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AD799x-適用于微芯片微控制器平臺的無操作系統驅動程序

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資料介紹

This version (22 Jul 2019 13:13) was approved by Andrei Drimbarean.The Previously approved version (10 Jul 2013 15:04) is available.

AD799x - No-OS Driver for Microchip Microcontroller Platforms

Evaluation Boards

PmodAD2
EVAL-AD7991EBZ
EVAL-AD7995EBZ

Overview

The AD7991/AD7995/AD7999 are 12-/10-/8-bit, low power, successive approximation ADCs with an I2C?-compatible interface. Each part operates from a single 2.7 V to 5.5 V power supply and features a 1 μs conversion time.

Each AD7991/AD7995/AD7999 provides a 2-wire serial interface compatible with I2C interfaces. The AD7991 and AD7995 come in two versions and each version has an individual I2C address (see Table 8 of data sheet for address and part number selection). This allows two of the same devices to be connected to the same I2C bus. Both versions support standard, fast, and high speed I2C interface modes. The AD7999 comes in one version.

The AD7991/AD7995/AD7999 normally remain in a shutdown state, powering up only for conversions. The conversion process is controlled by a command mode, during which each I2C read operation initiates a conversion and returns the result over the I2C bus.

When four channels are used as analog inputs, the reference for the part is taken from VDD; this allows the widest dynamic input range to the ADC. Therefore, the analog input range to the ADC is 0 V to VDD. An external reference, applied through the VIN3/VREF input, can also be used with this part.

Applications

System Monitoring
Battery Powered Systems
Data Acquisition
Medical Instruments

01 Oct 2012 09:58 · Dragos Bogdan

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 different microcontroller platforms.

Driver Description

The driver contains two parts:

The driver for the AD799x 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 AD799x driver can be used exactly as it is provided.

There are three functions which are called by the AD799x driver:

I2C_Init() – initializes the communication peripheral.
I2C_Write() – writes data to the device.
I2C_Read() – reads data from the device.

I2C driver architecture

The following functions are implemented in this version of AD799x driver:

Function	Description
char AD799x_Init(char partNumber, char deviceVersion)	Initializes I2C.
void AD799x_SetConfigurationReg(unsigned char registerValue)	Writes data into the Configuration Register.
void AD799x_GetConversionResult(short* convValue, char* channel)	Reads the High byte and the Low byte of the conversion.
float AD799x_ConvertToVolts(short rawSample, float vRef)	Converts a raw sample to volts.

01 Oct 2012 14:59 · Dragos Bogdan

HW Platform(s):

Digilent Cerebot MX3cK (Digilent)
Cerebot MC7 (Digilent)

Downloads

AD7991 DSPIC33 Driver
AD7991 chipKIT Driver
AD799x Driver: https://github.com/analogdevicesinc/no-OS/tree/master/drivers/adc/ad799x
PmodAD2 Demo for PIC32MX320F128H: https://github.com/analogdevicesinc/no-OS/tree/master/Microchip/PIC32MX320F128H/PmodAD2
PIC32MX320F128H Common Drivers: https://github.com/analogdevicesinc/no-OS/tree/master/Microchip/PIC32MX320F128H/Common

Digilent Cerebot MX3cK Quick Start Guide

This section contains a description of the steps required to run the AD7991 demonstration project on a Digilent Cerebot MX3cK platform.

Required Hardware

Cerebot MX3cK (Digilent)
PmodAD2 (Digilent)

Required Software

MPLAB X Integrated Development Environment
MPLAB XC32 compiler
The AD7991 demonstration project for PIC32MX320F128H.

The AD7991 demonstration project for PIC32MX320F128H consists of three parts: the AD799x Driver, the PmodAD2 Demo for PIC32MX320F128H and the PIC32MX320F128H Common Drivers.

All three parts have to be downloaded.

Hardware Setup

A PmodAD2 has to be connected to the J2 connector of Cerebot MX3cK development board.

Using JP1 jumper you can either have 4 input channels or 3 input channels.

Reference Project Overview

The following commands were implemented in this version of AD7991 reference project for Cerebot MX3cK board.

Command	Description
help?	Displays all available commands.
voltage?	Initiates a conversion and displays the captured voltage for selected channel. Accepted values: 0..3 - selected channel.
register?	Initiates a conversion and displays the data register in decimal format for selected channel. Accepted values: 0..3 - selected channel.

Commands can be executed using a serial terminal connected to the UART1 peripheral of PIC32MX320F128H.

The following image shows a generic list of commands in a serial terminal connected to processor’s UART peripheral.

The reference voltage for the AD7991 is the supply voltage which is 3.3V.

Software Project Setup

This section presents the steps for developing a software application that will run on the Digilent Cerebot MX3cK development board for controlling and monitoring the operation of the ADI part.

Run the MPLAB X integrated development environment.
Choose to create a new project.
In the Choose Project window select Microchip Embedded category, Standalone Project and press Next.

In the Select Device window choose PIC32MX320F128H device and press Next.

In the Select Tool window select the desired hardware tool and press Next.

In the Select Compiler window chose the XC32 compiler and press Next.

In the Select Project Name and Folder window choose a name and a location for the project.

After the project is created, all the downloaded source files have to be copied in the project folder and included in the project.

The project is ready to be built and downloaded on the development board.

05 Jul 2012 14:45