The AD7705 is a two channel sigma delta converter which has differential inputs, a PGA and programmable data rates. It's perfect for slowly changing inputs such as pressure, temperature, heart rate etc.
This repo offers the class AD7705Comm which does all the low level
communications with the AD7705. The user just need to register a
callback handler which then returns the samples in realtime.
The class uses the DRDY of the AD7705 connected to Port 22 and waits for a falling edge on this port to read the data. This is done via interrupts / poll so that the ADC process sleeps until new data becomes available.
The design files (for EAGLE) are in the subdirectory "pcb".
To build:
cmake .
make
sudo make install
In the subdir example is a simple application which prints the ADC data to the screen.
cd example
sudo ./ad7705_printer
The online doc is here: http://berndporr.github.io/rpi_AD7705_daq/
class AD7705printSampleCallback : public AD7705callback {
virtual void hasSample(float v) {
// process your sample here
}
};
Instantiate the AD7705 class and the callback handler:
AD7705Comm ad7705comm;
AD7705printSampleCallback ad7705printSampleCallback;
ad7705comm.setCallback(&ad7705printSampleCallback);
Start the data acquisition:
ad7705comm.start();
once start has been called the data will be arriving.
Stop the data acquisition:
ad7705comm.stop();