This  project  allows  to  generate bidirectional  DSHOT  protocol  to
control ESCs via the GPIO pins of  a Raspberry Pi 5.  It uses 'piolib'
and RP1 coprocessor to generate  the signal and scan telemetry frames.
It works well even if the main CPU is loaded by other tasks.

It supports up to 28 motors.  However, motors shall be connected to up
to 4 continuous ranges of GPIO numbers.

All versions  of bidirectional DSHOT  (300 /  600 / 1200)  should work
(1200  was not  tested).   The specific  version has  to  be set  into
'dshotVersion' variable prior to the initialization.

Bidirectional DSHOT allows  to control motors and  read telemetry data
from  ESC on  a single  line.  Telemetry  includes rotation  speed and
optionally  temperature, voltage  and current.   Note that  the update
rate   of  bidirectional   DSHOT  is   much  smaller   than  that   of
unidirectional DSHOT mainly due to line switching constraints.

Some code used in this project comes from Joseph Duchesne's project:
https://github.com/josephduchesne/pico-dshot-bidir

You  will need  the  newest  version of  Raspbian  OS  and the  newest
bootloader version (see the ‘Advanced Options’ of raspi-config) to run
this code.

To compile and run a simple test that spins 2 motors connected to GPIO
18 and 19, type:

    	   make test
	   pinctrl set 18 op dl && pinctrl set 19 op dl && sleep 5 # possibly reset ESC
	   sudo ./test 18 19

If it does not work for your  ESC you may need to edit 'motor-bidshot.c'
and adjust DSHOT_CLOCK_DIVIDER_FACTOR macro.