ADS1299EEG-FE Daughter Card Hardware Introduction

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A 2.048MHz oscillator available for +3V and +1.8V DVDD is the FXO-HC735-2.048MHz and SiT8002AC-

34-18E-2.048, respectively. The EVM is shipped with the external oscillator enabled.

4.3 Reference

The ADS1299 has an on-chip internal reference circuit that provides reference voltages to the device.

Alternatively, the internal reference can be powered down and VREFP can be applied externally. This

configuration is achieved with the external reference generator (U3) and driver buffer. The EVM has the

footprints for the necessary circuitry, but the components are not installed at the factory.

The external reference voltage can be set to 4.096V. Measure TP3 to make sure the external reference is

correct. The setting for the external reference is described in Table 6.

Table 6. External Reference Jumper Options

Internal Reference External Reference

ADS1299 Reference

VREF = 4.5V VREFP = 4.096V

JP3 Not Installed Installed

The software uses the VREF value entered in the Global Registers control tab (refer to Section 5.2) to

calculate the input-referred voltage value for all the tests. The default value is 4.5V. If any other value is

used, the user must update this field in the Global Registers control tab.

4.4 Accessing ADS1299 Analog Signals

Some ADS1299 output signals are provided as test points for probing purposes through J5. Table 7 lists

the various test signals with the corresponding test points.

Table 7. Test Signals

Signal J5 Pin Number Signal

RESERVE 1 2 RESERVE

RESERVE 3 4 RESERVE

GPIO4 5 6 PWDNB

GPIO3 7 8 Daisy_in

AGND 9 10 RESERVE

4.5 Accessing ADS1299 Digital Signals

The ADS1299 digital signals (including SPI interface signals, some GPIO signals, and some of the control

signals) are available at connector J3. These signals are used to interface to the MMB0 board DSP. The

pin out for this connector is given in Table 8.

Table 8. Serial Interface Pin Out

Signal J3 Pin Number Signal

START/CS 1 2 CLKSEL

CLK 3 4 GND

NC 5 6 GPIO1

CS 7 8 RESETB

NC 9 10 GND

DIN 11 12 GPIO2

DOUT 13 14 NC/START

DRDYB 15 16 SCL

EXT_CLK 17 18 GND

NC 19 20 SDA

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ADS1299EEG-FE Daughter Card Hardware Introduction

4.6 Analog Inputs

The ADS1299EEG-FE is designed so that it can be used as a eight channel data acquisition board.

Arbitrary input signals can be fed to the ADS1299 by feeding the signal directly at connector J6. Figure 14

shows the input configurations that are available in the EVM.

Figure 14. Input Configurations Supported by the EEG-FE a) Differential Inputs b) Single ended inputs

4.6.1 Differential Inputs

To digitize eight differential inputs,

1. Set all jumpers to factory defaults as described in Section 2.5.

2. Remove jumpers from pin 7-36 of J6.

3. Provide the differential inputs on the even pins 8-36 of J6.

While used with differential inputs, care needs to be taken to ensure that the analog inputs are within the

input common mode range of the PGA. If the input differential signal is centered around 0V, the ADS1299

needs to be operated with a bipolar supply. Refer to Section 4.1 for details on setting the EVM to operate

with a bipolar supply.

4.6.2 Single Ended Inputs

For single ended inputs the measurement can be done with respect to the voltage applied to the SRB1 pin

of the ADS1299. To digitize eight single ended inputs,

1. Set all jumpers to factory defaults as described in

2. Remove jumpers from pin 7-36 of J6.

3. Short pin 5 and 6 of JP6. Set the SRB1 bit in the MISC1 register to route the SRB1 pin to the negative

input of the channels (refer to Section 8.3 for details). This will route BIAS_ELEC (mid supply) to the

negative inputs of the channels through the SRB1 pin.

4. Provide the Single ended inputs to pins 36, 32, 28, 24, 20, 16, 12, 8 of J6 for channels 1-8

respectively.

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Using the Software: ADS1299 Control Registers and GUI

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Apart from providing the option to feed inputs directly at the jumper (for general purpose data acquisition),

the ADS1299 EVM provides multiple configurations specific to the EEG application. These configurations

are explained in detail in Section 7.

5 Using the Software: ADS1299 Control Registers and GUI

Before starting to use the EVM software, there is one important feature that users should be aware of. The

software GUI contains a Save tab that allows all data from any combination of channels to be saved in a

given directory location with notes to describe the saved data. Figure 15 shows the Save tab options.

Figure 15. File Save Option Under 'Save' Tab

5.1 Overview and Features

This section provides a quick overview of the various features and functions of the ADS1299EEG-FE

software package.

There are four primary tabs across the left side of the GUI:

• About tab: Provides information about the EVM and software version revisions.

• ADC Register tab: Includes all of the control registers for the ADS1299, in a series of related sub-tabs:

– Channel Registers tab

– LOFF and BIAS tab

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Part #	142-0701-201
Description	SMA COAXIAL CONNECTOR
Category	CONNECTOR
Availability	In Stock
Qty	3

Manufacturer	Available	Qty
Military Spec	Freelance Stock: 2 Ships Immediately
Military Spec	Freelance Stock: 1 Ships Immediately

142-0701-201

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