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.