Connecting the Raspberry Pi and battery pack to the motorboard
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Connecting the Raspberry Pi and battery pack to the motorboard
Your next step is to connect the motorboard to the GPIO pins on the Raspberry Pi, and to the battery pack. This will allow you to power the motorboard and control the motors using the Raspberry Pi.
What you will need
- Raspberry Pi
- Motor controller board (wired up to the DC motors)
- AA battery holder for four AA batteries
- Four AA batteries
- Five jumper leads (female-to-female)
- Screwdriver
You may also need:
- GPIO reference card
Connect the battery pack to the motorboard
The motors require more power than the Raspberry Pi can provide. Therefore, you will use four AA batteries to power them.
The battery pack should include two wires: one red and one black. The red wire is for the positive terminal and needs to be inserted into the VCC terminal block if it is present, or the 'voltage in' terminal block labelled +12V otherwise.
The black wire is the ground wire and must be inserted into the GND terminal to complete the circuit. Make sure all the screws of the terminal blocks are tightened securely.
Insert the four AA batteries into the battery pack and if it has a switch, turn it on. Most motor controllers have a red LED that lights up to show that it is powered on. If the LED is not lit up, the wires may not be connected properly. Also check that your battery pack is full, and the batteries are the right way around.
Receiving input
These instructions are for a L298N dual H-bridge DC stepper motor driver controller board, and they will be similar for most motor controller boards. Other boards may connect differently to the one that I'm using, and some boards can simply be placed onto the Raspberry Pi GPIO pins as a HAT. Check the documentation for your board if you are using a different one.
On this motor controller board there are pins labelled IN1, IN2, IN3, and IN4. Some motorboards also have one or two GND (ground) pins next to the IN pins, but this board does not.
Which GPIO pins you use on your Pi is up to you; I have used GPIO 7, 8, 9, and 10. However, if you use different GPIO pins, make sure you remember which ones, as you will need to refer to them in the code.
Use five female-to-female jumper leads to connect the Raspberry Pi GPIO pins to the pins on the motor controller board. Each DC motor will need to need to use two IN pins to connect to the Raspberry Pi, so that the motor can turn in both directions. You will also need one GND pin to complete the circuits; this can be the same pin for both motors.
| GPIO pin | Connects to | Board pin |
|---|---|---|
| 7 | <–> | IN1 |
| 8 | <–> | IN2 |
| 9 | <–> | IN3 |
| 10 | <–> | IN4 |
| GND | <–> | GND |
If your motorboard does not have a GND pin, use the terminal block that the battery pack also uses. Strip the end of the wire for the GND pin and secure it into the GND terminal block that your battery pack feeds into. There will now be two wires fed into the GND block: one from the battery pack and one from the Raspberry Pi.
Powering the Raspberry Pi
The Raspberry Pi will need its own source of power. For testing, the Raspberry Pi can be plugged directly into the mains power supply. However, when you come to building the body of the buggy and making it move, the Raspberry Pi will need a mobile source of power. A USB powerbank is a good choice, as it will be fairly light for the chassis to carry. Most USB power banks are capable of powering a Raspberry Pi, since they usually have an output voltage of 5 V. Make sure the USB power bank will not shut down the power output after some time, or interrupt the power output when you connect the power bank to mains.
Setting up your Raspberry Pi
If you are not familiar with setting up a Raspberry Pi and using it, follow this guide to Getting started with Raspberry Pi.
The programming language I will be using in this course is Python together with a library called GPIO Zero, which provides an accessible way to control components through the GPIO pins.
Python and GPIO Zero will be installed by default if your Raspberry Pi is running the Raspbian operating system. Follow this guide to Installing GPIO Zero if you are using Raspbian Lite or another operating system.
If you would like to control your Raspberry Pi remotely from another computer, check out our guide to Creating a virtual desktop using VNC Server.
Discussion
Did you have any problems connecting the motorboard to the Raspberry Pi or to the battery pack?
What type of power supply are you using for your Raspberry Pi?
Leave your answers in the comments section below.