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This version is outdated by a newer approved version.DiffThis version (16 Jan 2018 18:16) was approved by Brandon Bushey.The Previously approved version (12 Dec 2017 21:44) is available.Diff

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Table of Contents

4 – Wire Electrochemical Dual Toxic Gas Demo

The ADuCM360_demo_cn0396 is a dual toxic gas detector demo project, for the EVAL-ADICUP360 base board with additional EVAL-CN0396-ARDZ shield, created using the CrossCore Embedded Studios Interactive Development Environment.(IDE)

General description

The ADuCM360_demo_cn0396 project uses the EVAL-CN0396-ARDZ shield which is a single-supply, low noise, portable gas detector, using a 4-electrode electrochemical sensor, for simultaneous detection of two distinct gases - for this example is used the Alphasense COH-A2 sensor, which detects carbon monoxide(CO) and hydrogen sulfide(H2S).

The EVAL-CN0396-ARDZ board provides a potentiostatic circuit for biasing the electrochemical sensor, along with dual programmable TIA's and 16-bit Sigma-Delta ADC. The TIA's convert the small currents passing in the sensor to a voltage that can be read by the AD7798 a 3-channel, low noise, low power 16-bit ADC that converts the analog voltage into digital data. The 16-bit ADC outputs are received via SPI interface of the EVAL-ADICUP360 board. An ADT7310 digital temperature sensor is also included to measure ambient temperature in order for correction of temperature effects.

The ADuCM360_demo_cn0396 application reads temperature value from ADT7310 and ADC values for each gas channel (CO and H2S), processes the values and make all necessary conversions in order to provide the gas concentrations. A UART interface (115200 baud rate and 8-bits data length) is used to send the results to terminal window. The output data will be displayed continuously considering a data refresh parameter (see DISPLAY_REFRESH).

Based on the maximum sensor sensitivity for each gas the system should be configured before using it. The application will calculate the gas concentration using sensor gas sensitivity and then compensate these values using measured temperature value.

Maximum sensitivity and gas sensitivity are dependent on sensor type. These value will need to be updated in case of using another sensor that the one presented here.

Demo Requirements

The following is a list of items needed in order to replicate this demo.

  • Hardware
    • EVAL-ADICUP360
    • EVAL-CN0396-ARDZ
    • Electrochemical Gas Sensor (included with CN0396)
    • Mirco USB to USB cable
    • PC or Laptop with a USB port
  • Software
    • ADuCM360_demo_cn0396 software
    • CrossCore Embedded Studio (2.7.0 or higher)
    • ADuCM36x DFP (1.0.2 or higher)
    • CMSIS ARM Pack (4.3.0 or higher)
    • Serial Terminal Program
      • Such as Putty or Tera Term

Setting up the hardware

  1. To program the base board, set the jumpers/switches as shown in the next figure. The important jumpers/switches are highlighted in red.
  2. Connect the EVAL-CN0396-ARDZ to the Arduino connectors P2, P5, P6, P7, P8 of the EVAL-ADICUP360 board.
  3. Set the jumpers on EVAL-CN0396-ARDZ board, as shown in the picture below.
  4. Plug in the USB cable from the PC to the EVAL-ADICUP360 base board via the Debug USB.(P14)

Obtaining the source code

We recommend not opening the project directly, but rather import it into CCESand make a local copy in your workspace.

The source code and include files of the ADuCM360_demo_cn0396 can be found on Github:


CrossCore Embedded Studio Application Source Code:

ADuCM360_demo_cn0396 at Github

For more information on importing, debugging, or other tools related questions, please see the tools user guide.

Configuring the Software Parameters

  • Sensor Range - CO_RANGE & H2S_RANGE - maximum value of the gas concentration (ppm) that can be detected by each of the electrodes of the electrochemical gas sensor being used (CN0396.h).
    #define CO_RANGE   1000
    #define H2S_RANGE  200
  • Sensor Gas Sensitivity - CO_SENS & H2S_SENS - sensitivity (nA/ppm) of each of the 2 electrodes of the electrochemical sensor being used (CN0396.h).
    #define CO_SENS    (75 * pow(10, -9)) 
    #define H2S_SENS   (800 * pow(10, -9))
  • Maximum Sensor Gas Sensitivity - MAX_CO_SENS & MAX_H2S_SENS - sensitivity (nA/ppm) of each of the 2 electrodes of the electrochemical sensor being used (CN0396.h).
    #define MAX_CO_SENS  (100 * pow(10, -9)) 
    #define MAX_H2S_SENS (1000 * pow(10, -9))
  • Terminal refresh - DISPLAY_REFRESH parameter - how often to refresh the output data - input time value in [msec] (CN0396.h).
    #define DISPLAY_REFRESH        500

Outputting Data

Serial Terminal Output

  1. In order to view the data, you must flash the program to the EVAL-ADICUP360.
  2. Once complete you will need to switch the USB cable from the DEBUG USB (P14) to the USER USB (P13).
  3. Then follow the UART settings below with the serial terminal program.


Following is the UART configuration. 

  Select COM Port
  Baud rate: 115200
  Data: 8 bit
  Parity: none
  Stop: 1 bit
  Flow Control: none


  • The data output refreshes in the console window at the rate of the “display_refresh” parameter with the following results.

How to use the Tools

The official tool we promote for use with the EVAL-ADICUP360 is CrossCore Embedded Studio. For more information on downloading the tools and a quick start guide on how to use the tool basics, please check out the Tools Overview page.

Importing

For more detailed instructions on importing this application/demo example into the CrossCore Embedded Studios tools, please view our How to import existing projects into your workspace section.

Debugging

For more detailed instructions on importing this application/demo example into the CrossCore Embedded Studios tools, please view our How to configure the debug session section.

Project structure

The ADuCM360_demo_cn0396 is a C project which uses ADuCM36x C/C++ Project structure.

This project contains: system initialization part - disabling watchdog, setting system clock, enabling clock for peripherals; port configuration for SPI1, UART via P0.6/P0.7; SPI, UART read/write functions, AD7798 control, AD5270 and ADT7310 control; gas concentration computation.

In the src and include folders you will find the source and header files related to CN0396 software application. The Communication.c/h files contain SPI and UART specific data, the AD7798.c/h files contain the ADC control, the AD5270.c/h files contain the rheostat control, the ADT73100.c/h files contain the temperature sensor control, and the CN0396.c/h files are for the gas calculations.


The RTE folder contains device and system related files:

  • Device Folder – contains low levels drivers for ADuCM360 microcontroller.(try not to edit these files)
  • system.rteconfig - Allows the user to select the peripherial components they need, along with the startup and ARM cmsis files needed for the project.



End of Document

resources/eval/user-guides/eval-adicup360/reference_designs/demo_cn0396.1516122919.txt.gz · Last modified: 16 Jan 2018 18:15 by Brandon Bushey

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