netduino GPIO speed test
I wanted to figure out the kind of throughput achievable through bit-banging on GPIO pins on the netduino.
The basic idea for the test was to flip a bit as fast as possible on a single output pin connected to an LED with a ~215 ohm resistor, measuring the frequency of the changes on an oscilloscope.
The little code snippet below is about as simple as it gets for this test.
public class Program
public static void Main()
var d0 = new OutputPort(Pins.GPIO_PIN_D0, false);
The result turned out to be surprisingly low, clocking in @ 8.4 kHz!
8.4 kHz = 8400 bits / sec = 1050 bytes / sec.
To put things into perspective, according to the list of device bit rates on Wikipedia, 8.4 kHz lands us right around modem technology circa 1989.
Ah! To feel young again ;-)