When it comes to miniaturization, few RC receivers can match the SPM9545 satellite receiver made by Spektrum. Measuring only 0.98" x 0.89" x 0.27", this inexpensive 2.4GHz spread spektrum receiver is normally used as a backup to a master RC receiver in a typical system. It is however a fully functional receiver and differs only by the absence of the bulky headers normally used to connect the battery and servos. The receiver uses only 3 wires for ground, 3.3V power, and serial data output. The high speed serial stream that is output by the receiver digitally encapsulates the value of up to 6 transmitter channels (joystick & switch positions).
The SDC2130/2150 controller has a special 3-pin connector that is compatible with the Spektrum radio, to supply its power and retrieves its data. When the Spektrum mode is enabled, the controller captures and parses the serial stream in order to decodes each of these channels.
Using the Roborun PC utility, each motor channel can be assigned to any one of the 6 receiver channels .Additionally, the minimum, maximum, center and deadband values can be independently set for each channel in order to obtain the best possible response to joystick commands.
The command priority mechanism of the SDC2130 also works with the Spektrum radio. Like all other NxtGen Roboteq controllers, the SDC2130 will accept, in addition to the Spektrum receiver, commands from either the RS232 port, USB port, RC pulse inputs and Analog inputs. Depending on the priority definition, the controller will automatically switch from one command mode to the other. For example, an autonomous robot commanded by an onboard navigation computer can be made to switch to manual remote control command as soon as the Spektrum transmitter is turned on.
The raw 10-bit data from each of the 6 Spektrum receiver data can be read from the RS232 or USB port using simple queries. Likewise the raw data can be read from within a MicroBasic script running on the controller. This feature makes is possible to use the 4 extra channels in order to activate special function or change operating parameters on the fly.