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R/C Operation
108 AX1500 Motor Controller User’s Manual Version 1.9b. June 1, 2007
Similarly, if the pulse train is lost while the motors were enabled, the controller will wait a
short preset amount of time before it disables the motors. If the pulses reappear during
that time, the controller continues without any breaks. If the communication is confirmed
to be lost, the “no ctrl” message is displayed again.
Note: the Accessory Outputs C will be turned Off when radio is lost.
Important Notice about PCM Radios
PCM radios have their own watchdog circuitry and will output a signal (normally a
“safe condition” value) when radio communication is lost. This signal will be inter-
preted by the AX1500 as a valid command and the controller will remain active. To
benefit from the AX1500’s radio detection function, you will need to disable the PCM
radio watchdog.
R/C Transmitter/Receiver Quality Considerations
As discussed earlier in this chapter, the AX1500 will capture the R/C’s command pulses
with great accuracy. It will therefore be able to take advantage of the more precise joy-
sticks and timings that can be found in higher quality R/C radio, if such added precision is
desired in the application.
Another important consideration is the R/C receiver’s ability to operate in an electrically
noisy environment: the AX1500 switches high current at very high frequencies. Such tran-
sients along long battery and motor wires will generate radio frequency noise that may
interfere with the R/C radio signal. The effects may include reduced remote control range
and/or induced errors in the command pulse resulting in jerky motor operation.
A higher quality PCM R/C transmitter/radio is recommended for all professional applica-
tions, as these are more immune to noise and interference.
While a more noise-immune radio system is always desirable, it is also recommended to
layout the wiring, the controller, radio and antenna so that as little as possible electrical
noise is generated. Section “Electrical Noise Reduction Techniques” on page 35 provides a
few suggestions for reducing the amount of electrical noise generated in your robot.
Joystick Deadband Programming
In order to avoid undesired motor activity while the joysticks are centered, the AX1500 sup-
ports a programmable deadband feature. A small deadband is set in the controller by
default at the factory. This deadband can be stretched, reduced or eliminated using the
Roborun utility. The AX1500 has 8 preset deadband values coded 0 to 7. The value 0 dis-
ables the deadband. Other values select a deadband according to the table below. The
deadband value applies equally to both joysticks.