This library provides mbed support for Spektrum serial receivers. So far, the library has been tested on a Spektrum SPM9745 DSMX remote receiver (since v1.0.0), and will probably be tested on a SPM9645 in the near future.
Source code is revision controlled using Git and hosted in a Github repository.
git clone ssh://git@github.com/devangel77b/Spektrum.git
git pullThe dev branch is bleeding edge; master branch is reasonably up to date.
The main part of the library are two classes for Spektrum (receiver) and BindPlug, which allows binding a transmitter to the receiver. In addition, a convenience macro for converting 0-2048 values to PwmOut pulsewidths (600-2100us, centered at 900us) is provided (SPEKTRUM_COUNT2US()).
The specification for Spektrum Remote Receiver Interfacing, rev A, 12 Apr 2016, has a note about servo position ranges:
A full range of servo position data ranges from 0-1024 or 0-2045 depending on the bind type. These limits are equivalent to a +/-150% travel setting in AirWare. This full range translates to a range of 1194us which when applied to a pwm servo signal equals 903-2097us. At +/-100% travel, the data range is equivalent to a servo position data range of approximately 341 to 1707 which translated to pwm equals 1102 us to 1898 us.
D Evangelista
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The code is based on an earlier Spektrum code by M Nentwig, [https://os.mbed.com/users/offroad/code/spektRx/], however, that code appears to have used an earlier version of Spektrum standard that appears no longer to cover the serial Satellite and DSMX quad race receivers.
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"Spektrum Remote Receiver Interfacing", rev A, dtd 12 Apr 2016 [https://www.spektrumrc.com/ProdInfo/Files/Remote%20Receiver%20Interfacing%20Rev%20A.pdf], however, there are some slight differences between what is described there and what was observed when probing a SPM9745 DSMX remote receiver.