RoboteQ AX2550/2850 user manual Cabling to R/C Receiver with Partial Opto-Isolation

Cabling to R/C Receiver with Partial Opto-Isolation

The opto isolators must be powered with a 5V supply for their built-in amplifiers to work. This power is normally supplied from the R/C radio’s battery as detailed in the diagram on Figure 45.

Note that if full optical isolation is required, it is not possible to connect the third R/C channel to the radio. Since the 3rd channel is not optoisolated, connecting it to the radio will cause the radio’s ground to be electrically tied to the controller ground, thus breaking the optical barrier.

This wiring, with a separate R/C battery, is the preferred method for connecting the R/C radio.

Radio

Battery

R/C Radio

	14			Controller
				Power
R/C Radio Power		7	Opto-
			Isolators

R/C Channel 1	3
R/C Channel 2	4	MCU
	8
R/C Radio Ground	6
	5-13	Controller
		Ground

FIGURE 45. Fully opto-isolated connection to R/C radio

Cabling to R/C Receiver with Partial Opto-Isolation

This wiring option should be considered only when the Accessory R/C channel (Channel 3) is required. Since Channel 3 is directly connected to the AX2500/2850’s microcontroller without opto coupler, it is necessary to connect the radio and controller grounds together to create a common ground reference for the signal. Since the Channel 3 connector has a ground wire, this connection will occur when the connector is plugged in the radio. The red loop wire must be cut to enable that mode. The radio will be powered from its own sepa- rate battery using this wiring scheme.

By joining the grounds and having the R/C signal connected directly from the radio to the controller, the full electrical barrier is lost. However, since the radio’s +5V and controller

AX2500/2850 Motor Controller User’s Manual 75