AD5668-微控制器无操作系统驱动程序

消耗积分:2 | 格式:pdf | 大小:1.48MB | 2021-05-21

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This version (25 Jan 2021 05:41) was approved by Robin Getz.The Previously approved version (25 Jan 2021 05:23) is available.

AD5668 - Microcontroller No-OS Driver

Supported Devices

AD5668

Evaluation Boards

Overview

The AD5668 device is a low power, octal, 16-bit, buffered voltage-output DAC. The device operates from a single 2.7 V to 5.5 V supply and is guaranteed monotonic by design.

The AD5668 has an on-chip reference with an internal gain of 2. The AD5668-1 has an 1.25 V 5 ppm/°C reference, giving a full-scale output range of 2.5 V; the AD5668-2, -3 has a 2.5 V 5 ppm/°C reference, giving a full-scale output range of 5 V. The on-board reference is off at power-up, allowing the use of an external reference. The internal reference is enabled via a software write.

The part incorporates a power-on reset circuit that ensures that the DAC output powers up to 0 V (AD5668-1, -2) or midscale (AD5668-3) and remains powered up at this level until a valid write takes place. The part contains a power-down feature that reduces the current consumption of the device to 400 nA at 5 V and provides software-selectable output loads while in power-down mode for any or all DAC channels.

The outputs of all DACs can be updated simultaneously using the LDAC function, with the added functionality of user-selectable DAC channels to simultaneously update. There is also an asynchronous CLR that updates all DACs to a user-programmable code—zero scale, midscale, or full scale.

The AD5668 utilizes a versatile 3-wire serial interface that operates at clock rates of up to 50 MHz and is compatible with standard SPI®, QSPI™, MICROWIRE™, and DSP interface standards. The on-chip precision output amplifier enables rail-to-rail output swing.

The AD5668-EP supports defense and aerospace applicatons (AQEC)

Applications

Optical transceivers
Power Amp control
Data acquisition systems
Digital gain and offset adjustment

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 AD5668 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 AD5668 driver can be used exactly as it is provided. There are three functions which are called by the AD5668 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 AD5668 driver:

Function	Description
unsigned char AD5668_Init(void)	Initializes the SPI communication peripheral.
void AD5668_SetRegisterValue(unsigned short regValue)	Writes to the DAC register.

Downloads

Renesas RL78G13 Quick Start Guide

This section contains a description of the steps required to run the AD5668 demonstration project on a Renesas RL78G13 platform.

Required Hardware

Required Software

Hardware Setup

An EVAL-AD5668EBZ has to be interfaced with the Renesas Demonstration Kit (RDK) for RL78G13:

  EVAL-AD5668SDZ connector J5 SYNC  →  YRDKRL78G13 J11 connector Pin 1
  EVAL-AD5668SDZ connector J7 DIN   →  YRDKRL78G13 J11 connector Pin 2
  EVAL-AD5668SDZ connector J6 SCLK  →  YRDKRL78G13 J11 connector Pin 4

Software Setup

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

CSI10 (Clocked Serial Interface 10) – For the ADI 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 reference project generates an 1 Hz sine wave on all channels.

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