Mega 2560 + Ethernet Shield: Pin 9 not outputting PWM

Community General Discussion
1

I'm trying to use 4 PWM outputs from the ethernet shield. I want them to be right next to each other for easy modification

Mega's documentation (http://arduino.cc/en/Hacking/PinMapping2560) states that pin 6,7,8,9 are PWM pins, and from what I understand these pins are not used by the Ethernet Shield by default. (according to Arduino Playground - Shield Pin Usage)

However when I run my program (50% duty cycle), only pins 6,7,8 gives me the PWM signals.

I'm using a simple loop to initialize the PWMs using #defined values.

	void init()
	{	
		//loop through the pins, set them as output and zero them
		for (int i = 0; i < NUM_MOTORS; i++) {
			pinMode(MOTOR_PIN_LIST[i], OUTPUT);
			analogWrite(MOTOR_PIN_LIST[i], 0);

			pinMode(MOTOR_PIN_DIR_LIST[i], OUTPUT);
			digitalWrite(MOTOR_PIN_DIR_LIST[i], 0);
		}

		pinMode(PIN_MOTOR_DISABLE, OUTPUT);
		motor_setAll(50, 50, 50, 50); //xxx
	}

where the constant array and defines are:

const int NUM_MOTORS = 4;

//Motor pins
typedef enum motor_pin_t {
	//PWM pins
	PIN_MOTOR_VERT = 6,
	PIN_MOTOR_LAT = 7,
	PIN_MOTOR_LEFT = 8,
	PIN_MOTOR_RIGHT = 9,
	
	//Motor Shutdown Pins
	PIN_MOTOR_DISABLE = 18
};

const int MOTOR_PIN_LIST[NUM_MOTORS] = {PIN_MOTOR_VERT, PIN_MOTOR_LAT, PIN_MOTOR_LEFT, PIN_MOTOR_RIGHT};

Any ideas? Thanks for your help in advance.

2

My guess would be an error is one of the parts of your sketch you didn't show.

3

And you're right.
One of my sanity checks are off by one.

talk about insane sanity checks.

Thanks.