Getting to Know Your MicRoCon

MicRoCon – Micro Robotics Controller for Raspberry Pi


This is the baby sister to our full-featured PiRoCon controller board. It still features two bi-directional motor controllers, a 5V regulator for the Raspberry Pi as well as general purpose IO connectors, 5V servo outputs and a 4-pin Ultrasonic input.

Motors A & B

  • Motor A: Pins 24, 26 (GPIO: CE0 and CE1)
  • Motor B: Pins 19, 21 (GPIO: MOSI, MISO)
  • Permanently enabled
  • Use either pin for each motor with PWM
  • Remember to invert the PWM duty cycle when reversing
  • Motors are driven via an L293D H-Bridge chip from the input voltage at the 2-pin terminal (not from the regulated 5V supply)


 GPIO Connections

  • These are NOT level-shifted and only work with 3.3V devices. Do not connect a 5V input
  • Each GPIO pin has an asdsociated Ground and 3.3V pin so can connect 3-pin sensors directly
  • Pin 7 (GPIO: 04)
  • Pin 11 (GPIO: 17)
  • Pin 12 (GPIO: 18)
  • Pin 13 (GPIO: 27)



  • These 2 sets of 3 pins provide outputs to drive 5V servos
  • The signals are not level-shifted but all servos I have tried work happily with a 3.3V input signal
  • Servo 1: Pin 18 (GPIO 22)
  • Servo 2: Pin 22 (GPIO 25)


Ultrasonic Input

  • These four pins allow an HC-SR04 4-pin ultrasonic sensor to be connected directly
  • This uses a resistor network to allow the sensor to use only a single GPIO pin, which is shared between Ping/Trig and Echo
  • Output a pulse using the pin in output mode
  • Then switch to input mode to await the response
  • This is connected to Pin 8 (GPIO: Txd)



  • This uses an L4040V5 linear low dropout regulator
  • The input voltage can go as low as 6V and the output will remain at 5V
  • The higher the input voltage, the hotter the regulator will get in use
  • The motors do not use the regulated voltage so will have no effect on the temperature of the regulator


I2C Female Header

  • Allows easy access to the I2C signals SCL and SDA
  • Also provides 0V, 3.3V and 5V connections
  • Same pinout as used on the PiRoCon expansion header so all expansion boards for the PiRoCon can also be fitted to the MicRoCon – ADC, 16-channel PWM available right now.
  • You can use the 4tronix IP Display dongle directly into this header.


Return to MicRoCon Home

Using the PiDie Raspberry Pi Addon Board


There are 9 LEDs arranged in a 3×3 matrix:

  • 1, 2, 3 down left side (Red, Yellow, Green – ideal for use as traffic lights)
  • 4 in centre (Green)
  • 5, 6, 7 down right side (Yellow, White, Blue)

These 7 LEDs then form the dots on a dice. The matrix is completed with LED8 (Red – top centre) and LED9 (White – bottom centre)

1  8  5
2  4  6
3  9  7

The Buttons are Red (top left), Green (bottom left), Yellow (top right), Blue (bottom right) and the colours match the colours of the LEDs in the same corners. Ideal for use in the Simon game,


Pin Connections

These refer to the physical pin numbers on the GPIO header. If using gpio module in python, then set the mode to “board”.


  • Led1: 7
  • Led2: 11
  • Led3: 12
  • Led4: 13
  • Led5: 15
  • Led6: 16
  • Led7: 18
  • Led8: 22
  • Led9: 8


  • Red: 21
  • Green: 19
  • Yellow: 24
  • Blue: 26


Use in ScratchGPIO

Download the excellent ScratchGPIO by Simon Walters from here.

  • Create a variable called “AddOn”. In the green flag black, set the variable to “PiDie”
  • The LEDs are named Led1 to Led9
  • To switch a LED on or off, you can send a broadcast message, or use variables.
  • Using broadcasts. Create a new message specifying what you want to happen. The syntax is “Led1On” or “Led1Off”. Change the number to select a different LED:
  • Using variables. You should create variables called Led1 to Led9. You can use the variable setting blocks to switch them on or off:
  • You can also set them all on or all off with a broadcast “AllOff” or “AllOn”


Use in Python

  • Import the GPIO library: import RPi.GPIO as GPIO
  • Set the GPIO mode to board: GPIO.setmode(GPIO.BOARD)
  • Set the LED pins as outputs: GPIO.setup(7, GPIO.OUT) // 7 is the for LED1. You need to do this for each LED, or use lists, etc
  • Set the Button pins as inputs: GPIO.setup(21, GPIO.IN, pull_up_down=GPIO.PUD_UP) // 21 is the for the Red button. You need to do this for each button, or use lists, etc
  • Note that in the line above we are using the internal pullup resistors. This is mandatory for the buttons to work.
  • You can then set an LED On or Off by setting the output to 0 (ON) or 1 (OFF): GPIO.output(7, 0)
  • You can check if a button is pressed with an IF statement: if GPIO.input(21):

Soldering the 4tronix PiDie Kit

Click on any image to enlarge it

Check you have all the parts


  • Printed circuit board (PCB)
  • 1 x Diode (not shown above)
  • 4 x switches
  • 2 x resistor networks
  • 4 x capacitors 100nF
  • 12 x LEDs (2 x red, 2 x yellow, 2 x green, 2 x white, 1 x blue)
  • 1 x GPIO 26-waye female header
  • Mounting assembly (10mm hex spacer, 2 x M3 screws, 1mm washer)

Starting Soldering

If you haven’t soldered before, you might want to check out this instructable. I find that the following order of soldering works best, starting with the lowest profile components and moving to the highest. This allows me to place the components through the holes in the PCB, then turn the PCB over onto the desk surface and gravity will hold the components in place. You can also use Blutack to hold the components in place while you solder


1. Add the diode

The black diode has a white/grey stripe on one end. this MUST match the marking on the PCB as shown in the photo below in the position D1



2. Add the 100nF Capacitors C1, C2, C3, C4

These are small, yellow and marked 104. It doesn’t matter which way round they are put in, but it is neatest if they point the same way. They fit into positions marked C1, C2, C3 and C4



3. Add in the resistor networks RN1, RN2

These must be soldered in the correct way round. Double check before soldering. The writing needs to be closest to the GPIO header location, with the black dot (for pin 1) next to the end marked on the PCB with a small ‘1’

pd04 pd03


4. Solder the switches

These may already be clipped into position when you receive the kit, because that protects them during shipping. However, they will not be soldered so you need to do that for them to work. It doesn’t matter which way round they go – they can fit in 2 positions.



5. Add in the LEDs

The LEDs must fit in the correct way round or they will not work. The long legs on each diode must go into the hole next to the + mark on the PCB. All LEDs are oriented the same way – so if you get one right, then all should be right.

Step04 led01 pd06


6. Solder the GPIO Header

This must be placed on the opposite side of the board to all other components. It is extremely difficult to remove them if soldered incorrectly, so please double check before soldering



7. Add the Caps for the switches

These can go any way round, Just carefully push on so they click in place



8. Screw on the spacer

Fit an M3 screw through the hole in the board, then add the 1mm washer, then screw on the 10mm hex spacer. You can then push the board onto the Pi and the spacer will keep the board stable when the switches are pressed. You can screw it onto the Pi if you like, or simply let it rest. Please don’t use this spacer if using a Rev A Pi (without the mounting holes) as there are components in that place which can be damaged,

4tronix Initio Home Page

About 4tronix Initio


The Initio 4WD robot platform has been specially designed here in the UK to work easily with Arduino and Raspberry Pi controllers. Supporting products include motor driver boards, sensor shields, sensors, pan-tilt mechanisms and more. We also have a range of kits available for both Arduino and Raspberry Pi platforms

Outline Specification

  • An extremely flexible and easy to use 4WD Robot platform designed by 4tronix especially for Raspberry Pi and Arduino
  • Injection moulded from tough ABS
  • Built-in powerful 170-size motors and high-quality gearboxes
  • Arduino (UNO, Mega2560 or Leonardo) and Raspberry Pi mount directly onto the base-plate
  • 6-cell battery box with switch, charging socket, wiring for motor driver and Arduino already in place
  • Built-in speed encoders on each side with electronics already fitted
  • Each wheel can be individually decoupled from the gearbox – run as 1WD, 2WD or 3WD if you want!
  • Fixings for stepper motors (28BYJ-48 as found in our shop – not included) so you can replace the DC Motors with stepper motors for greater accuracy
  • No soldering or gluing required – simply screw together and plug in the wires (of course you can add things we haven’t thought of and they may need soldering)
  • The main chassis is delivered ready-built and all wires connected
  • All you need to do is add in the control boards and screw on the top plate
  • Mounting plates included for IR obstacle sensors and Line sensors
  • Loads of extra mountings for additional boards included


Purchasing Initio

4tronix Initio Assembly


Online Guides:

Other Assembly Information

Downloadable PDF Guides:



Motors Not Turning

  • For Raspberry Pi, ensure you are using correct software. Use the software in “robohat” folder if using RoboHat, or in “initio” folder if using Pirocon
  • Batteries. You must use good quality rechargeable batteries, not alkaline. We strongly recommend Energizer Extreme 2300mAH




4tronix Initio Programming Examples


Arduino examples are found in our Arduino support site

  • initio_01 simply moves initio back and forwards and spins
  • initio_02 uses PWM to control the speed and create smooth turns
  • initio_03 shows how to use the speed sensors to move accurate distances
  • EncoderTest01 tests the operation of both wheel sensors. Use the switches on the top of the gearbox to disengage the wheels from the gears, then turn the wheels by hand to see the results on the serial monitor
  • initio_04 uses the obstacle sensors to avoid obstacles
  • initio_05 adds a light-follower function using LDRs mounted on the Pan/Tilt (Connect one end of each LDR to 0V, the other ends to A0..A3)
  • initio_06 uses the line sensors to follow a black line and stop when it reaches a cross-roads
  • initio_07 uses the ultrasonic sensor mounted on the Pan/Tilt to avoid obstacles and travel in the direction of most space



Raspberry Pi ScratchGPIO examples are found in our GitHub

  •    Allows control of the motors using arrow keys (ScratchGPIO)
  •    Allows moving the pan/tilt assembly using arrow keys (ScratchGPIO)
  •    Shows operation of the UltraSonic sensor (ScartchGPIO)
  •    Uses the ultrasonic sensor on a Pan/Tilt assembly to follow (ScratchGPIO)
  •    Uses IR obstacle sensors and motors to avoid objects (ScratchGPIO)
  •    Uses line sensors, obstacles sensors and motors (ScartchGPIO)
  • Also see this post for using the wheel sensors with Raspberry Pi and the PiRoCon


Raspberry Pi Python examples can be downloaded from an LXterminal session and connected to the internet, type in or copy and paste:.

wget -O

Then type in:


You will then have a number of python examples in the robohat folder to try. Run them with:

sudo python
  •  use the arrow keys to move forwards and backwards, spin left or spin right. Space to stop. Use . and , to increase or decrease speed
  • Prints the distance in centimetres from the ultrasonic sensor, once every second
  • Prints the state of the IR line and obstacles sensors, every time the state changes.
  •  use the arrow keys to pan and tilt

NB. If using the older Pirocon controller the replace robohat with initio throughout the above.


Yes, you can now program the Initio for Raspberry Pi directly in C. What’s more, it works seamlessly with both the Pirocon and the RoboHat control boards so your program can work on either without being changed

Visit this link to find out more about this which was written by Dr Raimund Kirner at the University of Hertfordshire




PiRoCon Robotics Controller – Links

Links for Various Resources for the 4tronix PiRoCon



If you are experiencing low power to the motors when using the DC Jack input, it is very likely that you have not set the power selection jumper correctly to the right as shown below:



New: PiRoCon v2 released



  • Pins 15 & 16 (Broadcom GPIOs 22 and 23) are swapped from what is shown on the silk screen
  • Pin 11 is shown as GPIO 07 on the jumper bank, instead of GPIO 17


Getting to Know Your PiRoCon

Tour of PiRoCon

In this post we will take a tour around the PiRoCon v2 board and see how all the various elements operate and can be configured



Power Supply


  • The DC Jack (bottom left) is the input connection for your battery voltage. The voltage should be between 7V and 12V and will need to be able to supply at least 2A. This is a 2.1mm DC Jack with positive centre pin. Below about 6.5V, the regulator will not be able to output the 5V required for the Raspberry Pi to work. Above 12V, the regulator will probably get too hot.
  • The voltage regulator (lower left side) is used to convert the input voltage to 5V as required by the Raspberry Pi. For version 2 of PiRoCon we use a switching regulator which barely gets warm even at higher input voltages and no heatsink is required. Note that the motors are not powered from the regulated power supply


Motor Drivers


  • The terminals for two DC motors are at the top right of the board. Motor A on the left and Motor B on the right
  • Both terminals are wired the same way (left to right) so the same inputs would drive the motors in the same direction. If you use one motor for a left side drive on a robot and the other for a right side drive, then you should swap the wiring for the second motor. For instance, using the example programs on the Initio, you should wire Red-Black-Black-Red
  • The motor terminals are driven directly from the output of the H-Bridge driver chip L293DD (shown just below the motor terminals)
  • The 4 GPIO pins used to drive the chip are the SPI pins CE0, CE1, MISO and MOSI. These are connected via solder jumpers (to left of the L293D) – these are pins 19, 21, 24, 26
  • If you want to use other pins to drive the motors, then you should cut these these connections and wire your own connections to the required positions
  • Each motor has an enable pin which by default is connected directly to 5V using the jumpers just above the solder jumpers and below the 8×3 header block. For some purposes it is better to use the enable pins for the PWM signal, so that you can use the 4 control pins to purely control the direction. If you want to do that, then you should remove the jumpers and wire the enable pins to a PWM source (eg. an Adafruit 16-channel PWM board plugged into the PiRoCon expansion sockets)
  • In the bottom right of the photo above is a separate 2-pin terminal for external power. If you don’t want to drive the motors from the incoming battery voltage on the DC jack, you can move the selection jumper (just above the 2-pin terminal) and provide your motor voltage directly to the 2-pin terminal. This voltage can be from 5V-15V DC – ensure you connect it the correct way round. Note that this 2-pin terminal does NOT power the 5V regulator, only the motors.
  • For normal operation using the DC jack input. ensure the jumper is placed to the right side, or no power will get to the motors


5V GPIO Connector (8×3 rows)


  • NOTE: The Ground pin for the 8×3 block of GPIO pins is at the lower side for v2 PiRoCon (upper side for v1), so be careful when wiring
  • There are 8 unallocated GPIO pins available and these are brought out to a bank of 8×3 male headers
  • The headers are at 0.1″ pitch so you can connect standard 3-pin 5V sensors or servos etc. directly to them
  • Each signal is separately fed through a bidirectional level converter so can safely be used to input or output at 5V
  • Each signal is labelled with an x-number (on the jumper block) and a #-number
    • x refers to the physical pin number on the GPIO connector. So the first signal on the left is x07 which is pin 7 on the GPIO connector
    • # refers to the GPIO number itself. So the first signal (x07) is GPIO#04
  • Each signal can be disconnected from the GPIO header to the Raspberry Pi, by removing the relevant 2-pin jumper (shown top left)
    • If you remove the jumper, then the related signal in the bank of 8×3 is no longer in use
    • You should then connect a 3.3v max input or output to the signal pin where the jumper was
    • This allows the use of 3.3V sensors (eg. the wheels sensors on the Initio)
    • There is a 2-pin header (top left) which has two 3.3V connections, intended for powering 3.3V sensors
  1. #04 – x07
  2. #17 – x11
  3. #18 – x12
  4. #27 – x13
  5. #23 – x16 NB. Labelled incorrectly on board as #22
  6. #22 – x15 NB. Labelled incorrectly on board as #23
  7. #24 – x18
  8. #25 – x22

Please note, as described above, there is a layout mistake on the PCB which results in pins 15 and 16 (GPIO numbers 22 and 23) being swapped. So ensure that you plug into the correct connection for your application

Ultrasonic Sensor


  • There is a group of 4 pins (shown above at top right) that are designed to add an HC-SR04 ultrasonic sensor directly to
  • From the left, these are 5V, Trig, Echo, Gnd and match the ordering of the pins on the sensor
  • There are 3 resistors which process the signals so that both Trigger and Echo can use the same GPIO pin on the Raspberry Pi and also that this is 3.3V safe
  • The jumper (just below and left of the ultrasonic 4-pin connector) can be used to select either TXD (pin 8) or SCLK (pin 23)
  • If you want to use a completely different pin, simply remove the jumper completely and connect the pin you want to use to the centre pin of these 3


SPI Connector


This 8-pin female header allows you to connect the SPI signals. Note however that these are also used for motor controls by default, so you may need to attach the motors to different pins if you want to use SPI. Alternatively, simply don’t connect the motors when using SPI.

  1. 5V
  2. 3.3V
  3. CE1
  4. CE0
  5. SCLK
  6. MISO
  7. MOSI
  8. GND


I2C Connector


This 6-pin female header allows you to connect additional modules using the I2C connections. These are not used on the PiRoCon itself, although the expansion boards (see below) can use them. This connector also has the UART RXD/TXD pins on together with Gnd and 3.3V

  1. Gnd
  2. RXD
  3. TXD
  4. SDA
  5. SCL
  6. 3.3V


Expansion Board Sockets


There are two 6-pin expansions sockets that use I2C connections to add functionality to the PiRoCon. Expansion boards available right now are:

  • 4-channel analog input (ADC) with single channel analog output (DAC) from 4tronix



  • 16-channel PWM or servo driver from Adafruit



If you use stacking headers for the 6-pin connectors, and right-angle headers for the signals on the boards, you can stack these I2C expansion boards as much as you like. Here are both the above expansion boards fitted:



MicRoCon mini Robotics Controller Board for Raspberry Pi – Assembling

MicRoCon Robotics Controller Kit



Click on any image to enlarge.

The MicRoCon is the baby sister to the more powerful PiRoCon board, but incorporates many of the same features and in fact can use exactly the same code for programming as the pins it shares are the same. Here is a brief comparison table between the controllers:


Check you Have all the Parts


  • Printed Circuit Board (PCB) with the 5V regulator already fitted
  • L293D H-Bridge driver chip
  • 470uF capacitors x 2
  • 100uH Inductor
  • Diode
  • 2-pin Screw Terminals x 3
  • 2K2 resistors x 2 (coded Red-Red-Red-Gold)
  • 1K resistor (coded Brown-Black-Red-Gold)
  • 4×3 male header blocks x2 (one has 2 pins removed) [alternatively we may ship with 4 off 2×3 male header blocks depending on availability]
  • 6-pin female header
  • 26-pin GPIO header
  • Fixing hardware – M3 screw, M3 nut
  • Heatsink
  • Rubber “foot”


Starting Soldering

If you haven’t soldered before, you might want to check out this instructable. I find that the following order of soldering works best, starting with the lowest profile components and moving to the highest. This allows me to place the components through the holes in the PCB, then turn the PCB over onto the desk surface and gravity will hold the components in place. You can also use Blutack to hold the components in place while you solder


1. Add the Resistors

The PCB is labelled with the resistor values. 2K2 resistors are marked by Red-Red-Red-Gold bands, and the 1K resistors is Brown-Black-Red-Gold. It is neatest to ensure that all resistors point the same way. Make sure you snip off the leads on the back after soldering.


2. Add the Diode

The PCB is labelled with the resistor values. 2K2 resistors are marked by Red-Red-Red-Gold bands, and the 1K resistors is Brown-Black-Red-Gold. It is neatest to ensure that all resistors point the same way. Make sure you snip off the leads on the back after soldering.


3. Add the L293D chip

Make sure that pin 1, marked by the little black round indentation and the U-shaped cutout of the chip, is at the edge of the board as shown below.

Note: This chip may already be inserted in the board for protection during transport – but it won’t be soldered.


4. Add the screw terminals

These terminals are used to connect the motors and also to supply external power to the board for the regulator and the motor driver.

Solder all the terminals onto the PCB facing outwards



5. Add the Male Header blocks

These 4×3 header blocks are slightly different from each other, as one has 2 pins removed from it. Make sure you put them into the correct place as they would be difficult to remove if placed incorrectly (of course the block with all its pins won’t fit into the other position, but vice versa is possible).




7. Add the 6-Pin Female Header

This header brings out the I2C pins from the Raspberry Pi together with 5V, 3.3V and Ground. This is our standard layout and the 4tronix IP Display dongle will fit directly in here.



8. Add the 470uF Capacitors C1 and C2

These are polarised and must be placed the correct way or magic smoke will appear. The long lead is positive and should be placed in the hole marked with a ‘+’ on the PCB. The casing has a grey band with down arrows next to the negative pin – the grey band should be facing the GPIO connector as shown below. Cut off the legs on the underside after soldering



9. Solder the GPIO Connector to Bottom of PCB

Your kit may be provided with a choice of standard or extended header – select the one you want to use. The other is not required. Make sure you solder this to the correct side of the board!




11. Finally Fit the Pillar and rubber foot, then fit onto the Raspberry Pi

mcStep12a   mcStep13a  mcStep14a  mcStep15a


Return to MicRoCon Home


Assembling and Using PiRingo

Purchase 4tronix PiRingo >here<

Parts Included

  • Blank PCB
  • 12 LEDs – various colours depending on design chosen
  • 3 resistor networks (5-pin)
  • 2 miniature tact switches (2-pin)
  • 2 capacitors (100nF) – optional
  • GPIO connector header
  • 11mm hex spacer and screws (10mm metal spacer plus 1mm washer)


Tools Required

  • Soldering iron
  • Side cutters (could use nail clippers if necessary)


Soldering Sequence

  1. First add the 3 resistor networks to positions RN1, RN2 and RN3 as shown below. These are black, labelled A221J and have a white dot near one end. The white dot must be at the pin marked with a ‘1’ and next to the component name (ie. RN1, RN2 and RN3)
  2. Note that an unused hole is left at the other end (this hole is to allow different components to be used if 5-pin networks become unavailable for any reason)
  3. Then add the 2 switches, one either side in positions SW1 and SW2. It doesn’t matter which way round these are placed
  4. If you are concerned about switch bounce you can add the two 100nF capacitors, C1 and C2. As they are included with the kit and not difficult to add, then we recommend that they are added. it doesn’t matter which way round they are fitted
  5. Then add the LEDs. These are all the same way round with the long lead next to the ‘+’ on the PCB. The LEDs will not work if they are connected the wrong way round, but no damage will occur. You can also tell the negative lead by looking inside the LED itself. The lead with the large triangular plate is the negative lead.
  6. Finally add the GPIO connector. This must be added to the opposite side of the board!


Using the PiRingo

  1. Download example Python codes from our GitHub
  2. You can also view the PCB design schematic at the same location
  3. Download and install the Scratch GPIO v4 from @cymplecy
  4. Current example Python programs are:
    1. – switches all LEDs on
    2. – switches all LEDs off
    3. – goes through a sequence of flashing and chasing patterns. These are all coded as separate functions, so you can easily change to any sequence you require
    4. – moves a single LED under command of the two switches. See who can press the  switches faster
    5. – creates a range of LEDs for the fastest switch presser – when the bar reaches the other side, the winner is declared with flashing lights!
  5. Current example Scratch GPIO programs are:
    1. Traffic lights simulation


Pin Definitions

The Pin numbers below refer to the physical pin numbers on the GPIO header. To use these pin numbers in Python, be sure to set the GPIO mode as “Board” as shown here:

All LEDs and switches are Active Low. So set an LED to 0 to turn it on, set to 1 to turn it off. Switches are 0 if pressed, 1 if not pressed

  • LED1 – pin 7
  • LED2 – pin 11
  • LED3 – pin 12
  • LED4 – pin 13
  • LED5 – pin 15
  • LED6 – pin 16
  • LED7 – pin 18
  • LED8 – pin 22
  • LED9 – pin24
  • LED10 – pin26
  • LED11 – pin 8
  • LED12 – pin 10
  • Switch 1 – pin 19
  • Switch2 – pin 21


Assembling Initio Robot using PiRoCon Controller

build01Initio in box and philips head Screwdrivers

These are all the tools you will need to complete the robot.

You may also want a pair of side-cutters to remove some of the extra mounting







Hbuild02ere’s what is in the box

Main chassis with motors, gearbox, battery box and wiring

Top plate

Bag of plastic parts: pillars, standoffs, offset standoffs

Various screws

4 wheels with “SuperGrip” treads



build03Step 1: Add the vertical pillars by screwing from underneath with the wide-head screws

It’s a good idea to add the mounts for the obstacle sensors and line sensors if you have them.






Step 2: Screw the top plate on using the remaining 4 wide-head screws.


The pillars marked with red circle are where the Model A/B Pi will mount

For a Model A/B you will need to snip off some of the unused pillars so they don’t touch components on the Pi, but this is not necessary for a B+ if you use the adaptor plate

Feed the wires for the motors up to the top




Step 3: For Model A or Model B Sbuild05crew the Pi into position with 2 screws.

If you have used the correct mountings then the Pi will have the SD card slot above the On/Off switch

For most purposes you can use a Model A as easily as a Model B.







Step 3: For Model B+

Use the included adaptor plate (Only for Initio shipments after 20th September 2014). You should screw the 4, 10mm pillars into the plate using 4 of the screws provided, then screw the plate to the Initio using the same holes as for a ModelA/B. There is no need to snip any mountings off in this case.


Alternatively (also for shipments before 20th September 2014) you can use 1 fixed mounting for the top right hole, and use one of the small offset mounts for the bottom left hole. You will need to snip of some of the mountings for this arrangement.





build06Step 4: Now attached the PiRoCon by pushing carefully onto the GPIO header. If using a Model B+ with Pirocon v1 then you will need to attach the extended header (provided) to the PiRoCon before plugging into the Pi. You should also use the 12mm male-female hex pillar to extend the pillar length to match. For Pirocon v2 it will fit directly to the Model B+. All other instructions remain the same

Ensure that all pins are plugged in correctly as damage will ensue if you plug it in wrongly

Use the 10mm hex spacer and 1mm washer provided to allow the PiRoCon to rest securely on top of the Pi’s mounting screw

An alternative when using a Raspberry Pi Model A/B is to use a Male-Female hex spacer. Screw the male end through the Pi and into the mounting pillar (you will need to drill this to 3mm). Then you can fit the 1mm nylon washer and screw the PiRoCon onto the pillar. It is all mounted firmly and can only be removed with a screwdriver.



build07Step 5: We can now attach the motor wires to the PiRoCon terminals

Motor A for the left motor and Motor B for the right motor

The wires are colour-coded so that we know which way is forwards. The correct order is Red-Black-Black-Red as shown below. (note that “black” is actually a “black and red” wire)


This can be tested with the MotorTest script at this point if you like.



build09Step 6: Attach the Pan/Tilt assembly

Head on over to >here< for the assembly instructions if you haven’t already built the pan/tilt assembly

The ultrasonic sensor is attached to the clip-on pan/tilt mount by the included small saddle clamp and small screws. In fact the saddle clamp is designed to clamp the 30cm female-female cables, enabling the sensor to be plugged and unplugged at will. You will have received the correct number of wires, but they may not be the same colours. Remove 4 wires from your strip of 10 (for most kits).


Test with the UltrasonicTest script




build10Step 7: Plug in the servos for the Pan/Tilt assembly

Pan servo is attached to x22/#25 on the PiRoCon board. Tilt servo is attached to x18/#24

Be very careful to ensure correct orientation of the servo connector or the servo will be damaged. The Brown wire is Ground and should be connected to the pins marked G. Orange wire is signal and should be connected to a pin marked S.  Note that Pirocon v2 has the G pins near the centre of the PCB, while v1 has the G pins nearest the edge.

The ultrasonic cable should be plugged into the 4-way male header matching the signals on the sensor: 5V – Trig – Echo – Gnd with 5V nearest centre of PiRoCon board and Gnd nearest the edge. All these are marked on the PCB – just be careful.


Test with the PanTiltTest script or the Tracker script


Step 8. Adding Line Sensors and Obstacle Sensors

This is enough to test most of the system. You can now add line sensors and obstacle sensors if you have them. You can attach these to any of the 6 remaining 3-way positions. Reading the sensor on the selected pin can be done in Scratch GPIO or Python very simply using the Pin or GPIO number labelled next to the connectors chosen.


Obstacle Sensor: These are fitted at the front of the Initio, through the round mountings. Point one slightly left and the other slightly right. They come with ready-made cables so can be attached directly to the PiRoCon. Again, ensure that the Black wire is connected to a pin marked G (for Gnd) and the Yellow wire is connected to a pin marked S (for Signal) on Pirocon.


NOTE: It appears that a batch of these has been shipped with only one mounting collar per sensor. Please contact us if you don’t have 2 per sensor and we will ship the other. While waiting for the missing collars you can fit the sensors loosely in the mounting brackets and still operate them successfully.


Line sensor: These are mounted on the end of the 40mm black pillars so that each sensor is about 1cm above the ground. Use the long Female-Female cables to connect them to the PiRoCon.

We find it is best to use the hole nearest the middle of the sensor for mounting them, but it’s up to you.



For example software we’ve created, we have used the following connections for Line and Obstacle sensors:

  • Left Line sensor: x12/#18
  • Right Line sensor: x13/#27
  • Left obstacle sensor: x07/#04
  • Right obstacle sensor: x11/#07

wiring03 wiring01


PiRoCon Motor Power setting

When using the DC jack from the Initio to power the PiRoCon, you should ensure that the motor power selector jumper is nearest the edge of the board as shown in the bottom right of the photo below:




The Completed Ultimate Kit looks like this:



NB: At this point you will have 3 cables remaining:

  • 2 cables with 4 wires each: Red, Black, Orange, Brown. These are the wheel sensors and it is recommended not to bother with these until you are fully familiar with the system
  • 1 cables with Red & Black wires from the switch board. This is an alternative for the DC jack power cable and is not required for the PiRoCon. Other controller boards have 2-pin screw terminals which you would use this cable with. Ensure that the 2 ends of this cable to not short against each other or anything else


Connecting Wheels Sensors from Initio

The level shifters on the Pirocon are not compatible with the outputs of the wheel sensors, so you must use the wheel sensors at 3.3V and connect the output(s) directly to the GPIO pins. To do this with Pirocon:

  • Remove the blue jumpers from the pin(s) you want to use from the block of 8 jumpers.  Let’s use #22 and #23
  • Connect the Black wire from each wheel sensor to a suitable Gnd pin – you could use the grounds for #22/x15 and #23/x16 as these are not being used otherwise
  • Connect the Red wire from each wheel sensor to a 3.3V connection – there are 2 pins near the pin 25 end of the GPIO connector for this purpose
  • Connect the Orange (or Brown) wire from each wheel sensor to the pins marked #22 and #23 (where the jumpers were removed)
  • You can now read these two pins to get 18 pulses (36 edges) per revolution of each wheel
  • If you additionally use the Brown wires from each sensor (you will need to use 2 more pins and remove 2 more jumpers) you can get additional, out of phase, readings for each wheel. This allows you to determine the direction of travel of each wheel as well as speed. When you detect an edge on one signal, then the level of the other signal will tell you which direction the Initio is going


<< PiRoCon Connection Details