Allows a script to simulate a device attached via any serial protocol.
The script can read and write data and have it handled according to the
protocol as if exchanged over a serial port. The script can then do
protocol translation, data filtering and validation,
hardware-in-the-loop simulation, experimentation, etc., especially in
combination with the scripting protocol which lets the script itself
handle an attached device and so interpose any communication.
Using `luaL_Buffer` avoids the need for any heap allocation in the
common case (count <= 512 bytes) and avoids stressing out the system
heap for large reads, instead using the script heap.
Zero net flash usage change.
Adding another layer instead of just exposing UARTDriver bindings allows
substitution of the different functions for device simulation later.
Also take the opportunity to rework the docs a little.
Passing -1 to the argument count for the `creation` tag (name does not
matter) will stop the generator from giving Lua a function to construct
that userdata. The C `new_<name>` function still works.
This script uses the scaled output from the antennatracker servos and map them to corresponding Pelco-D messages to be sent via a RS-485 interface to a motorized base (can be anything from motorized tracker to a PTZ camera).
If your FCU doesnt offer a RS-485 interface by default, you can use or TTL-RS485- or USB-RS485-adapters.
Pelco-D allows to control using either speed-/differential- or absolute-control control of the pan-/tilt-axis.
Currently the script uses speed based control using by mapping the "ContinuousRotation" type servos outputs to the corresponding Pelco-D messages.
The absolute control messages are implemented nevertheless for future use.
The script assumes therefor at least the following parameters to be set:
SCR_ENABLE = 1
SERVO_PITCH_TYPE = 2 # ContinuousRotation type servo
SERVO_YAW_TYPE = 2 # ContinuousRotation type servo
SERIALx_PROTOCOL = 28 # serial port used by luascript
Additionally the PITCH2SRV and YAW2SRV tuning needs to be done as described by the antennatracker description.
Also keep attention to the PITCH_MIN, PITCH_MAX and YAW_RANGE parameters to fit your Pelco-D hardware!
the register save must happen before the setjmp() call, which means
outside of the LUAI_TRY() macro. We also should be saving all 32
floating point registers