Add example to readme

README.md

@@ -32,11 +32,28 @@ I wrote an example MIDI player that plays Beethoven's ninth symphony in hardware
 
 [driver-examples]: https://github.com/eldruin/driver-examples
 
-<!--
 ```rust
-TODO
+extern crate ad983x;
+extern crate linux_embedded_hal;
+
+use ad983x::{Ad983x, FrequencyRegister};
+use linux_embedded_hal::{Pin, Spidev};
+
+fn main() {
+    let spi = Spidev::open("/dev/spidev0.0").unwrap();
+    let chip_select = Pin::new(25);
+    let mut dds = Ad983x::new_ad9833(spi, chip_select);
+    dds.reset().unwrap(); // reset is necessary before operation
+    dds.set_frequency(FrequencyRegister::F0, 4724).unwrap();
+    dds.enable().unwrap();
+    // Given a 25 MHz clock, this now outputs a sine wave
+    // with a frequency of 440 Hz, which is a standard
+    // A4 tone.
+
+    // Get SPI device and CS pin back
+    let (_spi, _chip_select) = dds.destroy();
+}
 ```
--->
 
 ## Status