This project need 10 inputs , but I want just two channels .
Is it possible?
I just want RA and LA two channels .
And the others are connected ground with TP8 on ADS1298.
How to redesign my project or my ADS1298 circuit ?
If you need only two channels why dont you use ADS1292? cheaper ..
Because I need other inputs but not ECG signal.
What sort of 'other inputs' do you need? Are you looking for digital I/O or are you looking to digitize analog signals of some sort? If analog, what is the nature of the signal (bandwidth, magnitude, etc)?
Yes, the other signal bandwidth :0Hz~150Hz , mv level.
I want to digitize analog signals .
So, could you reply my other question?
If I want two inputs :RA&LA, other signals are connected ground on ADS1298.
Will this action be OK ?
An ECG lead is a differential measurement. Lead I would a differential measurement across RA and LA. If you need to use single ended measurements on the other channels, you can do Lead I on channel 1 and the tie the (-) pins of channels 2 - 7 to ground and the (+) pin of those channels for single ended measurements for whatever else you need to measure.
Thanks for Tom's reply.
Second,I find out that the noise will be higher if just no RL signal.
Do the question have a solution?
You can use the remaining channels of the ADS1298 as a general purpose ADC to digitize analog signals - they do not have to be 'ECG' signals. The inputs to the ADS1298 are differential so your analog signal could be applied to the INx(+) pins, with the INx(-) grounded or tied to AVdd/2.
I know that ADS1298 is differential input,but RL is not a input.
It's a right leg drive circuit.
But I don't want the RL input .
Just RA and LA.
lead I is LA minus RA.
without RL electrode, the signal's noise is higher.
Your reply is that modify a single input .Right?
The RLD primary function is to set the operating point for the body. If you decide to not use the RLD, you will need to bias the inputs to the ADC using other means. This could be done by AC coupling the inputs and using weak pull up/down resistors to the ADC power supplies. Search around the forum and you will find others who are doing single lead ECG with no RLD electrode.
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