UM-26000-A
DT7837
User’s Manual
Title Page
Copyright Page
First Edition
March, 2015
Data Translation, Inc.
100 Locke Drive
Marlboro, MA 01752-1192
(508) 481-3700
www.datatranslation.com
Fax: (508) 481-8620
E-mail: info@datx.com
Copyright © 2015 by Data Translation, Inc.
All rights reserved.
Information furnished by Data Translation, Inc. is believed to be
accurate and reliable; however, no responsibility is assumed by
Data Translation, Inc. for its use; nor for any infringements of
patents or other rights of third parties which may result from its
use. No license is granted by implication or otherwise under any
patent rights of Data Translation, Inc.
Use, duplication, or disclosure by the United States Government
is subject to restrictions as set forth in subparagraph (c)(1)(ii) of
the Rights in Technical Data and Computer software clause at 48
C.F.R, 252.227-7013, or in subparagraph (c)(2) of the Commercial
Computer Software - Registered Rights clause at 48 C.F.R.,
52-227-19 as applicable. Data Translation, Inc., 100 Locke Drive,
Marlboro, MA 01752.
The DT7837 software is based of the Linux open-source
development environment which uses the GNU (General Public
License). Data Translation example programs may use code from
other vendors. This code is for demonstration purposes only. If
you want to use this code for commercial purposes, you must
ensure that you resolve any licensing issues with the appropriate
parties.
Data Translation® is a registered trademark of Data Translation,
Inc.
All other brand and product names are trademarks or registered
trademarks of their respective companies.
Radio and Television Interference
This equipment has been tested and found to comply with CISPR EN55022 Class A and
EN61000-6-1 requirements and also with the limits for a Class A digital device, pursuant to
Part 15 of the FCC Rules. These limits are designed to provide reasonable protection against
harmful interference when the equipment is operated in a commercial environment. This
equipment generates, uses, and can radiate radio frequency energy and, if not installed and
used in accordance with the instruction manual, may cause harmful interference to radio
communications. Operation of this equipment in a residential area is likely to cause harmful
interference, in which case the user will be required to correct the interference at his own
expense.
Changes or modifications to this equipment not expressly approved by Data Translation could
void your authority to operate the equipment under Part 15 of the FCC Rules.
Note: This product was verified to meet FCC requirements under test conditions that
included use of shielded cables and connectors between system components. It is important
that you use shielded cables and connectors to reduce the possibility of causing interference
to radio, television, and other electronic devices.
FCC Page
Canadian Department of Communications Statement
This digital apparatus does not exceed the Class A limits for radio noise emissions from
digital apparatus set out in the Radio Interference Regulations of the Canadian Department of
Communications.
Le présent appareil numérique n’émet pas de bruits radioélectriques dépassant les limites
applicables aux appareils numériques de la class A prescrites dans le Règlement sur le
brouillage radioélectrique édicté par le Ministère des Communications du Canada.
Table of Contents
Table of Contents
About this Manual . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Intended Audience. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
How this Manual is Organized . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Conventions Used in this Manual . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Related Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Where To Get Help. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Chapter 1: Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Hardware Features. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Board Layout Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Supported Software . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
Supported Accessories. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Getting Started Procedure. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
Chapter 2: Principles of Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
Block Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
ARM Block. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
ARM Processor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
Memory . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
Embedded NAND Flash . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
EEPROM. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
Micro SD Card . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
USB Device (Client) Port . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
USB Host Port . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
Serial Port 0 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
Serial Port 1 / I2C2 Port . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
SPI Port . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
GPMC Bus Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
Additional Signals Used on Processor. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
Digital Connector . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
Analog Input Features. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
Analog Input Channels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
Input Ranges and Gains. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
IEPE Functions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
Input Resolution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
Continuous Sampling Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
Input Triggers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
Input Clock Source and Sampling Frequency. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
Data Format and Transfer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
5
Contents
Error Conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
Tachometer Input Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
General-Purpose Counter/Timer Features. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
C/T Channels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
C/T Clock Input Sources . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
Gate Types . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
Pulse Output Period, Pulse Width, and Polarity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
Counter/Timer Operation Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
Event Counting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
Rate Generation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
Non-Repeatable One-Shot . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
Idle Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
Measure Counter Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
Digital I/O Features. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
Digital I/O Lines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
Operation Modes. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
Triggering Acquisition on Multiple Modules . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
Chapter 3: Troubleshooting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49
Technical Support . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50
If Your Module Needs Factory Service . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
Chapter 4: Calibration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53
Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54
Using the Calibration Utility . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55
Calibrating the Analog Input Subsystem . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56
Warming up the Module . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56
Connecting a Precision Voltage Source . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56
Using the Auto-Calibration Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56
Using the Manual Calibration Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57
Restoring Factory-Calibration Settings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58
Appendix A: Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59
Analog Input Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60
Digital Input Specifications. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63
Digital Output Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64
Tachometer Input Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65
Measure Counter Specifications. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66
General-Purpose Counter/Timer Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67
Trigger Specifications. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68
Master Oscillator Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69
Power, Physical, and Environmental Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70
6
Regulatory Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71
Connector Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72
External Power Supply Specifications. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73
Appendix B: Connector Pin Assignments and LED Status Indicators . . . . . . . . . . 75
Analog Input Connectors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76
Digital Connector . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77
USB Device (Client) Connector . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79
USB Host Connector . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80
Ethernet Connector . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81
Micro SD Card Connector. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82
External +5 V Power Connector. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83
Serial Connectors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85
Serial Port 0 (UART 0) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85
SPI Connector . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86
Serial Port 1 / I
2
C2 Connector. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87
I/O Block Connector . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88
STP26 Screw Terminal Panel. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91
LED Status Indicators . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93
Contents
Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95
7
Contents
8
The first part of this manual describes how to install and set up your DT7837 module and
verify that your module is working properly.
The second part of this manual describes the features of the DT7837 module and how to
program the DT7837 module using Linux system calls. Troubleshooting information is also
provided.
Intended Audience
This document is intended for engineers, scientists, technicians, or others responsible for
using and/or programming a DT7837 module for data acquisition operations in the Linux
operating system. It is assumed that you have some familiarity with data acquisition
principles and that you understand your application.
How this Manual is Organized
This manual is organized as follows:
• Chapter 1, “Overview,” describes the major features of the DT7837 module, as well as the
supported software and accessories for the module.
About this Manual
• Chapter 2, “Principles of Operation,” describes all of the features of the DT7837 module.
• Chapter 3, “Troubleshooting,” provides information that you can use to resolve problems
with the DT7837 module should they occur.
• Chapter 4, “Calibration,” describes how to calibrate the analog circuitry of the DT7837
module.
• Appendix A, “Specifications,” lists the specifications of the DT7837 module.
• Appendix B, “Connector Pin Assignments and LED Status Indicators,” lists the pin
assignments of the connectors on the DT7837 module, and describes the LED status
indicators on the DT7837 module.
• An index completes this manual.
Conventions Used in this Manual
The following conventions are used in this manual:
• Notes provide useful information or information that requires special emphasis, cautions
provide information to help you avoid losing data or damaging your equipment, and
warnings provide information to help you avoid catastrophic damage to yourself or your
equipment.
• Items that you select or type are shown in bold.
9
About this Manual
Related Information
Where To Get Help
Refer to the following documents, which can be found on the DT7837 web page on our
website (http://www.datatranslation.com/products/dataacquisition/embedded/DT7837/)
for more information on using the DT7837 module:
• DT7837 Getting Started help file
• DT7837 File I/O Programming Manual
Refer to your Linux documentation for more information about Linux and Texas Instruments
documentation for more information on the TI Sitara AM3352, 1 GHz, ARM® Cortex-A8
processor.
Should you run into problems installing or using a DT7837 module, the Data Translation
Technical Support Department is available to provide technical assistance. Refer to Chapter 4
for more information. If you are outside the United States or Canada, call your local
distributor, whose number is listed on our web site (www.datatranslation.com).
10
1
Overview
Hardware Features. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Supported Software . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
Supported Accessories. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Getting Started Procedure. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
11
Chapter 1
Hardware Features
The DT7837 module is an open-source Linux computing platform with a high-accuracy,
dynamic signal analyzer front-end, making it ideal for embedded applications that require
noise, vibration, and acoustic measurements.
The module is composed of two boards (the bottom board contains the ARM block and the
top board contains the I/O block) that connect together, as show in Figure 1. Users can embed
the module into their own enclosure and/or system, as needed.
12
Figure 1: DT7837 Module
The key features of the DT7837 module are as follows:
• Open-source computing platform featuring a TI Sitara AM3352, 1 GHz, ARM® Cortex-A8
processor.
• Linux distribution consisting of a Linux kernel, bootloader, and file system with a DT7837
device driver, USB device (client) driver, and USB host driver.
• Ethernet 10/100 Mbps connectivity to a host computer.
• USB 2.0 full-speed connectivity to a host computer.
• USB 2.0 host connection to external devices, such as a mouse, keyboard, or external
storage devices.
• Analog input subsystem:
− Four, single-ended analog input channels available through SMA connectors.
− Four simultaneous sampling, Delta-Sigma, 24-bit analog-to-digital converters (ADCs).
− Support for IEPE (Integrated Electronic Piezoelectric) inputs, including use of a 4 mA
current source with 20 V compliance voltage for AC or DC coupling.
− Programmable throughput rate from 195.3125 Samples/s to 105.469 kSamples/s.
− Input range of ±10 V with software-selectable gains of 1 and 10 for an effective input
range of ±10 V and ±1 V.
− Continuous acquisition from multiple analog input channels simultaneously.
− Supports the ability to return the value of the tachometer, general-purpose
counter/timer, measure counter, and/or digital input port in the analog input data
stream, allowing you to measure a variety of signals synchronously with analog input
measurements.
− Software-programmable trigger source (software trigger, external trigger, or threshold
trigger using any analog input channel) to start acquisition.
Overview
− Accounts for analog input group delay in hardware and allows user-specified trigger
delay to account for analog output group delay.
• Up to eight, TTL digital input lines using the eight general-purpose inputs. You can read
the digital input port directly or you can return the value of the digital input port in the
input data stream.
• Up to eight, TTL digital output lines using the eight general-purpose outputs. You can
write a value to the digital output port directly.
• One, 32-bit, general-purpose counter/timer for performing event counting, rate
generation, and non-repeatable one-shot operations. You can use two general-purpose
input signals for the C/T clock and gate inputs and one general-purpose output signal for
the C/T clock output. You can read the value of the counter/timer directly or through the
input data stream.
• One tachometer input signal. The value of the tachometer input signal can be returned in
the input stream.
• One phase/measure counter. You can program the edge that starts the measurement and
the edge that stops the measurement. Many edge types are supported. The data from the
measure counter can be returned in the input stream.
• 2 GB embedded NAND flash memory that contains the Linux kernel, bootloader, and file
system; this memory can also be used to store user files and data
• 512 MB SDRAM (DDR3) memory
• 8 kBytes EEPROM
• Micro SD connector supports micro SD cards, which can be used as a boot source for
general-purpose file and data storage
• 3.3 V UART, I2C, and an SPI (Serial Peripheral Interface) interfaces for embedded
connectivity.
13
Chapter 1
• Serial debug port.
• External power connectors (4-pin DIN or 3-pin Phoenix header) for connecting a +5 VDC
power supply.
14
Board Layout Overview
The DT7837 module consists of an ARM block and a I/O block. Figure 2 shows the layout of
the ARM block (the bottom board). Figure 3 shows the layout of the I/O block (the top board).
Overview
15
Chapter 1
Digital Connector
(Tachometer, Digital I/O, External Trigger, Counter/Timer)
Power L ED
Ethernet
Connector
USB Host
Port
USB Device
(Client) Port
SD Card
+5 V Power
AM3552
Processor
Reset/Boot
Switch
Connector to the
I/O Block
Serial
Port 1
(J14)
Serial
Port 0
(J13)
SPI
Port
(J12)
Grounding
Stud
16
Figure 2: Layout of the ARM Block of the DT7837 Module
Overview
Output Trigger
LED (bottom)
Input Trigger LED
(top)
Analog Output Connector
(analog output currently not
supported in software)
Analog Input Connectors
Figure 3: Layout of the I/O Block of the DT7837 Module
17
Chapter 1
Supported Software
The following software is available for use with the DT7837 module:
• DT7837 File I/O Commands – A set of commands in Linux user space for opening a
subsystem or stream, configuring a subsystem or stream, acquiring data in the input
stream, reading or updating the digital I/O port, and/or writing values to the calibration
potentiometers. Numerous example programs are provided to illustrate how to use these
commands. Refer to the DT7837 File I/O Programming Manual for more information.
• DT7837 Kernel Device Driver – The device driver resides in the Linux kernel and is
responsible for performing the functions defined by the DT7837 file I/O commands on the
DT7837 module.
• DT7837 Calibration Utility – This utility, described in Chapter 4, allows you to calibrate
the analog circuitry of the DT7837 module.
18
Supported Accessories
The following optional accessories are available for a DT7837 module:
• STP26 screw terminal panel – This screw terminal panel accepts tachometer, digital
input, C/T gate input, and C/T clock input signals from the Digital connector on the
DT7837 module and provides digital output and C/T clock output signals from the
Digital connector on the module.
The 26-pin, 36-inch, EP406 cable is included with the STP26 screw terminal panel. The
cable allows you to attach the STP26 screw terminal panel to the Digital connector on a
DT7837 module.
Figure 4 shows the STP26 and EP406 cable.
Overview
Figure 4: STP26 Screw Terminal Panel and EP406 Cable
• EP405 USB to Serial TTL Debug Cable – This 3Mbaud, 1.8 m cable, shown in Figure 5,
connects the USB port of the host computer to serial UART connector J13 on the DT7837,
allowing you to debug the DT7837 using a terminal interface.
Figure 5: EP405 USB to Serial TTL Debug Cable
19
Chapter 1
• EP361 External Power Supply – This +5 VDC optional power supply and cable, shown in
Figure 6, connects to the DIN power connector on the DT7837 module and to the wall
power outlet.
Figure 6: EP361 +5 VDC External Power Supply
20
Getting Started Procedure
Refer to the DT7837 Getting Started help file on our web site
(http://www.datatranslation.com/products/dataacquisition/embedded/DT7837/) for
getting started information
Overview
21
Chapter 1
22
2
Principles of Operation
Block Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
Analog Input Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
Tachometer Input Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
General-Purpose Counter/Timer Features. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
Measure Counter Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
Digital I/O Features. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
Triggering Acquisition on Multiple Modules . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
23
Chapter 2
Serial
UART
Ethernet
10/100
USB 2.0
Host
USB 2.0
Client
SD Card
DT7837 Block Diagram
Four 24-Bit
A/D Inputs
I/O B loc k
DRAM
512 MB DDR 3
TI
AM335x
ARM Cortex-A8
Clock G e n e rato rs
Voltage Regulators
ARM Block
GPMC
Bus
NAND Flash 2GB
Expansion
Bus
26-Pin D i gita l
Connector
IEPE Inp u ts
GP IO Sign a ls
(8 DI, 8 DO,
Measure Counter,
Counter/Timer,
Ext. T rig g e r In p u t)
Tachometer
FPGA
FIFOs
Power Supply
+5 VDC
24-Bit
D/A Output
Stim ulus
Waveform
Output*
*Currently, not supported in software.
Block Diagram
The DT7837 is an open-source Linux computing platform with a high-accuracy, dynamic
signal analyzer front-end.
The DT7837 consists of two boards. The bottom board is the ARM block, which includes the
ARM processor, PC and embedded connectivity options, and memory, as well as the digital
I/O, counter/timer, measure counter, and tachometer circuitry.
The top board is the I/O block, which includes four 24-bit IEPE analog inputs and one 24-bit
stimulus analog output.
Note: The analog output circuitry is currently not supported in software.
Figure 7 shows a block diagram of the DT7837 module.
24
Figure 7: Block Diagram of the DT7837 Module
ARM Block
The ARM block of the DT7837 module uses the TI Sitara AM3352 processor and its associated
peripherals to provide an open-source, single-board computer. The AM3352 supports many
different interfaces, many of which are shared on the configurable I/O pins. In addition to the
AM3352, the DT7837 module uses an embedded NAND flash and an FPGA.
This section describes the features of the ARM block in more detail.
ARM Processor
The AM3352 is based on the ARM Cortex-8 32-bit processor and is configured to run at
600 MHz.
Refer to the following web site for more information on this processor:
http://www.ti.com/product/am3352
Memory
Principles of Operation
A 512 MB, DDR3, SDRAM memory device is connected to the AM3352 processor through a
dedicated DDR (Double Data Rate) memory interface.
Embedded NAND Flash
A 2 GB embedded NAND flash device is connected to the AM3352 processor through the
16-bit GPMC (General Purpose Memory Controller) bus, and can be accessed at the CS0
address space. The flash memory contains the Linux kernel, bootloader, and the file system.
You can also use the flash memory for general-purpose data and file storage as well as for
input data and waveform storage.
EEPROM
An 8 kByte EEPROM device is connected to the I2C0, 2-wire, serial interface of the AM3352
processor. The EEPROM stores information about the device, including the calibration
information.
25
Chapter 2
Micro SD Card
A micro SD card slot is provided to support optional high-speed (up to 24 MB/s) micro SD
cards. Micro SD cards (not provided with the module) communicate with the AM3352
processor using the MMC0 port in the 4-bit interface mode.
You can use a micro SD card as a boot source or for general-purpose file and data storage.
USB Device (Client) Port
The DT7837 module provides a USB 2.0 device (client) port on a type B receptacle. The device
port connects to the USB port 0 controller of the AM3352 processor.
When connected to a host computer through this USB port, the host computer can identify the
DT7837 module and load the appropriate drivers through the enumeration process.
USB Host Port
The DT7837 provides a high-speed USB 2.0 host port on a type A receptacle. The host port
connects to the USB port 1 controller of the AM3352 processor. The USB host port supports
any USB device, provided that the required software is installed on the Linux operating
system.
If desired, you can connect USB devices, such as a keyboard, mouse, memory stick, or hub to
this port.
Serial Port 0
Serial port 0 is a 3.3 V TTL serial interface provided on a 6-pin header. This port supports
transmit and receive signals (no handshaking), and connects to the UART 0 interface of the
AM3552 processor.
This port is particularly useful when you are debugging your applications. To use this port,
use the EP405 USB to serial TTL adapter cable.
Serial Port 1 / I2C2 Port
Serial port 1 and the I2C2 port are provided on the same 6-pin header.
Serial port 1 is a 3.3 V TTL serial interface that supports transmit and receive signals, and
connects to the UART1 interface of the AM3552 processor.
The bidirectional I
provided for embedded connectivity. It is possible to reconfigure the pins of the I
interface as the remaining UART 1 pins to provide the full functionality of serial port 1.
2
C2 port connects to the I2C port 2 interface of the AM3552 processor and is
2
C port 2
26
SPI Port
The SPI (Serial Peripheral Interface) is provided on an additional 6-pin header for embedded
connectivity. This port connects to the SPI port 1 interface of the AM3552 processor.
GPMC Bus Interface
A 16-bit address/data multiplexed bus interface is supplied by the processor. In addition to
the NAND flash, this bus also supports the FPGA. All control registers for the DT7837 are
accessible in the CS1 address space. The CS3 address space provides access to the input FIFO.
Additional Signals Used on Processor
The following are additional pins on the processor that are connected for use on the DT7837
module:
• XDMAEvent0 – Configured, but not used
• XDMAEvent1 – Used for an analog output DMA event (currently not supported)
• XDMAEvent2 – Used for an analog input DMA event
Principles of Operation
• GPIO1_20 – Configured for a DMA event, but not used
• GPIO1_25 – Configured as an interrupt, but not used
• GPIO1_26 – Configured as an interrupt, but not used
• GPIO1_27 – Configured as an interrupt, but not used
• GPIO3_20 – Configured as an interrupt, but not used
Digital Connector
The Digital connector provides access to the tachometer input and GPIO (General Purpose
Input and Output) signals of the DT7837 module. Refer to page 77 for the pin assignments of
this connector.
Using software, you can specify a general-purpose input signal as the signal source for the
following destinations:
• Digital input (the default signal for each general-purpose input pin)
• External A/D trigger input
• External D/A trigger input
• Gate input for the general-purpose counter/timer (C/T 0)
• Clock input for the general-purpose counter/timer (C/T 0)
27
Chapter 2
Using software, you can specify a general-purpose (general-purpose) output signal as the
signal source for one of these destinations:
• Digital output (the default signal for each general-purpose output pin)
• Clock output for the general-purpose counter/timer (C/T 0)
Note that a single general-purpose input may drive several destinations at the same time.
However, a single general-purpose output can have only one driving source.
28
Analog Input Features
This section describes the following features of analog input (A/D) subsystem on the DT7837
module:
• Analog input channels, described on this page
• Input ranges and gains, described on this page
• IEPE functions, described on page 30
• Input resolution, described on page 30
• Continuous sampling mode, described on page 30
• Input triggers, described on page 31
• Input sample clock source and sampling frequency, described on page 32
• Data format and transfer, described on page 33
• Error conditions, described on page 33
Analog Input Channels
Principles of Operation
The DT7837 module provides four analog input channels (channels 0 to 3). These are
single-ended channels; you can connect IEPE sensors to these inputs, if desired; refer to page
30 for more information on IEPE functions.
Note: To maintain simultaneous operation, all analog input connections on the DT7837
module must have the same lead lengths.
The DT7837 module uses four, Delta-Sigma, 24-bit ADCs that provide anti-aliasing filters
based on the clock rate. These filters remove aliasing, which is a condition where high
frequency input components erroneously appear as lower frequencies after sampling.
Using software, you can specify which analog input channels to sample by specifying bits 0 to
3 in the channel mask for the input stream.
Input Ranges and Gains
The DT7837 module provides an input range of ±10 V and software-selectable gains of 1 and
10. This provides effective input ranges of ±10 V (when the gain is 1) and ±1 V (when the gain
is 10).
29
Chapter 2
IEPE Functions
Applications that require accelerometer, vibration, noise, or sonar measurements often use
IEPE sensors. IEPE conditioning is built-in to the analog input circuitry of the DT7837 module.
The modules support the following software-programmable IEPE functions for each analog
input channel:
• Excitation current source – The DT7837 module provides an internal excitation current
source of 4 mA. You can turn the internal excitation current source on or off using
software.
• Coupling type – You can select whether AC coupling or DC coupling is used.
DT7837 modules provide +20 V compliance voltage.
Note: If you enable the use of the internal excitation current source, it is recommended that
you choose AC coupling.
Input Resolution
The resolution of the analog input channels is fixed at 24 bits; you cannot specify the
resolution in software.
Continuous Sampling Mode
The DT7837 module supports continuous sampling mode on the input stream. This is an
asynchronous I/O operation that is non-blocking so that your application can perform other
operations while acquisition is being performed.
In continuous sampling mode, you can acquire data from the following channels in the input
data stream: analog input channels 0 to 3, the tachometer input, the general-purpose
counter/timer, the measure counter, and the digital input port. In software, you specify the
channel mask for the input stream to determine which channels to sample. The bits of the
channel mask are as follows:
• Channels (bits) 0 to 3 – Analog input channels 0 to 3
• Channel (bit) 4 – Tachometer; refer to page 34 for more information
• Channel (bit) 5 – Counter/timer 0; refer to page 36 for more information
• Channel (bit) 6 – Measure counter; refer to page 43 for more information
• Channel (bit) 7 – Digital input port; refer to page 47 for more information
30
The trigger that starts acquisition for the channels in the input stream can be any of the
supported start trigger sources. Refer to page 31 for more information about the start trigger
sources. However, the input stream of the module must be armed (using software) before the
module can detect the trigger condition.
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