SLAU443 Datasheet, PDF (23/68 Pages) Texas Instruments – EEG Front-End Performance Demonstration Kit

www.ti.com
Using the Software: ADS1299 Control Registers and GUI
5.3.3 Normal Electrode Input
The Normal electrode input on the MUX routes the inputs (VINP and VINN) differentially to the internal
PGA, as Figure 17 illustrates. An exception is if the SRB1 bit is set high. If channel is in Normal electrode
mode and SRB1 bit is set high the signal on SRB1 pin is routed to negative inputs of all channels instead
of VINN inputs.
5.3.4 MV_DD Input and the Scope Tab
The MV_DD input option allows the measurement of the supply voltage V_S = (AV_DD + AV_SS)/2 for channels 1,
2, 5, 6, 7, and 8; however, the supply voltage for channel 3 and 4 will be DV_DD/4. As an example, in
bipolar supply mode, AV_DD = 3.0V and AV_SS = –2.5V. Therefore, with the PGA gain = 1, the output voltage
measured by the ADC will be approximately 0.25V.
5.3.5 Bias Measurement
This measurement takes the voltage at the BIASIN pin and measures it on the PGA with respect to
(AVDD + AVSS)/2 or BIASREF. This option can be used to give a calibration/test signal to ADS1299
device without connecting the calibration/test signal to the electrodes. The positive signal can be applied
to BIASIN pin and the negative input can be applied to the BIASREF pin. More details on this can be
found in Section 7.3.
5.3.6 Bias Positive Electrode Drive and Bias Negative Electrode
This option can be used to have a selectable bias electrode. This option routes the signal on BIASIN pin
to any of positive or negative pins of the channel inputs.
5.4 GPIO and Other Registers
The GPIO and Other Registers tab, located under the Analysis tab, includes controls for GPIO1 through
GPIO4, SRB1 control, pulse mode control and lead off comparators power down. The GPIO registers
control four general-purpose I/O pins. Figure 23 illustrates the GPIO Control Register GUI panel.
Figure 23. GPIO Control Register GUI Panel
5.5 Lead-Off and BIAS Registers
The Lead-Off Detection and Current Control Registers and the Bias Derivation Control Registers are
located under the ADC Register→LOFF and BIAS tab.
SLAU443 – May 2012
Submit Documentation Feedback
EEG Front-End Performance Demonstration Kit
23
Copyright © 2012, Texas Instruments Incorporated