DIY DAQ: Make an Arduino Data Acquisition System

By Rolland Maro

 

This project was made as part of my senior project at my university. The idea behind the device was to make a data logger that can be carried around a lab without the need to connect to a computer. In this segment, we will cover the components used for this project. Later, we’ll get into calibrating the sensors, setting up software programs, and running some experiments.

 

 

System Overview

 

What Does it Measure?

The following table shows the parameters to be measured and the sensors used to measure them.

 

S/N Measurement variable Sensor Range
1 Temperature Thermocouple(K-type) -250°C-1250°C
2 Mass Electronic load cell 0 – 1 Kg
3 Flow rate Hall Effect Flow meter 1 – 30 Litres/min

 

DAQ System Components

Data Transmission and Storage

CD4021BE Shift register

 

This device is used to convert a parallel input to a serial output, and thus, it enables the use of fewer input pins in the microcontroller. It’s an 8-bit static shift register and therefore converts 8 parallel inputs to the serial transfer.

 

Arduino UNO

 

The microcontroller is used to link all the components, get the digital data from all the ADCs, process them, and store them on the memory card. It also distributes power to all of the sensors.

 

Arduino Micro SD Card Module

The communication between the microcontroller and the SD card uses SPI. The functions of the module are: Formatting and preparing the memory card, file naming, as well as opening and closing files.

 

Signal Conditioning

MAX6675 Thermocouple

The MAX6675 performs cold-junction compensation and digitizes the signal from a type-K thermocouple. The data is output in a 12-bit resolution. It resolves temperatures to 0.25°C, allows readings as high as +1024°C. The chip can also detect an open thermocouple.

 

HX711 Load Cell

By connecting the amplifier to the microcontroller, the changes in the resistance of the load cell can be read and with some calibration, very accurate weight measurements are obtained.

 

Sensors

Temperature Thermocouple

It is a K type thermocouple with a Chromel {90% nickel and 10% chromium} Alumel {95% nickel, 2% manganese, 2% aluminium and 1% silicon} junction. It is has a temperature range of 0 to 800°C. It resistive to oxidation at higher temperatures but vulnerable to sulfur attacks.

 

Weighing Load cell

The load cell used has two strain gauges. Strain (a planar resistor) deforms/stretches/contracts when the material of the load cells deforms appropriately. The limit for the strain gauge used is 5 Kg. Exceeding this limit will cause the load cell to deform permanently.

 

Flow sensor/Hall Effect Flow Meter

The Hall-effect flow sensor outputs approximately 4.5 pulses per second per liter/minute of flow. The pulses increase with an increase in the flow rate and the maximum flow rate is 30 L/min.

 

Integrating the Components

The integration of the system is done using the parts shown above. Integration is done first using simulation by Proteus Isis design suite for configuring and arranging the electronic components and developing a program that will be used for the device. The block diagram and schematic below show the general method used in the integration of the DAQ system.

 

 

Schematic is based on a design from The Engineering Projects

 

Next time, we will set the system up and run some experiments!

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Showing 4 comments
  • Thomas
    Reply

    This is an amazing project and I am highly interested in it, would you be willing to talk me me about it in more detail, or letting me know when you will write the continuing parts? Thank you!

    • Tim Youngblood
      Reply

      Hi Thomas. I’m glad you liked it! We will be publishing the rest of the project next week. I let the author know that you’d like to discuss the project with him. He should contact you via email soon :)

    • Tim Youngblood
      Reply

      Hi Thomas, we just published the second part!

      https://diyhacking.com/diy-daq-arduino-calibrating-sensors/

      There is a PDF of Rolland’s original project report at the bottom of that article as well if you’re looking for additional information :)

      • Thomas
        Reply

        Thank you for letting me know!

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