Wiki

Analog Devices Wiki

English
English
简体中文
简体中文
日本語
日本語
Руccкий
Руccкий
This version (01 Mar 2019 17:12) was approved by Micheál Lambe.

Table of Contents

AD5940_ChronoAmperometric

This example will use EVAL-ADICUP3029 and EVAL_AD5940ELCZ to carry put Chrono-amperometric measurements.

Overview

Chrono-amperometric, or pulse test, is a test in which the voltage across the counter electrode and sense electrode is pulsed, disturbing the normal bias for the electrochemical cell. The current response is measured on the sense electrode through the LPTIA. The measurement technique can have a number of applications. In the case of an electrochemical gas sensor this test checks that the passage of charge between electrodes through the internal electrolyte during oxidation and reduction is operating properly In normal operation, the AD5940 sets the voltage on the counter electrode via VBIAS and the voltage on the sense electrode is set via VZERO. These are typically set to 1.1 V for a zero bias sensor. Then a pulse is applied on VBIAS for a defined duration. The response current is measured using the low power TIA or the high speed TIA, depending on the speed of the response required. In this application the LPTIA is used.

Measurement Requirements

The following is a list of items required to carry out the measurement.

  • Hardware
    • EVAL-ADICUP3029
    • EVAL-AD5940ELCZ
    • Mirco USB to USB cable
    • PC or Laptop with a USB port
    • Custom Cables (Optional)
  • Software
    • AD5940_Amperometric Example Project (Git Lab)
    • Serial Terminal Program, Such as Putty or RealTerm
    • IDE such as IAR or Keil

Setting up the Hardware

  1. Set switch S2 to USB Arduino function in order to view data over UART. The UART baud rate is 230400
  2. Set S5 to Wall/USB to power the board from the USB cable
  3. Place the EVAL-AD5940ELCZ on top of the EVAL-ADICUP3029.
  4. Ensure jumper on JP10 and JP11 is on PIN2 and PIN4
  5. Place jumper in position A on JP6 to connect 6.8K resistor in series with a 10uF capacitor between RE0 and SE0
  6. Plug in the micro USB cable into the (P10) USB port on the EVAL-ADICUP3029, and the other end into the PC or laptop.

Obtaining the Source Code

The source code and include files for the project can be found on Git

AD5940 Source Code

Configuring the Software

To compile and run the example open the project in either Keil or IAR. The AD5940AMPStructInit() function is used to configure application parameters including, pulseAmplitude and pulseLength.

Outputting Data

The measurement results are sent to the PC via UART. To establish connection over UART, connect the Micro-USB cable to the PC and to the EVAL-ADICUP3029 board. A terminal program such as RealTerm or Putty is required to display the results

Following is the UART configuration. 

  Select COM Port
  Baud rate: 230400
  Data: 8 bit
  Parity: none
  Stop: 1 bit
  Flow Control: none

The data on the terminal consists of the Frequency of the excitation signal, the magnitude of the impedance and the phase of the impedance in degrees as in below screenshot.

resources/eval/user-guides/eval-ad5940/software_examples/ad5940_chronoamperometric.txt · Last modified: 01 Mar 2019 15:44 by Micheál Lambe

Page Tools