This version (09 Oct 2012 09:05) was approved by DragosB.The Previously approved version (28 Sep 2012 16:48) is available.

AD7091R - No-OS Driver for Microchip Microcontroller Platforms

Supported Devices

AD7091R

Evaluation Boards

PmodAD6

Overview

The AD7091R is a 12-bit successive approximation analog-to-digital converter (ADC) that offers ultralow power consumption (typically 349 µA at 3 V and 1 MSPS) while achieving fast throughput rates (1 MSPS with a 50 MHz SCLK). The AD7091R uses advanced design and process techniques to achieve this very low power dissipation at high throughput rates. The part also features an on-chip, accurate 2.5 V reference.

Operating from a single 2.7 V to 5.25 V power supply, the part contains a wide bandwidth track-and-hold amplifier that can handle input frequencies in excess of 7 MHz. The AD7091R also features an on-chip conversion clock and high speed serial interface. The conversion process and data acquisition are controlled using a CONVST signal and an internal oscillator.

Applications

Instrumentation and Measurement
- Battery and USB powered systems
  - Data acquisition systems
  - Handheld meters
- Field Instruments
Consumer
- Battery powered devices
Communications
- Optical systems
- Mobile communications

28 Sep 2012 15:55 · 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 AD7091R 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 AD7091R driver can be used exactly as it is provided.

There are three functions which are called by the AD7091R driver:

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

SPI driver architecture

The following functions are implemented in this version of AD7091R driver:

Function	Description
unsigned char AD7091R_Init(void)	Initializes the SPI communication peripheral.
void AD7091R_SoftwareReset(void)	Initiate a software reset of the device.
unsigned short AD7091R_ReadSample(void)	Initiates one conversion and reads back the result.
void AD7091R_PowerDown(void)	Puts the device in power-down mode.
void AD7091R_PowerUp(void)	Powers up the device.
float AD7091R_ConvertToVolts(short rawSample, float vRef)	Converts a 12-bit raw sample to volts.

28 Sep 2012 16:38 · Dragos Bogdan

HW Platform(s):

Downloads

Digilent Cerebot MX3cK Quick Start Guide

This section contains a description of the steps required to run the AD7091R demonstration project on a Digilent Cerebot MX3cK platform.

Required Hardware

Cerebot MX3cK (Digilent)
PmodAD6

Required Software

Hardware Setup

A PmodAD6 has to be connected to the JE connector of Cerebot MX3cK development board.

Reference Project Overview

Following commands were implemented in this version of AD7091R reference project for Cerebot MX3cK board.

Command	Description
help?	Displays all available commands.
reset=	Initiates a software reset. Accepted value: 1.
power=	Powers up or down the device. Accepted values: 0 - 1.
voltage?	Initiates a conversion and displays the captured voltage.
register?	Initiates a conversion and displays the raw data in decimal format.

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

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

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, the 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