PiPyADC

Python module for interfacing Texas Instruments ADS1255 and ADS1256 SPI bus based analog-to-digital converters with the Raspberry Pi.

This is a Python-based implementation using the pigpio Python interface to access the Raspberry Pi hardware through the pigpio system service.

On a Raspberry Pi 3, multi-channel ADC reads require a time overhead in the order of one millisecond per sample which makes this library suitable for low-speed, high resolution data acquisition.

As the ADS125x devices feature a sophisticated, configurable, hardware-based down-sampling filter, there is no penalty in terms of accuracy.

NEW in version 2:

• Uses the pigpio API instead of the deprecated wiringpi library
• Using pgpio, the user scripts do not have to be run as root any more
• Working implementation for multiple ADS125x devices on the same SPI bus
• Proper configuration of unused chip-select line for the Waveshare example

Since version 2.1:

• ADS1256 now supports the Python with statement by acting as a Context Manager, allowing for automatic clean-up of SPI device and pigpio resources at exit. (See waveshare_example.py)
• Many bug-fixes involving initialisation and clean-up and running multiple devices on the same SPI bus

Limitation:

• Same as for version 1: This does not feature high-speed or low delays

Download: https://github.com/ul-gh/PiPyADC

Documentation of pigpio library: https://abyz.me.uk/rpi/pigpio/python.html
Uses code from: https://github.com/heathsd/PyADS1256

License: GNU LGPLv2.1, see: https://www.gnu.org/licenses/old-licenses/lgpl-2.1-standalone.html

Ulrich Lukas, 2022-08-30

Run example on Raspberry Pi OS:

Install:

# numpy is optional for running the Isoflux hardware examples
sudo apt install python3-pip python3-numpy pigpio python3-pigpio git
pip3 install pipyadc

Enable pigpio system service (started at boot)

sudo systemctl enable pigpiod.service

Activate SPI bus and reboot system

# Using raspi-config or, alternatively, using following command:
sudo sed -E -i s/"(#)(dtparam=spi).*"/"\2=on"/ /boot/config.txt
sudo reboot

Run example:

git clone https://github.com/ul-gh/PiPyADC
cd PiPyADC/examples/waveshare_board
./waveshare_example.py