3 blinks:
The converter is ready, both channels are flat1.
2 blinks:
The converter is ready, one channel is flat1 and one exhibits a valid PWM signal. 1 blink:
The converter is ready, both channels exhibit valid PWM signal.
1 Flat can mean that something is wrong with the connection, but also that the control is just all the way up or down. The converter will create the correct ESC signal for the latter two cases.