pipyadc 2.1

Python package for interfacing Texas Instruments ADS1255 and ADS1256 SPI bus based ADCs with the Raspberry Pi

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