• State TI Thinks Resolved
  • Replies 3 replies
  • Answers 2 answers
  • Subscribers 46 subscribers
  • Views 33 views
  • Users 0 members are here
Support feedback
Options
Options
Similar topics

ADS1299: Is 12 Lead ECG possible?

Vedashree Varra
Intellectual 320 points
Part Number: ADS1299
Other Parts Discussed in Thread: ADS1298R

Tool/software:

Hi,

I am using Cyton from Open BCI which includes ADS1299 with 8 channels. To acquire 12 Lead ECG they suggested another board called daisy module with another ADS1299. So, basically two AFEs are in use.

I figured the connection of Lead-1,2,3. Now as for the chest leads V1-V6, there is no WCT pin available in ADS1299 as in ADS1298R. So how should I give reference to V1-V6 leads in my case?

Is it possible to actually acquire 12 lead ECG with ADS1299?

Please guide me through this.

Thank you.

  • 0
    TI__Guru 59126 points

    Hello - The ADS1299 does not have an integrated WCT generation circuit. To measure the chest leads in analog, you would have to design a discrete summing amplifier circuit to average the RA, LA, and LL electrode potentials.

    Otherwise, the best solution may be to derive all primary leads, WCT voltage, and chest leads in software. Theoretically, you could do this by measuring each electrode individually with respect to GND and then computing the leads in post processing. 

    Regards,

    Ryan

  • 0 in reply to Ryan Andrews
    Intellectual 320 points

    Thank you Ryan for suggesting possible solutions.

    If the calculation of WCT is done in software, you mentioned the primary leads to be measured individually with respect to GND. What is "GND" here?

    Is it BIASOUT or AVSS or any other connection? 

    In the datasheet of ADS1299, it is given as below,

    So, I must route BIASIN to each of the primary leads and measure the signal with respect to BIASREF?

    Please clarify.

    Thank you.

  • 0 in reply to Vedashree Varra
    TI__Guru 59126 points

    Hello Vedashree,

    You would not use the BIASIN for this purpose. When a channel is configured to measure BIASIN, the result will be (BIASIN - BIASREF) x Gain. The channel input pins are disconnected from the PGA in this setting.

    For the single-ended inputs, the negative input can any constant reference, such as GND, or mid-supply (i.e. BIASOUT). The common-mode will cancel when you calculate the differential voltage between two inputs. 

    Regards,

    Ryan