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AD7124-8 pmod软件用户指南

消耗积分:3 | 格式:pdf | 大小:3.96MB | 2021-03-22

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This version (25 Sep 2020 13:48) was approved by Andrei Drimbarean.

Table of Contents

AD7124-8 PMOD EVAL_ADICUP3029 Demo (w/ EVAL-AD7124-8-PMDZ)

The ADuCM3029_demo_ad7124_8PMDZ project provides a solution to control the AD7124-8 ADC on the EVAL-AD7124-8-PMDZ PMOD using a simple CLI on the USB. The demo showcases the flexibility of the AD7124 in choosing inputs, filters and different ranges for the available 16 channels.

General Description/Overview

The EVAL-AD7124-8-PMDZ is a minimalist 8-Channel, Low Noise, Low Power, 24-Bit, Sigma-Delta ADC (Analog to Digital Converter) with PGA and Reference, SPI Pmod board for the AD7124-8. This module is designed as a low-cost alternative to the fully-featured AD7124-8 evaluation board and has no extra signal conditioning for the ADC.

The initial configuration of the ADuCM3029_demo_ad7124_8PMDZ engages all inputs in a mix of differential and single-ended channels. The input assignation to channels is the following:

  • Channel 0: AIN0-AIN1, differential;
  • Channel 1: AIN2-AIN3, differential;
  • Channel 2: AIN4-AIN5, differential;
  • Channel 3: AIN6-AIN7, differential;
  • Channel 4: AIN8-AIN9, differential;
  • Channel 5: AIN10-AIN11, differential;
  • Channel 6: AIN12-AIN13, differential;
  • Channel 7: AIN14-AIN15, differential;
  • Channel 8: AIN0-AGND, single-ended;
  • Channel 9: AIN1-AGND, single-ended;
  • Channel 10: AIN2-AGND, single-ended;
  • Channel 11: AIN3-AGND, single-ended;
  • Channel 12: AIN4-AGND, single-ended;
  • Channel 13: AIN5-AGND, single-ended;
  • Channel 14: AIN6-AGND, single-ended;
  • Channel 15: AIN7-AGND, single-ended;

By default only channel 0 is active at first, but this can be adjusted using the appropriate CLI commands (described below). At first all channels are using the configuration register 0 which is set to sinc4 filter option and the first option of PGA corresponding to the widest range. The filter sample rate is set at maximum. Each configuration register has a different PGA setting so that each channel can be set using the CLI to any PGA. The demo does this by assigning each channel to the corresponding configuration register that contains the desired PGA setting. Most of the demo CLI commands work in this configuration, but the CLI also offers access to the individual registers for the user to set the desired configuration manually.

Demo Requirements

The following is a list of items needed in order to replicate this demo.

  • Hardware
    • EVAL-ADICUP3029
    • EVAL-AD7124-8-PMDZ
    • Mirco USB to USB cable
    • PC or Laptop with a USB port
  • Software

Setting up the Hardware

  1. Connect EVAL-AD7124-8-PMDZ board to the EVAL-ADICUP3029.
  2. Connect a micro-USB cable to P10 connector of the EVAL-ADICUP3029 and connect it to a computer. The final setup should look similar to the picture below.

Configuring the Software

The software needs no configuration.

Outputting Data

A serial terminal is an application that runs on a PC or laptop that is used to display data and interact with a connected device (including many of the Circuits from the Lab reference designs). The device's UART peripheral is most often connected to a UART to USB interface IC, which appears as a traditional COM port on the host PC/ laptop. (Traditionally, the device's UART port would have been connected to an RS-232 line driver / receiver and connected to the PC via a 9-pin or 25-pin serial port.) There are many open-source applications, and while there are many choices, typically we use one of the following:

Before continuing, please make sure you download and install one of the above programs.

There are several parameters on all serial terminal programs that must be setup properly in order for the PC and the connected device to communicate. Below are the common settings that must match on both the PC side and the connected UART device.

  1. COM Port - This is the physical connection made to your PC or Laptop, typically made through a USB cable but can be any serial communications cable. You can determine the COM port assigned to your device by visiting the device manager on your computer. Another method for identifying which COM port is associated with a USB-based device is to look at which COM ports are present before plugging in your device, then plug in your device, and look for a new COM port.
  2. Baud Rate - This is the speed at which data is being transferred from the connected device to your PC. These parameters must be the same on both devices or data will be corrupted. The default setting for most of the reference designs in 115200.
  3. Data Bits - The number of data bits per transfer. Typically UART transmits ASCII codes back to the serial port so by default this is almost always set to 8-Bits.
  4. Stop Bits - The number of “stop” conditions per transmission. This usually set to 1, but can be set to 2 for redundancy.
  5. Parity - Is a way to check for errors during the UART transmission. Unless otherwise specified, set parity to “none”.
  6. Flow Control - Is a way to ensure that data lose between fast and slow devices on the same UART bus are not lost during transmission. This is typically not implemented in a simple system, and unless otherwise specified, set to “none”.

In many instances there are other options that each of the different serial terminal applications provide, such as local line echo or local line editing, and features like this can be turned on or off depending on your preferences. This setup guide will not go over all the options of each tool, but just the minor features that will make it easier to read back data from the connected devices.

Example setup using Putty

  1. Plug in your connected device using a USB cable or other serial cable.
  2. Wait for the device driver of the connected device to install on your PC or Laptop.
  3. Open your device manager, and find out which COM port was assigned to your device.
  4. Open up your serial terminal program (Putty for this example)
  5. Click on the serial configuration tab or window, and input the settings to match the requirements of your connected device. The default baud rate for most of the reference designs is 115200. Make sure that is the selected baud rate as well.
  6. Ensure that local echo and line editing are enabled, so that you can see what you type and are able to correct mistakes. (Some devices may echo typed characters - if so, you will see each typed character twice. If this happens, turn off local echo.)
  7. Click on the open button, and as long as your connected device and serial terminal program are setup the same, than you should see data displaying.
Hint: If you see nothing in the serial terminal, try hitting the reset button on the embedded development board.

Available commands

Typing help or h after initial calibration sequence will display the list of commands and their short versions. Bellow is the short command list:

Function Command Description Example
General commands
Help h Display available commands.
Reset rst Reset the application.
<opt> = 'dev' to perform only a device reset; do not include to perform an application reset. 		rst dev - perform only device reset (datasheet defaults);
rst - perform application reset (application defaults).
ADC commands
Register read arr Read an ADC register of a specific address.
<addr> = Address of the register to be read in hexadecimal base. 		arr 2a - Read register 0x2A
Register write awr Write an ADC register of a specific address with a new value.
<addr> = Address of the register to be written in hexadecimal base.
<val> = New value of the register. 		arw 9 8002 - Write 0x8002 to register 0x9.
Get data ags Get a number of samples per enabled channels. If the operation takes too long press 'q' to abort.
<no> = Number of samples (maximum 2048). If sample rate is smaller than 3000 setting the argument 0 or no argument means continuous streaming.
Enable channels aces Choose ADC channels to be activated.
<mask> = 16-bit mask of the channels to be activated. Can be hexadecimal or binary.
A bit of 1 means activated the channel, a bit of 0 means deactivate
the channel. 		aces 0xAAAA - activate every other channel. '0x' is necessary for hexadecimal interpretation.
Get enabled channels aceg Get enable status of ADC channels. Returns a hexadecimal 16-bit mask where bits of 1 represent enabled channels, and bits of 0 represent disabled channels.
Set PGA aps Set PGA for a channel.
<chan> = ID of the channel to be changed.
<opt> = PGA option; values are: opt0, opt1, … opt7 corresponding to the datasheet. 		aps 0 opt3 - set ADC channel 0 to PGA 3, gain value of 8.
Get PGA apg Display a channel's PGA option; return values are: opt0, opt1, … opt7 corresponding to the datasheet.
<chan> = ID of the channel to be read. 		apg 0 - read the PGA value of channel 0.
Set sample
rate 		aos Set ADC sample rate. Filter option, power mode and reference clock must be taken into consideration.
<odr> = New sample rate value. 		aos 2000 - set sample rate to 2000 samples per second.
Get sample rate aog Read the current sample rate.
Set filter
option 		afs Set ADC filter option.
<opt> = filter option; can be: 'sinc4', 'sinc3', 'fflt4', 'fflt3' and 'postf'.
<post> = post-filter option; can be: 'opt0', 'opt1', … 'opt3'; add only when opt=postf. 		afs fflt4 - set filter option to fast settling sinc4.
Get filter
option 		afg Read the current filter.

Obtaining the Source Code

We recommend not opening the project directly, but rather import it into CrossCore Embedded Studios and make a local copy in your workspace.

The source code and include files of the ADuCM3029_demo_ad7124_8PMDZ can be found here:

ADuCM3029_demo_ad7124_8PMDZ at Github

How to use the Tools

The official tool we promote for use with the EVAL-ADICUP3029 is CrossCore Embedded Studio. For more information on downloading the tools and a quick start guide on how to use the tool basics, please check out the Tools Overview page.

Importing

For more detailed instructions on importing this application/demo example into the CrossCore Embedded Studios tools, please view our How to import existing projects into your workspace section.

Debugging

For more detailed instructions on importing this application/demo example into the CrossCore Embedded Studios tools, please view our How to configure the debug session section.

Project Structure

The application contains the platform drivers with the sources in platform_source and the headers in platform_include. In the src root directory there is the ad7124 driver as found on Github, but with a custom initialization vector in ad7124_regs module.

End of Document

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