Getting Started with the ADC Pi

If you’ve ever wanted to connect sensors like temperature or light sensors to your Raspberry Pi, you’ve probably realised that it doesn’t natively support analogue inputs. That’s where the ADC Pi from AB Electronics UK comes in.

The ADC Pi is a high-quality, 17-bit Analogue-to-Digital Converter designed specifically for the Raspberry Pi, offering an easy and reliable way to bring analogue inputs into your projects. In this guide, we’ll walk you through everything you need to know—from setting up the ADC Pi to writing your first Python script.

What is the ADC Pi, and Why Use It?

The ADC Pi is an analogue-to-digital converter board that plugs directly into the 40-pin GPIO header on your Raspberry Pi. It’s ideal for beginners and advanced users alike. Here’s why the ADC Pi is awesome:

• High Resolution: With 17-bit resolution, it’s incredibly precise, perfect for applications where accuracy matters.
• Wide Voltage Range: Each analogue input can measure voltages from 0 to 5V.
• Multiple Channels: It has 8 input channels, so you can connect up to 8 sensors simultaneously.
• Raspberry Pi Compatibility: Designed to work seamlessly with all Raspberry Pi models with a 40-pin GPIO header.
• Built-in Voltage Reference: Ensures stable and reliable readings.

Without an ADC like this, your Raspberry Pi can only process digital signals. With the ADC Pi, you can add analogue sensors to monitor temperature, light, humidity, and much more.

What You’ll Learn

• How to connect the ADC Pi to your Raspberry Pi.
• Installing and using the Python library for the ADC Pi.
• Writing Python code to read data from sensors.
• Tips for testing and troubleshooting your setup.

Step 1: Setting Up the ADC Pi

What You’ll Need:

• A Raspberry Pi with a 40-pin GPIO header (e.g., Raspberry Pi 5, 4, 3, 2, or Zero).
• The ADC Pi board from AB Electronics UK.
• Sensors or analogue devices (e.g., a potentiometer or temperature sensor).
• Jumper wires and a breadboard for testing connections.

Attaching the ADC Pi

The ADC Pi is supplied with the 40 pin GPIO connector and the address select connector unsoldered. Before you can use the ADC Pi on your Raspberry Pi you will need to solder both headers onto the board.

The ADC Pi connects directly to the GPIO header of your Raspberry Pi—no extra wiring needed for the board itself. Simply line up the pins, press it down gently, and it’s ready to go.

If you’re adding sensors, solder cables or use screw terminals on the ADC Pi to connect the signal wires. The inputs are clearly labelled, so you can easily match them to your sensor’s outputs.

Step 2: Installing the Python Library

To communicate with the ADC Pi, you’ll need the Python library provided by AB Electronics UK. Follow these steps to install it:

Open a terminal on your Raspberry Pi.

Update your Raspberry Pi to ensure compatibility:

sudo apt update && sudo apt upgrade

Install the ADC Pi Python library:

Before you can install the library you will need to install the Python3 build and install packages. To install them run the following command.

sudo apt install python3-build python3-installer git

Download the ABElectronics_Python_Libraries to your Raspberry Pi:

git clone https://github.com/abelectronicsuk/ABElectronics_Python_Libraries.git

Navigate into the ABElectronics_Python_Libraries folder and run:

python3 -m build
sudo python3 -m installer dist/*.whl

This library makes it easy to read data from the ADC Pi with simple Python functions.

Step 3: Writing Your First Python Script

Let’s read data from the ADC Pi. Below is a Python script to measure an analogue signal (e.g., from a potentiometer or light sensor):

from ADCPi import ADCPi
import time

# Create an instance of the ADC Pi with the I2C addresses 0x68 and 0x69
adc = ADCPi(0x68, 0x69, 12)  # 12-bit mode for faster readings; use 17 for maximum resolution

while True:
    # Read the voltage on channel 1
    voltage = adc.read_voltage(1)
    print(f"Channel 1 Voltage: {voltage:.2f} V")
    time.sleep(1)

How It Works:

• The ADCPi library handles all the communication with the board.
• The read_voltage(channel) function retrieves the voltage from the specified channel.
• You can change the channel number (1–8) to read from other connected sensors.

Step 4: Connecting Sensors

The ADC Pi supports a wide range of analogue sensors. Let’s say you’re using a light sensor:

1. Connect the sensor’s output pin to one of the ADC Pi’s channels (e.g., Channel 1).
2. Connect the sensor’s power (VCC) and ground (GND) to the corresponding terminals on the ADC Pi.
3. Use the Python script above to read the voltage.

Example Application: For a temperature sensor like the LM35, you can convert the output voltage into a temperature reading using a simple formula:

# Read the voltage from the temperature sensor on Channel 2
voltage = adc.read_voltage(2)
temperature = voltage * 100  # LM35 outputs 10mV per degree Celsius
print(f"Temperature: {temperature:.2f} °C")

Step 5: Testing and Troubleshooting

Testing Your Setup

Before running your scripts, ensure the ADC Pi is properly connected:

• Double-check the GPIO connection.
• Verify the sensor connections (no loose wires).

Run a simple script to confirm everything works. If you’re not getting readings:

• Ensure your sensor is powered.
• Check that the ground wire on your sensor is connected to the ground on the ADC Pi.
• Use a multimeter to check the voltage coming from the sensor.

Common Issues

Incorrect I2C Setup: The ADC Pi uses I2C. Make sure it’s enabled on your Raspberry Pi:

sudo raspi-config

Navigate to Interface Options → I2C and enable it.

Library Errors: If the Python library isn’t installed correctly, re-run the installation steps.

Expanding Your Projects

The ADC Pi is versatile, making it perfect for a variety of projects:

• Environmental Monitoring: Connect temperature, humidity, and light sensors to create a smart weather station.
• DIY Instruments: Use potentiometers to build a custom MIDI controller.
• Home Automation: Monitor sensors like water levels or soil moisture for automated plant care.

Here’s a snippet for logging multiple sensor readings:
for channel in range(1, 9):

voltage = adc.read_voltage(channel)
print(f"Channel {channel}: {voltage:.2f} V")
time.sleep(0.5)

Final Thoughts

The ADC Pi from AB Electronics UK is an incredible tool for bringing analogue inputs to your Raspberry Pi. Whether you’re building a weather station, experimenting with sensors, or creating something entirely unique, the ADC Pi makes it easy and fun.

Now it’s your turn—grab an ADC Pi and start exploring. What will you create next?

FAQs

Q: Does the ADC Pi work with all Raspberry Pi models?
Yes! As long as your Raspberry Pi has a 40-pin GPIO header, the ADC Pi is compatible.

Q: Can I connect more than one ADC Pi?
Absolutely! You can stack up to four ADC Pi boards for 32 input channels.

Q: Can I connect sensors with a voltage greater than 5V?
You can increase the voltage range of the ADC Pi by adding a resistor in series with the input. We have an ADC Pi Resistor Calculator tool that you can use to calculate the correct resistor value for your project.