urm 70 is about right for the analog in.
3.3/1023 * 68 = 219mV
3.3/1023 * 70 = 225mV
3.3/1023 * 72 = 232mV
3.3/1023 * 240 = 774mV
Slight margin of error...
The value you are reading on the input is not voltage, it's a digital representation of the vRef.
0=0v, 1023=3.3V
The last example, if you saw 240 in the .Read() you would actually have a voltage of 774mV
Crispin,
Thank you, both for your original Distance class and for explaining how I was misinterpreting what I was seeing on the analog input pin. I now realize that I am seeing the digital representation of the vRef when reading the analog input pin rather than the actual voltage I was seeing on the digital multimeter. The computation which you use I now realize is based on the fact that the Netduino is using a 10 bit ADC.
I'm guessing the fluctuations I am seeing in my readings are due to electrical noise - I soldered a female header onto the Maxbotix but the connections themselves are just jumper wires pushed into headers.
Again, thanks for your help.
Paul