Texas Instruments ADS1299EEG-FE

To Next Page

User's Guide

SLAU443–May 2012

EEG Front-End Performance Demonstration Kit

This user's guide describes the characteristics, operation, and use of the ADS1299EEG-FE. This EVM is

an evaluation module for the ADS1299, an eight-channel, 24-bit, low-power; integrated analog front-end

(AFE) designed for electroencephalography (EEG) applications. The ADS1299ECG-FE is intended for

prototyping and evaluation. This user's guide includes a complete circuit description, schematic diagram,

and bill of materials.

The following related documents are available through the Texas Instruments web site at www.ti.com.

Device Literature Number

ADS1299 SBAS499

Contents

1 ADS1299EEG-FE Overview ............................................................................................... 4

1.1 Important Disclaimer Information ................................................................................ 4

1.2 Information about Cautions and Warnings ..................................................................... 4

2 Overview ..................................................................................................................... 5

2.1 Introduction ......................................................................................................... 5

2.2 Supported Features ................................................................................................ 5

2.3 Features Not Supported in Current Version .................................................................... 5

2.4 ADS1299EEG-FE Hardware ..................................................................................... 5

2.5 Factory Default Jumper Settings ................................................................................. 6

3 Software Installation ........................................................................................................ 7

3.1 Minimum Requirements ........................................................................................... 7

3.2 Installing the Software ............................................................................................. 7

3.3 Install the ADS1299 EVM Hardware Drivers ................................................................. 10

4 ADS1299EEG-FE Daughter Card Hardware Introduction ........................................................... 13

4.1 Power Supply ..................................................................................................... 14

4.2 Clock ............................................................................................................... 15

4.3 Reference .......................................................................................................... 16

4.4 Accessing ADS1299 Analog Signals .......................................................................... 16

4.5 Accessing ADS1299 Digital Signals ........................................................................... 16

4.6 Analog Inputs ..................................................................................................... 17

5 Using the Software: ADS1299 Control Registers and GUI .......................................................... 18

5.1 Overview and Features .......................................................................................... 18

5.2 Global Channel Registers ....................................................................................... 19

5.3 Channel Control Registers ...................................................................................... 19

5.4 GPIO and Other Registers ...................................................................................... 23

5.5 Lead-Off and BIAS Registers ................................................................................... 23

5.6 Register Map ...................................................................................................... 26

6 ADS1299EEG-FE Analysis Tools ....................................................................................... 27

6.1 Scope Tab ......................................................................................................... 27

6.2 Histogram Tool .................................................................................................... 28

6.3 FFT Tool ........................................................................................................... 29

7 EEG Specific Features .................................................................................................... 32

7.1 Reference Signal and Patient Bias Signal .................................................................... 32

SPI is a trademark of Motorola.

SLAU443–May 2012 EEG Front-End Performance Demonstration Kit

Submit Documentation Feedback

Main Page

Need help?

Do you have a question about the Texas Instruments ADS1299EEG-FE and is the answer not in the manual?

Overview

Function Description
Important Technical Specifications
Usage Features
Maintenance Features
Features Not Supported in Current Version

The ADS1299EEG-FE is an evaluation module designed for assessing the ADS1299, a low-power, low-noise, 24-bit, simultaneously sampling, eight-channel front-end specifically for EEG (Electroencephalography) applications. It is not intended as a reference design for EEG applications but rather to expedite evaluation and system development. The output of the ADS1299 provides a raw, unfiltered EEG signal.

Function Description:

The device is primarily used for electrical evaluation of the ADS1299 chip's features in laboratory and development environments. It allows users to provide arbitrary input signals directly to the ADS1299 via connector J6. The module supports various input configurations, including differential and single-ended inputs. For differential inputs, the device can digitize eight differential signals, with care taken to ensure analog inputs are within the PGA's input common mode range. For single-ended inputs, measurements are taken with respect to the voltage applied to the SRB1 pin of the ADS1299.

The ADS1299EEG-FE also includes features for internal test signals, temperature sensing, external calibration, and lead-off detection. Internal test signals, such as square waves, can be generated to verify the functionality of the signal chain (MUX, PGA, and ADC). An internal temperature sensor allows for temperature measurement, converting the ADC output voltage to a temperature value. External calibration and test signals can be provided to the ADS1299, either with channel inputs disconnected or connected.

Important Technical Specifications:

Channels: Eight integrated INAs (Instrumentation Amplifiers) and eight 24-bit high-resolution ADCs.
Noise: Low channel noise of 1µVpp for 65Hz bandwidth.
Power Consumption: Low power consumption (5mW/channel).
Data Rates: Supports data rates from 250SPS to 16kSPS.
Supply: 5V unipolar or bipolar analog supply, 1.8V to 3.6V digital supply.
Oscillator: On-chip oscillator.
Bias Amplifier: On-chip bias amplifier.
MUX: Versatile MUX to enable programmable reference and bias electrode.
Interface: SPI data interface.
Clock: On-chip oscillator generates a 2.048MHz clock (nominal), with an option to accept an external clock signal for higher accuracy. The external clock can be generated from either the onboard oscillator or an external source.
Reference Voltage: On-chip internal reference circuit provides reference voltages, with an option to power down the internal reference and apply VREFP externally (set to 4.096V).
Lead-Off Detection: Supports DC/AC lead-off detection with various current source options (6nA, 24nA, 6µA, 24µA) and frequencies (7.8Hz, 31.25Hz, or fDR/4).

Usage Features:

Configurable Supply: Can be configured for bipolar or unipolar supply operation.
Clock and Reference Configuration: Configurable for internal and external clock and reference via jumper settings.
Input Coupling: Configurable for DC-coupled inputs.
Bias Electrode Drive: External bias electrode drive is supported.
Common Reference: Option to provide a common reference to all channels' negative terminals.
Reference Electrode Selection: Option to select any electrode as the reference electrode.
Bias Electrode Selection: Option to choose any electrode as the bias electrode.
Shield Drive Amplifier: External shield drive amplifier is included.
Software GUI: The accompanying software provides a graphical user interface (GUI) for manipulating ADS1299 configuration and lead-off registers, including global channel registers (Configuration Register 1, 2, 3, and Lead-Off Control Register) and channel control registers.
Analysis Tools: Software includes analysis tools such as a virtual oscilloscope (Scope tab), histogram (Histogram tab), and FFT (FFT tab) for analyzing captured data in time or frequency domains.
Data Export: Allows for data export for post-processing of raw EEG data.
Register Map: A debug feature allows users to view the state of all internal registers.
Programmable Reference and Bias Electrodes: The internal multiplexer allows any electrode to be chosen as the bias or reference electrode.
Patient Biasing: Two options for biasing the patient: using the onboard BIAS_ELEC signal or the BIAS_DRV signal generated by the ADS1299 chip, with the latter offering improved common mode rejection through a feedback loop.

Maintenance Features:

Software Installation: Requires installation of specific software on a PC meeting minimum requirements (Pentium III®/Celeron® 866MHz, 256MB RAM, USB 1.1, 200MB free disk space, Microsoft® Windows® XP SP2, 1280x960 display). Users are cautioned not to connect hardware before software installation.
Hardware Driver Installation: USB drivers for the MMB0 and USBStyx are installed following specific steps after applying power and connecting the MMB0 to the PC.
Firmware Download: Upon initial software launch, firmware is downloaded to the processor on the data capture card (MMB0), causing the USB to re-enumerate.
ESD Handling: Users are advised to observe proper ESD handling procedures when unpacking and handling the EVM due to the susceptibility of components to electrostatic discharge. This includes using a grounded wrist strap, bootstraps, or mats at an approved ESD workstation, and wearing an electrostatic smock and safety glasses.
Power Supply Recommendations: For best performance and to minimize 50Hz/60Hz noise pickup, it is recommended to power the ADS1299EEG-FE with a battery source (e.g., a +6V battery pack with four 1.5V batteries in series) rather than a wall-powered source.
Troubleshooting: The manual provides guidance for troubleshooting, such as power cycling and restarting the program if an error message occurs during initial software launch or if the device is plugged into a different USB port.
Updates: Users are recommended to check the TI website for the latest software versions.