User's Guide

SBAU175A–July 2010– Revised August 2011

ADS1131REF and ADS1231REF

The ADS1131REF and the ADS1231REF are reference designs for delta-sigma analog-to-digital

converters (ADCs). The ADS1131REF contains the ADS1131 18-bit device, while the ADS1231REF

contains the ADS1231 24-bit device. Both systems contain all the circuitry and user interface elements

needed for a weigh-scale digitizer, and are meant as examples of a good design for a basic weigh-scale

system. Each system is also suitable for general evaluation of the respectively installed ADC. Throughout

this document, the term ADS1x31REF is used to refer to the common features and functions for both

systems.

The ADS1x31REF hardware has the following features:

• ADS1131 ADC for the ADS1131REF and ADS1231 ADC for the ADS1231REF

• Connections for load cells or other voltage sources

• Low-side excitation switch on the load cell header connector

• Ample EMI/RFI suppression between the ADC and rest of design

• Eight-digit starburst LCD readout

• USB connection for firmware updates and remote control

• Designed for very low power consumption

• Battery (9V) or wall power

Version 1.0.0 of the firmware includes the following features:

• Weigh-scale mode with two-point calibration

• Complete configuration of the device

• Real-time peak-to-peak and RMS noise calculation

• Autoranging voltage display

• Noise displayed in volts, codes, and bits

• Voltage displayed in volts or codes

• Adjustable averaging mode

• Raw hexadecimal code display

• Simple and fast configuration

• Parameters saved to internal flash memory

• Computer link

Graphical PC software is also provided for histogram display, datalogging, and device control.

We welcome bug reports and suggestions for additional features; please contact the Texas Instruments

Precision Analog Applications Group.

Hyperterm is a trademark of Microsoft Corporation.

Windows is a registered trademark of Microsoft Corporation.

All other trademarks are the property of their respective owners.

SBAU175A–July 2010–Revised August 2011 ADS1131REF and ADS1231REF

Submit Documentation Feedback

www.ti.com

Contents

1 Getting Started .............................................................................................................. 3

2 Weigh Scale Mode .......................................................................................................... 7

3 Analysis Mode ............................................................................................................. 11

4 Using the PC Software ................................................................................................... 14

5 Serial Console ............................................................................................................. 18

6 Hardware ................................................................................................................... 20

Appendix A Schematic and Layout ........................................................................................... 23

List of Figures

1 ADS1x31REF Controls and Connectors................................................................................. 3

2 4-Wire Load Cell to Terminal Block ...................................................................................... 4

3 6-Wire Load Cell to Terminal Block ...................................................................................... 5

4 4-Wire Load Cell to Header................................................................................................ 5

5 6-Wire Load Cell to Header................................................................................................ 5

6 ADS1231REF PC Software Display .................................................................................... 15

7 ADS1x31REF Average Data............................................................................................. 16

8 ADS1x31REF Hardware Block Diagram ............................................................................... 20

9 ADS1x31REF PCB—Top Side .......................................................................................... 25

10 ADS1x31REF PCB—Layer 1 ............................................................................................ 25

11 ADS1x31REF PCB—Layer 2 ............................................................................................ 26

12 ADS1x31REF PCB—Bottom Side ...................................................................................... 26

13 ADS1x31REF Schematic—ADC ........................................................................................ 27

14 ADS1x31REF Schematic—MCU ........................................................................................ 27

15 ADS1x31REF Schematic—USB......................................................................................... 28

List of Tables

1 Unit Conversion Factors and Display Formats.......................................................................... 8

2 Parameters in Configuration Mode ....................................................................................... 9

3 Modes and Example Displays ........................................................................................... 11

4 Voltage Display Ranges .................................................................................................. 12

5 Parameters in Analysis Mode............................................................................................ 13

6 Console Mode Commands............................................................................................... 19

7 Load Cell Header Pinout ................................................................................................. 21

8 Terminal Block Pinout..................................................................................................... 22

9 ADS1x31REF Bill of Materials .......................................................................................... 23

ADS1131REF and ADS1231REF SBAU175A–July 2010–Revised August 2011

Submit Documentation Feedback

www.ti.com

Getting Started

1 Getting Started

A diagram of the ADS1x31REF is shown in Figure 1.

Figure 1. ADS1x31REF Controls and Connectors

1.1 Operating Modes

The ADS1x31REF operates in one of three modes:

• Scale mode: When the mode select switch is in Scale position, the ADS1x31REF acts as a basic

weigh scale. The scale has tare, range, and calibrate functions, and can display metric (SI) units. Other

parameters can be configured in configuration screens. Scale mode is described in detail in Section 2.

• Analysis mode: When the mode select switch is in Analysis position, codes are taken directly from the

installed ADS device and various measurements are made upon them. Several measurements are

available, including raw display, voltage, RMS noise, and peak-to-peak measurements. The ADS1131

or ADS1231 can also be configured directly from this mode. Analysis mode is described in detail in

Section 3.

• Configuration mode: Parameters governing the operation of the ADS1x31REF can be viewed and

altered in this mode. Scale and Analysis modes have different options in configuration mode:

configuration for Scale mode is described in Section 2.4, and configuration for Analysis mode is

described in Section 3.4.

SBAU175A–July 2010–Revised August 2011 ADS1131REF and ADS1231REF

Submit Documentation Feedback

Part #	897-43-004-90-000000
Description	CONN RECEPT USB TYPE B PCB
Category	SOCKET
Availability	Out of Stock
Qty	0

897-43-004-90-000000

Related Items

Technical Document