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This version is outdated by a newer approved version.This version (31 Oct 2016 12:14) is a draft.Approvals: 0/1
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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 GNU ARM Eclipse Plug-ins in Eclipse environment.
General description
This project is a good example for how to use EVAL-ADICUP360 board in different combinations with shields boards.
The ADuCM360_demo_cn0396 project uses the EVAL-CN0396-ARDZ shield which is a 4–Wire Electrochemical Dual Toxic Gas Sensing System.
(BOARD PICTURE WITH ADICUP360)
The EVAL-CN0396-ARDZ shield circuit 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 ADC. The 16-bit ADC value is received via SPI interface of the EVAL-ADICUP360 board, where the gas concentrations are computed. A digital temperature sensor is also included to measure ambient temperature in order for correction of temperature effects.
The ADuCM360_demo_cn0396 application configures the necessary components, processes ADC output value and make all necessary conversions in order to provide the gas concentration. A UART interface (9600 baud rate and 8-bits data length) is used to send the results to terminal window: ADC Data Register codes, ADC Input Voltage volts, Gas Concentration Parts Per Million(PPM), and Ambient Temperature degrees Celsius are the outputs provided in the terminal window.
At the start of the project, the software computes the necessary parameters and configure the digital rheostats(AD5270) of both TIA's. The required parameters are the sensor sensitivity and sensor range. There are 2 sets of these parameter for the 2 target gases. These can be modified by changing the values of the constants CO_SENS/H2S_SENS and CO_RANGE/H2S_RANGE found in the CN0396.h header file of the project. See the “Project Structure” section for more details.
Once configuration is complete, the software remains in a loop and continuously reads data from the ADC. Data can be read from a terminal by pressing the <Enter> key on the computer's keyboard.
Setting up the hardware
Connect the EVAL-CN0396-ARDZ to the Arduino connectors P4, P5, P6, P7, P8 of the EVAL-ADICUP360 board.
Extremely important to plug in an acceptable power supply to the barrel jack P11 to supply power for the EVAL-CN0396-ARDZ. The boards will not work if you try only to power it from the DEBUG_USB or the USER_USB.
In order to program the base board you need to use the DEBUG USB, and you will need to use the USER USB to communicate with the serial terminal program. The important jumpers and switches configurations are highlighted in red.
The ADuCM360_demo_cn0396 uses UART connection via P0.6/P0.7 and SPI1 channel of the ADuCM360 to communicate with EVAL-CN0396-ARDZ board.
Obtaining the source code
We recommend not opening the project directly, but rather import it into Eclipse and make a local copy in your Eclipse workspace.
The source code and include files of the ADuCM360_demo_cn0396 can be found on Github:
Importing the ADuCM360_demo_cn0396 project
The necessary instructions on how to import the ADuCM360_demo_cn0396 project form the projects examples in the Git repository, can be found in How to import existing projects from the GIT Repository page.
Debugging the ADuCM360_demo_cn0396 project
- A debug configuration must be set up for this project in order to have the possibility to program and to debug the ADuCM360_demo_cn0396 project. To do this, follow the instructions from Setting up a Debug Configuration Page.
- Make sure the target board is connected to the computer (via DEBUG USB) and using the tool bar, navigate to the small Debug icon
and select the debugging session you created. The application will programmed and the program execution will stop at the beginning of the main() function.
- Use step-by-step execution or directly run the program.
After completion of the steps above the program will remain written into the system flash and it will run by default every time the board is powered up.
Project structure
The ADuCM360_demo_cn0396 project use 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 control and 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 contin the temp sensor control, and the CN0357.c/h files contain configurations and computations specific to the gas detector application.
In the appropriate header files you can configure next parameters:
- Sensor Range - CO_RANGE & H2S_RANGE - maximum value of the gas conentration (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 100
- Sensor 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 (700 * pow(10, -9))
The system folder contains system related files (try not to change these files):
- ADuCM360 – contains low levels drivers for ADuCM360 microcontroller.
- CMSIS – contains files related to ADuCM360 platform, such as: ADuCM360.h (registers definitions), system_ADuCM360.c/h (system clock), vectors_ADuCM360.c (interrupt vector table).
- cortexm – contains files for system management (start-up, reset, exception handler).
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resources/eval/user-guides/eval-adicup360/reference_designs/demo_cn0396.1477912472.txt.gz · Last modified: 31 Oct 2016 12:14 by Veronica Lupei