. Note that
the space indents and Tab key alignments are used to make your program easier to read.
Writing after a single-quotes are comments and don’t affect the compiling or how the program
operates.
symbol P0 = B.0 ' Define Output P0
do ' Do the following ...
high P0 ' Set P0 high (5V)
pause 200 ' Keep P0 high for 200 s
low P0 ' Set P0 low (0V)
pause 200 ' Keep P0 low for 200 s
loop ' Repeat this loop forever
Some things to note about the program above:
•Notice that we have used space characters to indent parts of the program and the Tab
key to align things. This isn’t necessary, but makes it easier to read.

•Notice that the parts in grey after the single-quotes are descriptions of what the program
is doing. These also aren’t necessary, but help you to understand what your program is
doing, and to remember what it was doing when you come back to it in a year’s time (so
spelling mistakes don’t matter in here).
•Note that we are using P0 which is an output so specified P0 in the High and Low
commands, and provided the symbol definition required for P0 at the top of the program.
•We used a do / loop to keep the program ‘running round in circles’. The program will
continually repeat the commands within that loop until the Versabot is turned off or a new
program is downloaded to it.
9. Save your program to disk using the File/Save menu option and save your file as
LEDprogram.bas.
10. It is very important to save your programs. Although the Versabot will remember what program
was last downloaded to it, there is no way to read the program out of the Versabot later. If you
want to have a copy of your program you must save it to disk.
11. Make sure the download cable is securely connected to your computer and to the download
connector on your Versabot motherboard. Also, make sure your Versabot motherboard has
batteries and is switched on
12. Press the F4 key ( or use the PICAXE/Check Syntax menu option ) to check the syntax of
your program. If you have made any mistakes in typing your program the compiler will indicate
what they are’ click OK and correct any mistakes. When you have the program correct the
compiler will report “Syntax check successful!” and give an indication of how big your program
is, how much space is required to store that program.
13. Press the F5 key ( or use the PICAXE/Program menu option ) to download your program into
the PICAXE on your Versabot motherboard. A display screen will pop-up to show progress of
the program being downloaded.
14. Once the downloading has completed, you should see the light at pin 0 start to flash. You can
disconnect the serial cable and it will keep going. The program stays permanently in the
PICAXE memory, so you can turn the flashing LED on and off using the motherboard power
switch.

3. Adding a Slide Switch
1. Now let’s attach a slide switch and use it to control the speed of flashes on the LED.
2. Attach the Slide Switch module to P0 on the edge of your Micobric motherboard next to the
LED module (note the 0 and 1 written in gold on the module).
3. Again, let’s draw a flow diagram before we write the program. Here is one for the program we
will write.
START
Turn on LED
Keep on for
200
milliseconds
Turn off LED
Keep off for
200
milliseconds
Is switch
on?
Turn on LED
Keep on for
2000
milliseconds
Turn off LED
Keep off for
2000
milliseconds
Yes
No