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ADS1298RECGFE-PDK: Reading respiration data

Part Number: ADS1298RECGFE-PDK
Other Parts Discussed in Thread: ADS1298R

howdy!

I have been using an ADS1298R development board without the MMB0 DSP processor, Talking directly to the chip via SPI. I have gotten successful results with ECG waveforms simulated using a  fluke prosim8. I wanted to test wheater I can read the respiration data from the simulator (configured to output respiration waveforms) through the inbuilt dedicated hardware of the ADS1298R. I was successful in obtaining the test waveform generated by the MSP430 on board. I have attached an image of the waveform below. I then configured it to measure the waveform from the fluke however, all I observed is noise (image below). Here are my register configurations. Have I done something wrong? or is there a different config? 

Register configs : 

CONFIG4: Configuration Register 4

Bit

Field

Description

7:5

RESP_FREQ[2:0]

001 = 32 kHz modulation clock

4

RESERVED

Always write 0h

3

SINGLE_SHOT

0 = Continuous conversion mode

2

WCT_TO_RLD

0 = WCT to RLD connection off

1

PD_LOFF_COMP

0 = Lead-off comparators disabled

0

RESERVED

Always write 0h

 

write_register(CONFIG4, 0x20u);

 

CH1SET: Individual Channel Settings

 

Bit

Field

Description

7

PDn

0 = Normal operation

6:4

GAINn[2:0]

011 = PGA 3

3

RESERVED

Always write 0h

2:0

MUXn[2:0]

000 = Normal electrode input

 

write_register(CH1SET, 0x30u);

write_register(CH2SET, 0x30u);

 

RESP: Respiration Control Register

Bit

Field

Description

7

RESP_DEMOD_EN1

1 = RESP demodulation circuitry turned on

6

RESP_MOD_EN1

1 = RESP modulation circuitry turned on

5

RESERVED

Always write 1h

4:2

RESP_PH[2:0]

100 = 112.5° phase

1:0

RESP_CTRL[1:0]

10 = Internal respiration with internal signals

write_register(RESP, 0xF2u);

 

The above plot is with the test signal generated by the onboard msp450. below is the plot by the signal generated by the prosim 8 by FLUKE. Note that JP34,35 were switched to electrode inputs.

  • Hi Ravindu,

    Thank you for your post and welcome to our forum.

    The first image you shared with the on-board respiration waveform from the MSP430 did not come through. Can you please reattach?

    To use external respiration inputs (i.e. from your Fluke ProSim8), you must change the jumper settings on JP34 and JP35 to the [2-3] position. Also, double-check that the simulator is properly configured and enabled for respiration output. You will likely have to select which lead respiration is measured on (i.e. LA-RA for Lead I respiration). Try adjusting the respiration impedance setting to at least 1 ohm peak-to-peak to make it more apparent.

    Best regards,

  • Thanks, I will look up on the one-ohm impedance. Here is the on-board respiration waveform.