PX4 PWM Generate

I am trying to generate a PWM signal to control Cree led which reqires a PWM signal (1100us to 1900us) of voltage range 3V to 48V.

The link for Cree LED specifcations and a sample code is as follows.

I am trying to generate this signal using a PX4 board and using main channels for the same. But after generating the PWM signal the LED does not glow as the voltage on the pwm pin of px4 is measured to be 2.8v. The PX4 is being powered by USB cabel.

Can you help me with generating the PWM signal of 3 volts or more.