DS2781EVKIT+ - Maxim Integrated

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FEATURES

 Demonstrates the capabilities of the DS2781

Standalone Fuel Gauge, including:

 Estimation of available capacity for Li+

cells

 Voltage measurement

 Current measurement

 Current accumulation

 Temperature measurement

 Information storage

 Identification

 Interfaces to the USB port of a PC running

Windows XP or older operating system

INDEX

Evaluation Kit Contents

Equipment Needed

Introduction

Setup and Installation

Board Connections

Software Installation

Selecting the COM Port

Program Menus

Menu Windows

Status Register

Program Tabs

Real Time Tab

Parameters Tab

Memory Tab

Log Data Tab

EVALUATION KIT CONTENTS

1 pc. Evaluation Board

1 pc. DS9123O USB Port Adapter

1 pc. RJ-11 Cable

EQUIPMENT NEEDED

1. A PC running Windows XP or older operating

system and an available serial port.

2. Cables with mini-grabber style clips or the

ability to solder directly to connection pads.

3. A Lithium-Ion battery and a power supply

and/or load circuit.

INTRODUCTION

The DS2781 evaluation kit (EV kit) makes performance evaluation, software development, and

prototyping with the DS2781 Standalone Fuel Gauge easy. The evaluation board interfaces to a PC

through a DS9123O USB Port Adapter and RJ-11 cable connection.

The DS2781 EV kit evaluation software gives the user complete control of all functions of the DS2781.

Separate control tabs allow the user access to all EEPROM and RAM memory locations, all control

registers, and real-time updates of all monitored parameters. The software also incorporates a data-

logging feature to monitor a cell over time.

DS2781EVKIT+

Standalone Fuel Gauge IC Evaluation Kit

19-4852; Rev 9/09

www.maxim-ic.com

PD020805

DS2781EVKIT+ TSSOP

Windows XP is a registered trademark of Microsoft Corp.

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The evaluation board circuit is designed to provide the DS2781 with accurate parameter measurements.

Kit demonstration boards will vary as they are improved upon over time.

SETUP AND INSTALLATION

BOARD CONNECTIONS

Connections to the TSSOP demonstration board are best made either by soldering directly to the pads or

by using cables with mini-grabber clips. Communication to the TSSOP board can be accomplished either

through the RJ-11 jack by connecting the provided standard six conductor RJ-11 cord or by wiring

directly to the DQ and P- pads. In the latter case, the size of the board can be reduced by snapping off the

RJ-11 jack along the break line, see Figure 1. To utilize the demonstration software, the DQ and PAC-

lines must be connected to the DS9123 communication brick using either of the two methods described.

Figure 1: Communication Connections

Figures 2a and 2b show the recommended circuits to simulate charging and discharging. The Lithium-Ion

cell is connected between the B+ and B- pads. The battery charger/power supply or circuit load is

connected between the B+ and P- pads. The evaluation software can be run in either configuration as long

as a cell is connected between the B+ and B- terminals providing a minimum of 2.5 volts to power the

DS2781. Leaving the PIO pin unconnected does not interfere with the operation of the demonstration

board. Refer to the datasheet for the operation of this pin.

Figure 2a: Charging Circui t Fi g 2b: Disch argi n g Ci rcui t

RJ-11

Break Line

P-

B-

PIO

B+

P -

BATTERY

DS2781EVKIT+ EVALUATION

BOARD

Power

Supply /

Battery

Charger

B-

PIO

B+

P -

BATTERY

DS2781EVKIT+ EVALUATION

BOARD

B-

PIO

LOAD

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SOFTWARE INSTALLATION

To install the DS2781 EV kit software, exit all programs currently running and download the latest

version at www.maxim-ic.com. Unzip the compressed folder and double click the SETUP.EXE icon to

begin the installation process. Follow the prompts to complete the installation. The DS2781 EV kit

software can be uninstalled in the Add/Remove Programs tool in the Control Panel. After the installation

is complete, open the DS2781K folder and run DS2781K.EXE or select DS2781K from the program

menu. A splash screen containing information about the evaluation kit appears as the program is being

loaded.

SELECTING THE COMMUNICATION PORT

The first time the software runs, the Select Preferences window appears. In this window, select either

serial port or USB communication and the port number; then hit OK. The DS2781 EV kit software saves

this port selection and automatically uses the selection each time the program starts. To change the port

later, click the Preferences option on the menu bar, select Port Settings, and then select the appropriate

port. To attempt to automatically locate the DS9123O, click the Poll Serial Ports button. Warning -

automatically polling for the DS9123O can disrupt other devices connected to your computer’s COM

ports.

PROGRAM MENUS

Several pull down menu options have been provided to simplify use of the DS2781 EV kit software for

the user. Their functions are individually detailed below.

FILE MENU

The File Menu allows the user to store and recall information to and from a file directly into the text

boxes on the Parameters Tab. These functions do not directly write or read the DS2781. It is still

necessary for the user to store or recall this information to or from the device by clicking on the Write &

Copy or Recall & Read buttons on the Parameters Tab.

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REGISTERS MENU

The Registers Menu gives immediate access to all four status and function registers of the DS2781.

Selecting any of the registers will open an individual control window giving the user a description of each

CONTROL REGISTER

The present state of all register bits are displayed immediately upon opening the register window. R/W

locations contain a selection field or command button to allow the user to determine their state. Pressing

the WRITE button will write the new value to the register and read the corresponding register inside the

DS2781 to verify the correct value was written. The Control Register is stored in EEPROM, so when the

WRITE command is issued, the value is written and copied to EEPROM without changing the values of

the remainder of the Parameter EEPROM block.

1 WIRE SPEED MENU

The 1 Wire Speed Menu allows the user to select the appropriate 1 Wire timing. The speed the device

uses is determined by the state of the OVD pin (pin 6).

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PREFERENCES MENU

The Preferences Menu allows the user to change COM port settings at any time. Edit Preferences opens

the Select Preferences window. See Selecting the communication port above.

HELP MENU

Selecting the About topic from the Help Menu will open a window containing information about the

current revision of this program and Dallas Semiconductor.

PROGRAM TABS

All functions of the program are divided under four tabs in the main program window. Left click on the

appropriate tab to move to the desired function page. Located on the Real Time tab is all of the

information measured and calculated by the DS2781. That data is divided between the Parametric Data

Tab and Fuel Gauging Tab. The Parameters Tab gives the user access to the entire Parameter EEPROM

memory block in terms of Application Units and Device Units. The Memory tab displays the contents of

every register and memory location inside the DS2781 and allows the user to alter the data. The Data

Log tab allows the user to store all real time information to a file and view the data in a graphical form.

REAL TIME TAB

The Real Time data is divided into two tabs: Parametric Data and Fuel Gauge Data. The Parametric Data

Tab contains all of the real time measurements taken by the DS2781. The Fuel Gauge Data contains all

of the values calculated by the DS2781.

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Parametric Data Tab

The Parametric Data Sub Tab displays the latest real-time measurements of cell voltage, temperature,

current and accumulated charge with both analog meter readouts and digital values. The sense resistor

value used to calculate the current reading is shown in the current section. Go to the sense resistor value

on the Parameters Tab to change this value

The present states of PIO pin is shown at the bottom left of the window. There is also a button to toggle

the state of the PIO pin.

Set Current Offset Bias Register

The user can bring up the Current Offset Bias Register window by left clicking the Current Offset Bias

button. This window allows the user to enter a value for the Current Offset Bias Register in mA. The

value entered here will be added to the Current Register during each current conversion. The bias value

will affect the Current Register reading, as well as the Accumulated Current Register.

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Set Accumulated Current Register

The user can bring up the Set Accumulated Current Register window by left clicking the Set ACR button.

This window allows the user to enter a value for the Accumulated Current Register in mAH.

Set Accumulation Bias Register

The user can bring up the Set Accumulation Bias Register window by left clicking the Set Acc Bias

button. This window allows the user to enter values for the Accumulation Bias Register in mA. The

value entered here will be added to the Accumulated Current Register during each current conversion.

The bias value will not affect the Current Register reading, but will be reflected in the Accumulated

Current Register.

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Fuel Gauge Data Tab

The Fuel Gauge Data Sub Tab displays the latest fuel gauge calculations. The Full, Active Empty, and

Standby Empty levels are calculated from the data input on the Parameters Tab. The Remaining Active

Absolute Capacity (RAAC) and the Remaining Stand-by Absolute Capacity (RSAC) are displayed in

terms of mAhrs. The Remaining Active Relative Capacity (RARC), Remaining Stand-by Relative

Capacity (RSRC) are displayed in terms of percent of capacity remaining. The Analog Meter on the left

displays the Remaining Active Absolute Capacity (RAAC).

The flags found in the Status Register are displayed on the right side of the window. When the Under

Voltage Flag or the Power-on-Reset Flag is set, a button will appear that will allow the user to clear those

bits.

Scalar Register

The user can bring up the Set Age Scalar window by left clicking the Update button in the Scalar area.

This window allows the user to read and write the Scalar value in terms of percent of the nominal

capacity.

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PARAMETERS TAB

The Parameters Tab gives the user access to the entire Parameter EEPROM memory block (block 1,

addresses 60h-7Fh) in terms of Application Units and Device Units. The Application Units Tab displays

the parameters in units like mA, mAhrs, and volts. The Device Units Tabs performs the calculations

needed to get the application units into the units that are stored in the device like μV, μVhrs, and ppm as

well as show the hexadecimal values that get written to the device.

Application Units Tab

The Application Units Sub Tab allows the user to read and write the Parameter EEPROM memory block.

To change any of this information, simply click on the desired text field and enter the new value.

Clicking on the Load Default Set Up button will enter example data into the information fields of the

Application Units Sub Tab. Once all data is in the desired format, click on the Write & Copy button to

copy it to the EEPROM of the DS2781.

This information can also be stored to a file and recalled later using the Load/Save Set Up buttons or the

Load/Save Parameters Set Up Menu Items. These functions do not directly write or read the DS2781. It

is still necessary for the user to store or recall this information to or from the device by issuing a Write &

Copy or Recall & Read buttons.

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Device Units Tab

The Device Units Sub Tab is read-only. It displays the actual hexadecimal values read from the DS2781

and displays the units that are stored in the device.

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MEMORY TAB

The Memory Tab gives the user access to all 32 bytes of SRAM and all 48 bytes of EEPROM inside the

DS2781. They are separated into four sub-tabs for convenience. Any value can be modified by clicking in

that address’ text box and typing a new value in hexadecimal format. The Write button will copy the

entire block of data to the corresponding location inside the DS2781 (Scratchpad RAM on the EEPROM

blocks). The Read button will update the entire block’s text boxes with data from the DS2781

(Scratchpad RAM on the EEPROM blocks). Sub-tabs displaying any EEPROM data will also have Copy

and Recall buttons to allow the user to transfer the data between Scratchpad and EEPROM memory

internal to the DS2781. The Permanently Lock Block 0/1 buttons will permanently store the data

currently located in that block’s EEPROM. Warning – this data can never be changed once locked. Verify

your data first by issuing a Recall and a Read.

The Net Address Sub Tab allows the user to perform a Search Net Address to find all of the 1-Wire

devices on the 1 Wire bus. All devices found on the bus will be listed in the Net Addresses field. To

communicate to any device on the bus, click on its address inside the Net Addresses field to select it. The

program will now use this Net Address for all operations until a different Net Address is chosen.

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LOG DATA TAB

The Log Data tab allows the user to see the DS2781’s real time measurements graphed over time. There

are separate sub-tabs for voltage, current, temperature, and accumulated charge. Each graph displays the

last 500 data points collected by the DS2781 EV kit software. The sampling interval can be adjusted from

as fast as possible to 15 minutes and can be adjusted from the Sampling Interval Menu at the bottom of

the window. The Clear Graphs button will clear all data from all four graphs, but does not reset the log to

file function. When the Fastest sampling interval is selected, the graphs will not be updated, only the data

logging is enabled.

The Log to File Sub Tab contains control information for storing all data to an ASCII file. The default

filename is c:\DS2781K_datalog.txt, but can be modified in the filename text field. The Log Data button

toggles data logging off and on. Data will be stored at the same interval selected for updating the graphs

in the tab-delimited format of

“Time<tab>Voltage<tab>Current<tab>AveCurrent<tab>Temperature<tab>ACR<tab>Full<tab>

AE<tab> SE<tab> RAAC<tab> RARC<tab> RSAC<tab> RSRC<tab> Status<tab> Scalar”

for easy import into a spreadsheet. The most recent 50 samples are displayed in the window for

observation. Warning - The Log Data function overwrites previous file information. Data previously

stored in the file will be lost.

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REVISION HISTORY

REVISION

DATE DESCRIPTION PAGES

CHANGED

9/09 Changed the part number from DS2781K to DS2781EVKIT+. All