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AD7792 - Microcontroller No-OS Driver

Supported Devices

Evaluation Boards

Overview

The AD7792 is a low power, low noise, complete analog front end for high precision measurement applications. The AD7792 contains a low noise 16-bit Σ-Δ ADC with three differential analog inputs. The on-chip, low noise instrumentation amplifier means that signals of small amplitude can be interfaced directly to the ADC. With a gain setting of 64, the rms noise is 40 nV when the update rate equals 4.17 Hz.

The goal of this project (Microcontroller No-OS) is to be able to provide reference projects for lower end processors, which can't run Linux, or aren't running a specific operating system, to help those customers using microcontrollers with ADI parts. Here you can find a generic driver which can be used as a base for any microcontroller platform and also specific drivers for Renesas platforms.

HW Platform(s):

Driver Description

The driver contains two parts:

  • The driver for the AD7792 part, which may be used, without modifications, with any microcontroller.
  • The Communication Driver, where the specific communication functions for the desired type of processor and communication protocol have to be implemented. This driver implements the communication with the device and hides the actual details of the communication protocol to the ADI driver.

The Communication Driver has a standard interface, so the AD7792 driver can be used exactly as it is provided. There are three functions which are called by the AD7792 driver:

  • SPI_Init() – initializes the communication peripheral.
  • SPI_Write() – writes data to the device.
  • SPI_Read() – reads data from the device.

Driver architecture

The implementation of these three functions depends on the used microcontroller.

The following functions are implemented in this version of AD7792 driver:

Function Description
unsigned char AD7792_Init(void) Initialize AD7792 and check if the device is present.
void AD7792_Reset(void) Sends 32 consecutive 1's on SPI in order to reset the part.
unsigned long AD7792_GetRegisterValue(unsigned char regAddress, unsigned char size) Reads the value of the selected register.
void AD7792_SetRegisterValue(unsigned char regAddress, unsigned long regValue, unsigned char size) Writes a value to the register.
void AD7792_SetMode(unsigned long mode) Sets the operating mode of AD7792.
unsigned char AD7792_Ready(void) Reads /RDY bit of Status register.
void AD7792_SetChannel(unsigned long channel) Selects the channel of AD7792.
void AD7792_SetGain(unsigned long gain) Sets the gain of the In-Amp.
void AD7792_SetReference(unsigned char type) Sets the reference source for the ADC.

Downloads

Renesas RX62N Quick Start Guide

This section contains a description of the steps required to run the AD7792 demonstration project on a Renesas RX62N platform.

Required Hardware

Required Software

Hardware Setup

An EVAL-AD7792EBZ board has to be interfaced with the Renesas Demonstration Kit (RDK) for RX62N:

  EVAL-AD7792EBZ J2 connector Pin DOUT → YRDKRX62N J8 connector Pin 22
  EVAL-AD7792EBZ J2 connector Pin DIN  → YRDKRX62N J8 connector Pin 19
  EVAL-AD7792EBZ J2 connector Pin SCLK → YRDKRX62N J8 connector Pin 20
  EVAL-AD7792EBZ J2 connector Pin CS   → YRDKRX62N J8 connector Pin 15
  EVAL-AD7792EBZ J3 connector Pin AVDD → YRDKRX62N J8 connector Pin 3
  EVAL-AD7792EBZ J3 connector Pin DGND → YRDKRX62N J8 connector Pin 4

Reference Project Overview

The demo program samples channel 1 at 16.7 Hz. The ADC is configured to work in bipolar mode and the gain of the In-Amp is set to 1. The hex values of the configuration and data registers are displayed on the LCD. The value of the Data register is also formatted to be displayed in mV.

Software Project Setup

This section presents the steps for developing a software application that will run on the Renesas Demo Kit for RX62N for controlling and monitoring the operation of the ADI part.

  • Run the High-performance Embedded Workshop integrated development environment.
  • A window will appear asking to create or open project workspace. Choose “Create a new project workspace” option and press OK.
  • From “Project Types” option select “Application”, name the Workspace and the Project “ADIEvalBoard”, select the “RX” CPU family and “Renesas RX Standard” tool chain. Press OK.

  • A few windows will appear asking to configure the project:
    • In the “Select Target CPU” window, select “RX600” CPU series, “RX62N” CPU Type and press Next.
    • In the “Option Setting” windows keep default settings and press Next.
    • In the “Setting the Content of Files to be generated” window select “None” for the “Generate main() Function” option and press Next.
    • In the “Setting the Standard Library” window press “Disable all” and then Next.
    • In the “Setting the Stack Area” window check the “Use User Stack” option and press Next.
    • In the “Setting the Vector” window keep default settings and press Next.
    • In the “Setting the Target System for Debugging” window choose “RX600 Segger J-Link” target and press Next.
    • In the “Setting the Debugger Options” and “Changing the Files Name to be created” windows keep default settings, press Next and Finish.
  • The workspace is created.

  • The RPDL (Renesas Peripheral Driver Library) has to integrated in the project. Unzip the RPDL files (double-click on the file “RPDL_RX62N.exe”). Navigate to where the RPDL files were unpacked and double-click on the “Copy_RPDL_RX62N.bat” to start the copy process. Choose the LQFP package, type the full path where the project was created and after the files were copied, press any key to close the window.
  • The new source files have to be included in the project. Use the key sequence Alt, P, A to open the “Add files to project ‘ADIEvalBoard’” window. Double click on the RPDL folder. From the “Files of type” drop-down list, select “C source file (*.C)”. Select all of the files and press Add.

  • To avoid conflicts with standard project files remove the files “intprg.c” and “vecttbl.c” which are included in the project. Use the key sequence Alt, P, R to open the “Remove Project Files” window. Select the files, click on Remove and press OK.

  • Next the new directory has to be included in the project. Use the key sequence Alt, B, R to open the “RX Standard Toolchain” window. Select the C/C++ tab, select “Show entries for: Include file directories” and press Add. Select “Relative to: Project directory”, type “RPDL” as sub-directory and press OK.

  • The library file path has to be added in the project. Select the Link/Library tab, select “Show entries for: Library files” and press Add. Select “Relative to: Project directory”, type “RPDL\RX62N_library” as file path and press OK.

  • Because the “intprg.c” file was removed the “PIntPrg” specified in option “start” has to be removed. Change “Category” to “Section”. Press “Edit”, select “PIntPRG” and press “Remove”. From this window the address of each section can be also modified. After all the changes are made press OK two times.

  • At this point the files extracted from the zip file located in the “Software Tools” section have to be added into the project. Copy all the files from the archive into the project folder.

  • Now, the files have to be included in the project. Use the key sequence Alt, P, A to open the “Add files to project ‘ADIEvalBoard’” window. Navigate into ADI folder. From the “Files of type” drop-down list, select “Project Files”. Select all the copied files and press Add.

  • Now, the project is ready to be built. Press F7. The message after the Build Process is finished has to be “0 Errors, 0 Warnings”. To run the program on the board, you have to download the firmware into the microprocessor’s memory.
03 Feb 2012 15:32 · dragosb
resources/tools-software/uc-drivers/renesas/ad7792.1330069015.txt.gz · Last modified: 24 Feb 2012 08:36 by dragosb