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This version (09 Oct 2012 10:51) was approved by DragosB.The Previously approved version (01 Jun 2012 12:32) is available.Diff

AD7799 - Microcontroller No-OS Driver

Supported Devices

Evaluation Boards

Overview

The AD7798/AD7799 are low power, low noise, complete analog front ends for high precision measurement applications. The AD7798/AD7799 contains a low noise, 16-/24-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 27 nV for the AD7799 and 40 nV for the AD7798 when the update rate equals 4.17 Hz.

On-chip features include a low-side power switch, reference detect, programmable digital output pins, burnout currents, and an internal clock oscillator. The output data rate from the part is software-programmable and can be varied from 4.17 Hz to 470 Hz.

The part operates with a power supply from 2.7 V to 5.25 V. The AD7798 consumes a current of 300 μA typical, whereas the AD7799 consumes 380 μA typical. Both devices are housed in a 16-lead TSSOP package.

Applications
  • Weigh scales
  • Pressure measurement
  • Strain gauge transducers
  • Gas analysis
  • Industrial process control
  • Instrumentation
  • Portable instrumentation
  • Blood analysis
  • Smart transmitters
  • Liquid/gas chromotography 6-digit DVM

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 AD7799 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 AD7799 driver can be used exactly as it is provided. There are three functions which are called by the AD7799 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 AD7799 driver:

Function Description
unsigned char AD7799_Init(void) Initializes AD7799 and checks if the device is present.
void AD7799_Reset(void) Sends 32 consecutive 1's on SPI in order to reset the part.
unsigned long AD7799_GetRegisterValue(unsigned char regAddress, unsigned char size) Reads the value of the selected register.
void AD7799_SetRegisterValue(unsigned char regAddress, unsigned long regValue, unsigned char size) Writes a value to the register.
void AD7799_WaitRdyGoLow(void) Waits for RDY pin to go low.
void AD7799_SetMode(unsigned long mode) Sets the operating mode of AD7799.
void AD7799_SetChannel(unsigned long channel) Selects the channel of AD7799.
void AD7799_SetGain(unsigned long gain) Sets the gain of the In-Amp.
void AD7799_SetReference(unsigned char type) Enables or disables the reference detect function.

Downloads

Renesas RL78G13 Quick Start Guide

This section contains a description of the steps required to run the AD7799 demonstration project on a Renesas RL78G13 platform.

Required Hardware

Required Software

Hardware Setup

An EVAL-AD7799EBZ has to be interfaced with the Renesas Demonstration Kit (RDK) for RL78G13:

  EVAL-AD7799EBZ Pin CS   → YRDKRL78G13 J11 connector Pin 1
  EVAL-AD7799EBZ Pin DIN  → YRDKRL78G13 J11 connector Pin 2
  EVAL-AD7799EBZ Pin DOUT → YRDKRL78G13 J11 connector Pin 3
  EVAL-AD7799EBZ Pin SCLK → YRDKRL78G13 J11 connector Pin 4
  EVAL-AD7799EBZ J3 connector Pin AVDD → YRDKRL78G13 J11 connector Pin 6
  EVAL-AD7799EBZ J3 connector Pin DGND → YRDKRL78G13 J11 connector Pin 5

Software Setup

With the Applilet3 for RL78G13 tool the following peripherals have to be configured:

CSI10 (Clocked Serial Interface 10) – For the AD7792 part and the ST7579 LCD

Choose to generate the Transmit/receive function for the CSI10 and configure the interface with the following settings:

  • Transfer mode setting: Single transfer mode
  • Data length setting : 8 bits
  • Transfer direction setting: MSB
  • Specification of data timing: Type 1
  • Transfer rate setting – Clock mode: Internal clock (master)
  • Transfer rate setting – Baudrate: 1000000 (bps)
  • Interrupt setting – Transfer interrupt priority (INTCSI10): Low
  • Uncheck the callback functions.

TM00 (Timer 00) – For the DelayMs() function

Configure TM00 as an interval timer:

  • Interval timer setting - Interval value(16 bits): 1 ms
  • Interval timer setting - Uncheck Generates INTM00 when counting is started
  • Interrupt setting - Uncheck End of timer channel 0 count, generate an interrupt (INTM00)

Watchdog Timer

Disable the watchdog timer:

  • Choose for the Watchdog timer operation setting: Unused option.

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 Tutorial

This section presents the steps for developing a software application that will run on the Renesas Demo Kit for RL78G13 for controlling and monitoring the operation of the ADI part.

Two software applications have to be used: Applilet3 for RL78G13 (a tool that automatically generates device drivers for MCU peripheral functions) and IAR Embedded Workbench for Renesas RL78 (the integrated development environment).

Step 1 - Applilet3 for RL78G13

  • Run the Applilet3 for RL78G13 tool and create a new project for R5F100LE processor. Select IAR Compiler build tool, a project name, a location for the new project and press OK.

  • Keep the default Pin assignment setting and click Fix settings.

  • Now the desired peripherals can be configured and the code can be generated. For example, if the clocked serial interface 10 (CSI10) has to be configured, select the Serial peripheral, choose for the Channel 2 of Serial Array Unit 0 (SAU0) the CSI10 interface, Transmit/receive function option and then go to CSI10 tab.

  • To configure the CSI10 interface for serial transmissions of 8 bits, with MSB first, with the data captured on clock's rising edge, with a frequency of the clock of 1 MHz and the idle state high, the settings from the following image have to be made.

  • After all the desired peripherals are configured click on the Generate Code button and a new workspace and a new project for the IAR Embedded Workbench will be generated. After the code was generated close the Applilet3 for RL78G13 tool.

Step 2 - IAR Embedded Workbench for Renesas RL78

  • Run the IAR Embedded Workbench and open the workspace created with the Applilet3 tool.

  • Copy the files extracted from the zip file into the user_src folder, located in the project’s folder.

  • The new source files have to be included into the project. Add in the user_src group the files from the corresponding folder (Right click on the group and select Add – Add Files…). Because a new Main file was included the r_main.c file from the applilet_src group has to be deleted (Right click on the file and select Remove).

  • Now the debugger driver has to be selected from the project’s options. Right click on the project name and select Options. From the Debugger category choose the TK Debugger Driver.

  • Now, the project is ready to be compiled and downloaded on the board. Press the F7 key to compile it. Press CTRL + D to download and debug the project.

29 Feb 2012 17:01 · Dragos Bogdan

Renesas RX62N Quick Start Guide

This section contains a description of the steps required to run the AD7799 demonstration project on a Renesas RX62N platform.

Required Hardware

Required Software

Hardware Setup

An EVAL-AD7799EBZ board has to be interfaced with the Renesas Demonstration Kit (RDK) for RX62N:

  EVAL-AD7799EBZ Pin DOUT              → YRDKRX62N J8 connector Pin 22
  EVAL-AD7799EBZ Pin DIN               → YRDKRX62N J8 connector Pin 19
  EVAL-AD7799EBZ Pin SCLK              → YRDKRX62N J8 connector Pin 20
  EVAL-AD7799EBZ Pin CS                → YRDKRX62N J8 connector Pin 15
  EVAL-AD7799EBZ J3 connector Pin AVDD → YRDKRX62N J8 connector Pin 3
  EVAL-AD7799EBZ 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 · Dragos Bogdan

More information

01 Jun 2012 12:21