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ADS1292: ADS1292 RLD Register and Circuit Design

Part Number: ADS1292
Other Parts Discussed in Thread: ADS1291

Hi,

I am working on an EOG detection circuit using ADS1292. I could config ADS1292 and see the test signal(square wave), but the RLDOUT voltage and CH1/CH2 data output are strange under normal electrode input.

ads1292_Reg_Write(ADS1292_REG_RLDSENS, 0x20); RLDOUT is 1.65V with no AC components.

ads1292_Reg_Write(ADS1292_REG_RLDSENS, 0x2C); RLDOUT is average1.8V with 600mV sine wave(50Hz).

CH1/CH2 data output is usually near -1.7V or -2.42V; with small sine wave noise.

I am not sure whether the problem is due to my circuit design: RLD part and analog inputs(1N 1P 2N 2P); or it is due to the register configurations.

Unipolar supply: AVDD=3V; 2.42-V reference

ads1292_Reg_Write(ADS1292_REG_CONFIG1, 0x01);
ads1292_Reg_Write(ADS1292_REG_CONFIG2, 0xA0);
ads1292_Reg_Write(ADS1292_REG_LOFF, 0x10);
ads1292_Reg_Write(ADS1292_REG_CH1SET, 0x00);
ads1292_Reg_Write(ADS1292_REG_CH2SET, 0x00);
ads1292_Reg_Write(ADS1292_REG_RLDSENS, 0x23);
ads1292_Reg_Write(ADS1292_REG_LOFFSENS, 0x00);
ads1292_Reg_Write(ADS1292_REG_LOFFSTAT, 0x00);
ads1292_Reg_Write(ADS1292_REG_RESP1, 0x02);
ads1292_Reg_Write(ADS1292_REG_RESP2, 0x07);
ads1292_Reg_Write(ADS1292_REG_GPIO, 0x00);

Thank you for your support and advice

Best Regards,

Zhixia

  • Hi Zhixia,

    Thanks for your post and welcome to the forum!

    What is being applied to the inputs of channel 1/2?
    Are you using a known signal source or taking electrode readings?
    Do you get the correct output data for channel 1/2 using a known signal source?

    I do not see any issues with your schematic or register configurations.
  • Hi Alex,

    I was using 500mV vpp square wave as test input signal and set the gain=1.

    I soldered another board and using ADS1291 instead of ADS1292, and that works. I could see the external test signal or my ecg wave.
    Then I soldered another board with ADS1292, everything worked.

    The older ADS1292 board may have broke some part.

    Thank you for your support

    Best Regards,
    Zhixia
  • Hi Zhixia,

    Happy to hear that you found the issue!
    Best of luck!