AD7799-微控制器无操作系统驱动程序

消耗积分:3 | 格式:pdf | 大小:1.51MB | 2021-04-24

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This version (25 Jan 2021 05:42) was approved by Robin Getz.The Previously approved version (25 Jan 2021 05:24) is available.

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