Changes Required for Arduino IDE

[github-ec]

Thanks for the great work provided with your DAC-cosine program! Although the functionality has some limitations it is still fascinating to have ability to create cosine signals without CPU load!

Just a hint for users of the Arduino IDE. It requires only a few changes to get dac-cosine.c compiled:

• Change "void app_main()" to "void setup()"
• Add "void loop() {}" at the end of the program

as the IDE expects the declaration of setup() and loop() ...