ADC Pi

8 Channel 17-bit Single-Ended Analogue to Digital Converter for the Raspberry Pi

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The ADC Pi is an 8-channel, 17-bit analogue-to-digital converter (ADC) expansion board designed for the Raspberry Pi and other compatible single-board computers.

An analogue-to-digital converter (ADC) lets your Raspberry Pi read signals from sensors that measure things like temperature, light, moisture, or voltage. These sensors usually send out analogue signals, smooth, varying voltages, that the Raspberry Pi can’t understand on its own, since it only works with digital binary data (ones and zeros).

An ADC turns those analogue signals into digital values that the Raspberry Pi can process, display, or respond to. This makes an ADC essential if you’re building projects that need to monitor the real world, such as weather stations, plant monitoring systems, or any device that measures physical conditions.

The ADC Pi features two Microchip MCP3424 high-resolution ADC chips, each providing four analogue inputs. These MCP3424 chips are delta-sigma A/D converters with low-noise differential inputs.

Unlike many other Raspberry Pi ADC HATs, the ADC Pi supports stacking, allowing you to connect up to three additional ADC Pi boards or mix with other development boards. This gives you access to up to 32 ADC inputs on a single Raspberry Pi.

Not sure which ADC is right for you?

Have a look at our Analogue to Digital Buyers Guide to compare all of our ADC boards.

We designed the ADC Pi to operate as a single-ended A/D converter, using the internal 2.048V reference voltage with the -V pins tied to ground. A voltage divider on the board scales the input voltage range to a more practical 0–5.06V. In this configuration, each channel provides a 17-bit resolution. If you need to measure higher voltages, you can use our ADC Pi Input Voltage Calculator to determine the required resistor values.

The ADC Pi draws power from the host Raspberry Pi through the GPIO header. Extended GPIO pins allow you to easily stack it with other development boards.

Communication between the two MCP3424 chips and the Raspberry Pi is handled via the I²C protocol. A built-in logic level converter buffers the I²C signals, enabling safe connection of 5V I²C devices to the Pi’s 3.3V I²C bus.

The MCP3424 also includes a programmable gain amplifier (PGA), allowing selectable gains of ×1, ×2, ×4, or ×8 before digital conversion.

You can configure the bit mode resolution and data rate through software via the I²C interface. The available bit modes are:

  • 3.75 samples/sec (17-bit)
  • 15 samples/sec (15-bit)
  • 60 samples/sec (13-bit)
  • 240 samples/sec (11-bit)

Features

  • 8 x 17-bit 0 to 5V Single Ended ADC Inputs
  • Control via the Raspberry Pi I2C port
  • Stack up to 4 ADC Pi boards on a single Raspberry Pi
  • Jumper selectable I2C addresses
  • Buffered 5V I2C port
  • Based on the MCP3424 from Microchip Technologies Inc
  • On-board 2.048V reference voltage (Accuracy  ± 0.05%, Drift: 15 ppm/°C)
  • On-Board Programmable Gain Amplifier (PGA): Gains of 1, 2, 4 or 8
  • Programmable Bit Modes (11, 13, 15 and 17-bit)
  • One-Shot or Continuous Conversion Options

We have a knowledge base article, ADC Sample Rate Comparison, with more detailed sample information and test scripts to compare the different MCP3424 ADC chip bits and sample rates.

Unused inputs should be tied to ground.

Technical Details

Input Ratings & Specifications

Spec
Ratings
Vdd (5V pin on I2C bus)
5.0V
ADC Input Voltage
0V to +5.06V
Maximum ADC Input voltage
VSS–0.4V to VDD+0.4 V
Current at Input Pins
±2 mA
I2C SDA/SCL voltage
5.0 V
I2C port current
100 mA

3D CAD Model

Click to downloadADC Pi  - 3D CAD File (STEP Format)

Board Layout

Schematic

ADC Pi schematic
View the schematic PDF.

Mechanical Drawings

Click the image to enlarge it.

Compatibility

We have tested the ADC Pi on the following platforms.

Model Status
Raspberry Pi Pico series
Raspberry Pi Model A / B
Raspberry Pi 1 Model A+ / B+
Raspberry Pi 2 Model B
Raspberry Pi 3 Model A+ / B / B+
Raspberry Pi 4 Model B
Raspberry Pi 5
Raspberry Pi Zero
Raspberry Pi Zero W / Zero 2 W
Raspberry Pi Compute Module 4 IO Board
Raspberry Pi 400
Orange Pi
Asus Tinker Board
Odroid

Assembly Instructions

The ADC Pi is supplied with the 40-pin GPIO connector, and the 12-pin address connector is unsoldered. We provide the ADC Pi this way because the Raspberry Pi Zero is also supplied without a GPIO header, and the ADC Pi could therefore be fitted both above or below the Raspberry Pi Zero.

Before using the ADC Pi, you must solder both connectors onto the PCB. We suggest soldering the 40-pin GPIO connector first and then the address-select connector. Soldering the address select connector first will make it difficult to access the three corner pins on the GPIO connector.

The ADC Pi Plus assembly video shows the steps needed to assemble the ADC Pi.

Assembly Guide Video

Watch our assembly guide on YouTube. (opens in a new window)

PCB Header Assembly Jig

Download and print our PCB Header Assembly Jig to hold your circuit board when soldering the header pins.

Use

I2C Address Selection

The MCP3424 analogue to digital converter contains two address select pins which can be tied to Vss, Vdd or left floating. This gives 8 possible I2C addresses for each chip. The ADC Pi contains two MCP3424 chips so that you can stack up to 4 ADC Pi boards on a single Raspberry Pi. To simplify address selection, we have included a set of address selection pins which can be configured using the included jumpers. The illustrations below show the four recommended configurations for your ADC Pi and the associated I2C addresses.

Note:
Disconnect the ADC Pi from the Raspberry Pi before changing the address pins. You may need to short the 5V and ground with a resistor to discharge the capacitors for the new addresses to be recognised.

Address selection pins

Warning

Do not under any circumstances connect the two centre pins. This will create a direct short between the 5V and ground pins and damage or destroy your Raspberry Pi and ADC Pi board.

Warning about address selection

I2C Address Table

Adr 0 Adr 1 I2C Address
Low or Float Low or Float 0x68
Low Float 0x69
Low High 0x6A
Float Low 0x6B
High Low 0x6C
High Float 0x6D
High High 0x6E
Float High 0x6F

Recommended Address Configurations

Configuration 1:

Analogue Channels 1-4 = I2C Address: 0x68
Analogue Channels 5-8 = I2C Address: 0x69

Address Configuration 1

Configuration 2:

Analogue Channels 1-4 = I2C Address: 0x6A
Analogue Channels 5-8 = I2C Address: 0x6B

Address Configuration 2

Configuration 3:

Analogue Channels 1-4 = I2C Address: 0x6C
Analogue Channels 5-8 = I2C Address: 0x6D

Address Configuration 3

Configuration 4:

Analogue Channels 1-4 = I2C Address: 0x6E
Analogue Channels 5-8 = I2C Address: 0x6F

Address Configuration 4

Datasheets

MCP3424

 

Code Libraries and Tutorials

This development board has Python, MicroPython, C, C++, Node.JS, .Net Core, Arduino and Home Assistant libraries available to get you started with your next project.  All of our software libraries are open source and can be download from our GitHub repository or by clicking on the logos below for your selected programming language.

ADC Pi Articles & Tutorials

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Important Information

This development board/kit is intended for use for ENGINEERING DEVELOPMENT, DEMONSTRATION, OR EVALUATION PURPOSES ONLY and is not considered by abelectronics.co.uk to be a finished end-product fit for general consumer use. As such, the goods being provided are not intended to be complete in terms of required design-, marketing-, and/or manufacturing-related protective considerations, including product safety and environmental measures typically found in end products that incorporate such semiconductor components or circuit boards. Persons handling the product(s) must have electronics training and observe good engineering practice standards. This development board/kit does not fall within the scope of the European Union directives regarding electromagnetic compatibility, restricted substances (RoHS), recycling (WEEE), FCC, CE or UL, and therefore may not meet the technical requirements of these directives or other related directives. Note: documents in Portable Document Format (PDF) require Adobe Acrobat Reader 5.0 or higher to view, download Adobe Acrobat Reader or other PDF reading software for your computer or mobile device.

Shipping and Delivery

For orders under £35 and tracked orders, the following delivery charges apply.

Shipping Rates

United Kingdom

Service Cost  Estimated Delivery Time 
Royal Mail 1st Class £2.49 1 - 3 days (Mon - Sat)
Royal Mail Special Delivery (Tracked) £8.49 Next day (Mon - Sat)

European Union

Deliveries to: Austria, Belgium, Bulgaria, Croatia, Republic of Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Poland, Portugal, Romania, Slovakia, Slovenia, Spain and Sweden. 

Service Cost  Estimated Delivery Time 
Royal Mail Airmail Service £4.29 3-5 Working Days **
Royal Mail International Tracked and Signed £12.99 3-5 Working Days **

Rest of the World

Service Cost  Estimated Delivery Time 
Royal Mail Airmail Service £5.99 5-7 Working Days **
Royal Mail International Tracked and Signed £18.99 5-7 Working Days **

* Free delivery uses the Royal Mail 1st Class service for UK orders and Royal Mail Airmail Service for international orders.

** All International destinations are subject to customs clearance at the destination country, which can add a short delay to your delivery times. Additional import duty may be charged for your order by customs on arrival to your country based on the order value.

We have a full list of all available delivery destinations on the Shipping Country List.

We aim to dispatch your order within 1 working day.  

Working days are normal weekdays; dispatch times do not include Saturdays, Sundays and national holidays. Delivery transit times do not include national holidays and Sundays but may include Saturdays, depending on the delivery service provider in the destination country.

You can view details of international shipping issues and delays with the Royal Mail airmail service at Royal Mail International Incident Bulletin.

You can check the status of your order by going to the My Account area of the website.

Import One-Stop Shop (IOSS) FAQ

What is the Import One-Stop Shop (IOSS)?

The Import One-Stop Shop (IOSS) is a system introduced by the European Union to simplify VAT collection for goods valued at €150 or less that are shipped to customers in the EU from outside the EU. By using IOSS, sellers collect VAT at the point of sale, ensuring that buyers do not have to pay additional import taxes or customs fees upon delivery.

How does IOSS benefit me as a customer?

IOSS makes your shopping experience easier and more transparent by:

Including VAT in the purchase price you see at checkout.

Eliminating unexpected customs charges or fees upon delivery.

Reducing potential delivery delays caused by customs clearance.

Will I have to pay any additional charges when my order is delivered?

No. If your order is covered by IOSS, all applicable VAT and import charges are already included in the price you pay at checkout. There will be no additional charges when your order is delivered.

How do I know if my order is covered by IOSS?

All orders shipped to EU countries and valued at €150 or less are covered by our IOSS registration. If your order qualifies, the VAT and import fees will be automatically calculated and included in the total price during checkout.

Does IOSS apply to all products?

IOSS applies to goods valued at €150 or less that are shipped from outside the EU to customers in EU member states. Certain items, such as excisable goods (e.g., alcohol or tobacco), may not qualify for IOSS coverage.

What happens if my order exceeds €150?

For orders valued above €150, IOSS does not apply. In such cases, import VAT and any applicable customs duties will need to be paid separately, usually upon delivery. We recommend checking your local regulations for further details.

Do I need to do anything to use IOSS?

No action is required on your part. We handle all the necessary IOSS processes on our end to ensure your order is VAT-compliant and free from additional import fees.

Does IOSS reduce delivery times?

Yes, IOSS can help speed up delivery times by streamlining the customs clearance process. Since VAT is prepaid, your order is less likely to be delayed during customs inspections.

Is IOSS available in all EU countries?

Yes, IOSS applies to all EU member states. Regardless of where you are in the EU, you can enjoy the benefits of IOSS when shopping with us.

Can I claim VAT back if I am VAT registered in the EU?

If you are VAT registered in the EU and wish to claim VAT back, please use the Guest Checkout and enter your VAT registration details before placing your order. It is not possible to enter your VAT details when using the PayPal express checkout.

What should I do if I still have questions?

If you have any further questions about IOSS or your order, feel free to contact our customer support team. We’re here to help!

Delivery Duty Unpaid for orders sent outside of the United Kingdom and EU over 150 euros

All orders sent to countries other than the United Kingdom and EU over 150 euros are shipped on a DDU (Delivery Duty Unpaid) basis, and the recipient may be subject to local taxes and customs import duty, which is charged on the value of the order.

Payment of these fees is the sole responsibility of the customer. 

Order Tracking

Our standard shipping service is not tracked, and we cannot supply tracking information for your order.

We can offer alternative shipping using Royal Mail, tracked and signed for service. You can select this option at checkout. Please note full end-to-end tracking depends on the tracking service from the regional postal service in the destination country.

Once your order has been sent, you can view your tracking code, which is available in the My Account section. Please allow up to 72 hours for your tracking code to be added to your order after despatch.

Returns

Our 180-day returns guarantee means that if for any reason you are unhappy with your purchase, you may return it to us in its original condition within 180 days of the date you received the item, unopened (with any seals and shrink-wrap intact), and we will issue a full refund for the price you paid for the item. We can only accept the return of opened items if they are faulty.

All Raspberry Pi add-on boards are checked on a Raspberry Pi during production, and all inputs are checked to ensure the inputs and outputs are within the specified ratings.

We cannot accept returns for faults caused by over-voltage being applied to inputs on the boards by the purchaser.

When returning an item to us, please clearly state why you are returning your parcel and whether you require a refund or exchange. Please note that the parcel is your responsibility until it reaches us, so we recommend you send it via registered or recorded post. 

The time it takes for a refund to reach the customer depends on the banks involved. It would normally take 3 - 5 working days to complete it.

Sales Tax

United Kingdom VAT at 20% is added to all orders for UK destinations. VAT is not added to NON-UK and EU destinations where the order total is more than 150 euros.

We are not responsible for any import taxes or VAT on the orders in the destination country. Import duty/tax is always paid by the person/company receiving the parcel/order.

Removed Delivery Destinations

We regret that we had to remove the following countries from our delivery destinations due to a very high failure rate of our parcels being delivered using the Royal Mail airmail service. This resulted in us refunding all of the missing orders, and we cannot continue to make such large losses by sending parcels to destinations where a large percentage of the items are lost in the postal systems.

Brazil, China, Israel, Mexico, Saudi Arabia, Singapore, Sri Lanka, Taiwan, Turkey, USA (due to shipping tariffs)  and the United Arab Emirates.

Also, due to problems with the courier delivering parcels to these destinations, we cannot use a third-party courier service for these delivery destinations due to the extra costs involved.

Customers can purchase our products from one of our international resellers

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