Pi-SPi-8AI Raspberry Pi Analog Input (4 - 20 mA) Interface

Pi-SPi-8AI Raspberry Pi Analog Input (4 - 20 mA) Interface

Regular price $25.95 USD Sale

The PI-SPI-8AI+ module is replacing the popular PI-SPI-8AI. All features remain the same with a few enhancements:

The Pi-SPi-8AI+ is based on the popular VP-EC-8AI 8 channel 4-20 mA input module, and the Microchip MCP3208 12 bit A/D converter.

The 26 pin GPIO port is duplicated on either side of the module, so more modules can be "daisy chained" together.

With the latest libwidgetlords v2.1 release, up to 4 PI-SPI-8AI+ modules can be connected together giving a total of 32 analog inputs to one Raspberry Pi.

Application Note: Raspberry Pi with 32 Analog Inputs

All Accessories Including Ribbon Cables Sold Separately

 Node-Red support is available.

These are the standard versions of analog inputs available:

Inputs 1 thru 8 are 4-20 mA (Load Resistor 150 Ohms)

Inputs 1 thru 4 are 4-20 mA Input (load Resistor 150 Ohms)
Inputs 5 thru 8 are 0 to 6.6 VDC Input

Inputs 1 thru 8 are 10K Thermistor Inputs
for Temperature Sensor Applications

Inputs 1 thru 4 are 4-20 mA Input (load Resistor 150 Ohms)
Inputs 5 thru 8 are 10K Thermistor Inputs
for Temperature Sensor Applications

Inputs 1 thru 4 are 10K Thermistor Inputs
Inputs 5 thru 8 are 0 to 6.6 VDC Inputs
for Temperature Sensor and Voltage Input Applications

Each channel can be configured as either mA or Voltage. Another feature is all inputs can easily be configured for thermistor input making the Pi-SPi-8AI an 8 channel temperature sensor module.

Changing an Input Type  is as easy as removing and adding a solder jumper on the back of the module - here is the A1 jumper selection:


mA = 0 to 20 mA
TH = 10K Thermistor Input for temperature applications
5 VDC = 0 to 6.6 VDC Input
10 VDC  = 0 to 12 VDC Input

GPIO Port Pins


Power Input:  5VDC via 26 Pin Ribbon Cable (Powered from the Raspberry Pi 5VDC)
Local Power:  3.3 via LDO Regulator for logic
Field Power:  Barrel Jack and/or Terminal Block (Not required for module operation) (Provided as a convenience for field transmitters)
Interface:  SPI Communications: MOSI, MISO, CLOCK and 4 Chip Select
Input Channels:  8 Channels
A/D:  Microchip MCP3208
Resolution:  12 bit, Single Ended
Sample Speed:  Up to 100KHz on the SPI bus
Analog Inputs:   mA Option:  150 Ohm Load resistor
        Thermistor Option:  10K NTC (10K Load)
        5 VDC Option:   0 to 6.6 VDC
        10 VDC Option:   0 to 11 VDC
Calibration:  Raw A/D values, cal factors stored in user application code
Connections:  Dual 26 Pin Ribbon Cable Headers, Front and rear 8 point terminal blocks,  Barrel Jack for Field power (2.2 x 5 mm)
Dimensions:   3.345” L x 2.2” W x .55” H
Weight:   40 grams (Typical)
Software:  Compatible with Raspberry Pi series 4 and 5 when using the libwidgetlords libraries, (Python, C and Node-Red Support)
Indicators:  Blue LED for Local Power,  Blue LED for Field Power

Download a PDF copy of the PI-SPI-8AI+ Catalog Sheet


Pi-SPi-8AI Accessories (Sold Separately) :

  • Pi-SPi-PS-24VDC Field Power Supply
  • Pi-SPi-CABLE-40x26-2 (40 Pin to 26 Pin x 2") Required to connect to RPi
  • Pi-SPi-CABLE-40x40-2 (40 Pin to 40 Pin x 2")
  • Pi-SPi-CABLE-26x26-2 (26 Pin to 26 Pin x 2") Required to connect to PI-SPI Module
  • Pi-SPi-MTG-HDW Mounting hardware 4x1/2" Aluminum spaces c/w 8 x 4-40 Stainless Steel Screws

For 4-20mA transmitter descriptions and connections, please visit:

4-20 mA Current Loop

Sample Software (Python)

Please download the latest Widgetlords libwidgetlords library. The instructions can be found at

Getting Started with PI-SPI Libraries

All of the sample code examples are based on the latest library installation. Please note the code samples all use Python 3.

Basic Python "Read" A/D Counts Program:

from time import sleep
from widgetlords.pi_spi import *

inputs = Mod8AI()

while True:


The PI-SPI-8AI sample code programs and instructions can be found at

PI-SPI-8AI Python Code Samples

A complete set of Python demo code examples for the PI-SPI and PI-SPI-DIN series can be found on our GitHub repository:


For DIN Rail applications, the PI-SPI-ENC series of DIN mount rail enclosures are available in the Accessories Collection

For high density applications, the WL-MIO series can pack 32 I/O points in just 8.25" of DIN rail.

The WL-MIO Collection.

The WL-MIO Series Product Description.