In this project I will present an EEG/ECG data logger with capacitive electrodes. The module will have 6 single ended and 2 differential electrode inputs.
An ADS1299 analog front-end chip will convert the analog signals to digital data. This IC implements the necessary protections from the input( ESD etc.), it contains amplifiers and anti-aliasing filters, so no additional components are needed for usage.
The digital data is fed to the RFM79 trans-receiver module via PIC18F14K22 microcontroller. On the receiver side I used the same RFM79 module, which sends the data to a PIC24FJ64GB002 microcontroller in which the 50Hz noise and various low-pass filters will be implemented. The microcontroller sends the conditioned data to the PC through custom USB HID interface.
In the PC a C# program will graph the data in real time, and it will also save the data for later use.
Data Converters / Analog to Digital Converter ICs (ADCs)