I'm glad that you got the example to work. I'm afraid I don't have the exact device you mentioned to test with, but I can give you an overview of the general direction you would go about implementing the code for communicating with this device.
Firstly, as the datasheet explains starting on page 49 of the datasheet, you need to initiate the conversion on the device by sending a command to the device, then wait an appropriate amount of time and then issue a read command for the DATA register. So for example, in Arduino you would do something like this (note this code isn't being provided as 100%, you will likely need to add some more details, but hopefully you get the point for how to do the SPI interfacing):
#define ADCMODE 0x01
#define CONTINUOUS_READ 0x8000
#define DATA 0x04
#define READ (0 << 6)
#define WRITE (1 << 6)
void setup(){
SPI.begin();
//setup the device for continuous reading
// take the SS pin low to select the chip:
digitalWrite(slaveSelectPin, LOW);
//send a write command to set the ADC into continuous read mode
//need to write this mode to the ADCMODE register
SPI.transfer(WRITE | ADCMODE);
SPI.transfer(CONTINUOUS_READ);
// take the SS pin high to de-select the chip:
digitalWrite(slaveSelectPin, HIGH);
}
void loop(){
//select the device for reading
digitalWrite(slaveSelectPin, LOW);
//transfer the 4 bytes
uint8_t buffer[4] = {0};
//read from the DATA register
SPI.transfer(READ | DATA);
//get the data into the buffer
SPI.transfer(buffer,4);
//now need to combine the bytes together - NOTE this is for MSB
unsigned long int value = buffer[0] << 24 | buffer[1] << 16 | buffer[2] << 8 | buffer[3];
digitalWrite(slaveSelectPin, HIGH);
//need to determine what to set RATE to to get sufficient readings - see page 18 of datasheet
delay(RATE);
}
The datasheet I am referencing can be found here : http://www.analog.com/media/en/technical-documentation/data-sheets/AD7177-2.pdf
Once you get this code working in the Arduino IDE directly, then you can modify the code so it works with the Arduino driver in Mathematica.
