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ADS1298: ADS1298 - electrodes impedance

Shlomi Yehezkia
Mastermind 6150 points
Part Number: ADS1298

Hi Team,

 

I need to know how to activate the impedance in ADS1298 chip .

According to (9.3.1.7.4 Lead-Off Detection) in datasheet , I should be able to detect electrode connection ( on/off ) using LOFF_STATP and LOFF_STATN  registers ,

I tried many values of registers 0x04,0x0f,0x10,0x11,0x12,0x13 and 0x17  and the result didn’t  change .

Status  word in return data is : 0xC0 0x0F 0xF0. Which mean the LOFF_STATP register not changes with value 1 for all channels .

 

The values of the registers which related to LEAD OFF are (what I think in order work ):

0x04 : 01111001

0x0F : 11111111

0x10 : 11111111

0x11 : 00000000

0x12 : default

0x13 : default

0x17 : 00000010

 

I would be thankful for any help .

Thanks,

Shlomi

 

  • 0
    TI__Guru 66186 points
    Hello Shlomi,

    Welcome to our forum and thank you for your post.

    The last two bits of the LOFF register (04h) must be 00 to use the DC lead-off detection method. The LOFF_STATP and LOFF_STATN bits are only updated by the comparators on each input pin when DC lead-off is used. Currently, you have configured the lead-off excitation current to be a square wave at at frequency of fDR / 4.

    Best regards,