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User

'

s Guide

SBAU120B

November 2005

Revised July 2011

ADS1232REF User

'

s Guide

The ADS1232REF is a reference design for the

ADS1232

24-bit, delta-sigma analog-to-digital converter

(ADC). It contains all the circuitry and user interface elements needed for a weigh-scale digitizer, and is
meant as an example of good design for a basic weigh-scale system. The ADS1232REF is also suitable
for general evaluation of the ADS1232 device. Additionally, performance results obtained with the
ADS1232REF are applicable to the

ADS1234

, a device with identical performance.

The ADS1232REF hardware has the following features:

ADS1232 ADC

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 1.1.0 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.

1

SBAU120B

November 2005

Revised July 2011

ADS1232REF User

'

s Guide

Submit Documentation Feedback

Copyright

©

2005

2011, Texas Instruments Incorporated

Summary of Contents for ADS1232REF

Page 1: ...emote control Designed for very low power consumption Battery 9V or wall power Version 1 1 0 of the firmware includes the following features Weigh scale mode with two point calibration Complete config...

Page 2: ...REF Hardware Block Diagram 20 9 ADS1232REF PCB Top Side 25 10 ADS1232REF PCB Bottom Side 25 11 ADS1232REF Schematic ADC 26 12 ADS1232REF Schematic MCU 27 13 ADS1232REF Schematic USB 28 List of Tables...

Page 3: ...odes are taken directly from the ADS1232 device and various measurements are made upon them Several measurements are available including raw display voltage RMS noise and peak to peak measurements The...

Page 4: ...be set to JTAG 1 3 Powering the Board To apply power to the ADS1232REF connect a 9V battery or plug in a 6V to 9V ac wall adapter AC adapters must be tip positive sleeve negative When an ac adapter is...

Page 5: ...a 4 wire load cell to the header In this configuration the load cell is excited by the 5V power supply and the ADC reference is taken from the power supply Figure 4 4 Wire Load Cell to Header For thi...

Page 6: ...e product data sheet are taken with the inputs shorted to 2 5V These noise measurements can be replicated on the ADS1232REF with no external hardware To set up these measurements on the ADS1232REF per...

Page 7: ...ected disconnect them see Figure 1 3 Obtain a weight of known mass 4 If the mass of the weight is not equal to the configured calibration mass adjust the calibration mass as described above 5 Move the...

Page 8: ...llowed by st followed by pounds displayed to two decimal places 2 1 1 Calculation of Mass Mass is calculated from ADC code using the formula w m c wzs wt where w mass c the ADC code wt tare weight m w...

Page 9: ...ns simultaneously The four buttons then assume the functions shown in the CONFIG box To exit Configuration mode press the PARM buttons simultaneously again This function does not cause parameters to b...

Page 10: ...sted with the PARM buttons The VALUE buttons are used to select the digit The unit is adjusted in the same manner and flashes when selected When the unit is changed the value changes to the equivalent...

Page 11: ...able units Not all units are available in all modes DISP When this switch is pressed the display shows the current measurement mode and unit While DISP is still pressed pressing UNIT cycles through th...

Page 12: ...calculation is selected in Configuration mode 50 codes are used in laboratory characterization so this value is the default Peak to peak noise In this mode a number of codes are collected and the abso...

Page 13: ...ns The choices available are 2 4 8 10 16 32 50 64 100 and 128 The default setting is 50 Voltage reference To convert voltages to codes the ADS1232REF requires the voltage reference level Since this le...

Page 14: ...talls it and quits You must run the installer again to complete the installation If the Virtual COM Port driver is already installed the installer offers to uninstall it Do not uninstall it cancel thi...

Page 15: ...ADS1232REF connected The program uses the first ADS1232REF it finds Figure 6 ADS1232REF Software Display Although this procedure is conceptually simple it may not go as smoothly as expected The follo...

Page 16: ...led and dimmed while Analysis occurs 4 6 1 Averaging The PC software can process data collected from the board using a sliding window averager The controls for the averager are found in the Averager b...

Page 17: ...normally taken from the 5V power supply If a different reference voltage level is used the value of Vref should be changed to reflect the different level so that voltage calculations are performed co...

Page 18: ...Vref control it is therefore important that this value be correct 5 Serial Console The ADS1232REF provides a console mode that can be used with any Windows terminal emulation program such as Hyperterm...

Page 19: ...gain to 64 P3 sets gain to 128 P with no argument prints the current gain setting 5 2 2 R Set Data Rate This command sets the speed of the ADS1232 according to these parameters RF sets rate to fast RS...

Page 20: ...es the current channel setting 5 2 8 Q Query Parameters Q causes the ADS1232REF to issue a coded string summarizing the current settings The format of the string is P 0 3 R F S OIC 0 1 T followed by a...

Page 21: ...additional RF rejection 6 4 2 Load Cell Header The load cell header J6 provides a convenient terminal for load cells having a properly fitted header connector It provides excitation and sense connecti...

Page 22: ...ade from R25 and R26 dividing the power supply by 2 This voltage divider electrically resembles an ideal bridge sensor 6 5 USB Interface The USB interface can be used for firmware download or data com...

Page 23: ...sistor Panasonic ERJ 3GEYJ152V R4 R10 R16 10K 1 10W 5 Chip Resistor Panasonic ERJ 3GEYJ103V R25 R26 20K 1 16W 1 Chip Resistor Panasonic ERJ 3EKF2002V R18 R27 47K 1 10W 5 Chip Resistor Panasonic ERJ 3G...

Page 24: ...J8 1 X 2 Header Samtec TSW 102 07 G S J4 J5 3 5mm PCB Terminal Block On Shore Technology ED555 4DS 4 position N A ADS1232 REF PCB Texas Instruments 6474748 D1 30V 200mA Schottky Diode Fairchild Semico...

Page 25: ...PCB Layout Figure 9 ADS1232REF PCB Top Side Figure 10 ADS1232REF PCB Bottom Side 25 SBAU120B November 2005 Revised July 2011 Schematic and Layout Submit Documentation Feedback Copyright 2005 2011 Texa...

Page 26: ...DWN 22 SCLK 23 DRDY DOUT 24 U6 ADS1232IPW TP15 GND J5 OST_ED555 4DS J4 OST_ED555 4DS 1 2 3 4 5 6 J6 HEADER 6 5VA EXC EXCSNS SIG SIG EXCSNS EXC NO 1 GND 3 COM 2 V 5 IN 4 U7 TS5A3166DCK 5VA EXC C4 100uF...

Page 27: ...C2 60 DVSS2 61 U5 M SP430F449IPZ R19 221K R20 221K R21 221K C13 0 01uF C14 0 01uF C15 0 01uF 3 3VD R22 200K SW2 RANGE SW3 TARE SW4 CAL SW5 CONFIG 3 3VD R7 10K R8 10K R9 10K R10 10K R12 100 R13 100 C25...

Page 28: ...USB RESET TP2 3 3V_USB RX TX RTS DTR C3 4 7uF R17 20 FB SENSE 1 RESET 2 EN 3 GND 4 IN 5 IN 6 OUT 7 OUT 8 U3 TPS77133DGK 2 4 5 3 U10 SN74LVC1G04DBV 2 4 5 3 U11 SN74LVC1G04DBV USB3 3V USB3 3V USB3 3V US...

Page 29: ...guration section 9 Updated Table 2 9 Revised Section 2 4 1 10 Corrected button nomenclature in Section 3 11 Revised button nomenclature in Section 3 4 13 Corrected button nomenclature errors in Sectio...

Page 30: ...orized for use in safety critical applications such as life support where a failure of the TI product would reasonably be expected to cause severe personal injury or death unless officers of the parti...

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