Here I`ve made a short video about how to control a SimonK ESC with an Arduino. (The SimonK firmware was already on the ESC when I bought it.) It can be controlled like a servo.

the code:

//This code is meant for controlling a SimonK ESC for a brushless motor.
//made by: Experimentaltechnik.com

#include <Servo.h>

Servo SimonKESC;
int potiPin = A2; //connect this pin with the middle pin of a potentiometer

//Connect the GND pins of the Arduino and the ESC.

void setup(){
SimonKESC.attach(3); //connect this PWM pin with the data cable of the ESC(usually white or yellow)
//motorESC.write(40); //if your ESC doesn`t have the SimonK firmware you can try this; remove the //signs
}

void loop(){
int poti = analogRead(potiPin);
poti = map(poti, 0, 1023, 0, 179);
SimonKESC.write(poti);
}