8 Channel Data Acquisition System

An 8 channel differential input data acquisition system built as a Hat for a Raspberry Pi

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This is a 18 bit 8 channel data acquisition system for Raspberry Pi, based on an AD7609 from Analog devices. This experiment is an attempt to control the device using a parallel interface to achieve it's maximum sample rate of 200k samples/second.

Why the AD7609?

The device was chosen because of its relatively simple interface options, either an SPI interface (Limited to 50 ks/S) or a parallel interface capable of 200ks/S. It has no internal register structure and is a "simple" logical state device. The device has 8 balanced inputs with an input impedance of 1MOhm. If you need unbalanced inputs the AD7608 is an alternative you should look at. It is pin for pin compatible and should function on this PCB without problem. Full details of the AD7609 can be found in the Data sheet.


The KiCad schematic

x-kicad-schematic - 37.47 kB - 07/22/2020 at 10:43



The KiCad PCB file

x-kicad-pcb - 578.08 kB - 07/22/2020 at 10:43



A PDF of the Schematic

Adobe Portable Document Format - 79.74 kB - 07/22/2020 at 10:40



The data sheet from Analog Devices

Adobe Portable Document Format - 1.33 MB - 07/21/2020 at 07:23


  • Project Abandoned for the moment.

    piplay08/06/2022 at 05:31 0 comments

    Sorry to say this project has been abandoned for the moment, We have struck some definite data speed issues that will need a rethink.

    A new modular Isolated acquisition and Thermocouple structure is being designed at the moment and will be up soon.

  • Project Stalled

    piplay11/24/2021 at 23:22 0 comments

    Sorry, this project has stalled for the moment. We will return to it soon.

  • Project Revamp

    piplay08/10/2020 at 09:33 0 comments

    We have created a prototype and written some controlling software., The system works but can not achieve our projected acquisition speed  based on the Raspberry Pi alone. We are investigating using external clocked logic to offload work from the Raspberry Pi but it has delayed the project while we have a rethink.

  • Prototype in Testing

    piplay07/20/2020 at 23:31 0 comments

    We have created the first circuit board and have test software running. At the moment we are refining both the PCB and the software to be more resilient at the low level acquisition tasks and will then move on to a second PCB version and adding functionality to the software.

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