This is an ATMEL Mega328P / NRF24L01+ based 2.4GHz radio receiver

Features:

Compatible with this transmitter: https://github.com/TheDIYGuy999/RC_Transmitter
Programmable with Arduino IDE
4 RC servo connectors
SBUS output
Outputs for Headlights, indicators, taillights with brake lights
Additional switching output
Support for self balancing robot or car with stability control (using an MPU-6050 sensor)
Integrated TB6612FNG dual dc motor driver
Serial header (with SBUS support)
I2C header (for example for the supported MPU-6050)
ICSP header for programming with Arduino IDE (use "TheDIYGuy999 328P" board definition and set brownout voltage to 1.8V)
NRF24L01+ SMD module integrated
very small size
Up to 20 vehicle addresses selectable, allows to use the same remote controller for 10 vehicles
Eagle & Gerber files are also provided, if you want to build your own receiver!

See: https://www.youtube.com/playlist?list=PLGO5EJJClJBCjIvu8frS7LrEU3H2Yz_so

New in V 1.3:

Vehicle configuration is now stored in "vehicleConfig.h", so the main code always stays the same.
Crude frequency hopping, if bad receiving quality is detected (needs to be improved).

New in V 1.4:

10 vehicle addresses instead of 5
More vehicle configuration options
The "BACK" button on the transmitter can now be used (if the menu screen is not displayed on the OLED) as a momentary button, for example for a horn on the vehicle. It is sent as "data.momentary1"
SimpleTimer library replaced with my own code, which uses significantly less memory

New in V 1.5:

Added steering mixer for semi caterpillar and caterpillar vehicles such as tanks, diggers etc.
Channel 3 is throttle, channel 1 is steering
More vehicle configuration options in vehicleVonfig.h
The left caterpillar is motor 2, the right is motor 1
Steering servo 1 can be used in parallel (for semi caterpillar vehicles or vehicles with electronic differential)

New in V 1.6:

Added indicator lights - wired to A4 (SDA) / A5 (SCL) ports
enabled and disabled left / right by channel 4 left / right
disabled by turning back the steering wheel (channel 1) - just like a real car
hazard lights (all indicators flashing), if no connection to the transmitter

New in V 1.61:

Battery cutoff bug fixed

New in V 1.7 (Support for board revision 1.3):

**** TB6612FNG library update to V1.1 is required! ****
motor driver pinout has changed in board V1.3. So we are now able to adjust the PWM frequency of motor2. This allows smooth motor operation without the typical PWM whining.
vehicleConfig.h changed: "boardVersion" and "HP" variables added. They allow to stay compatible with older board versions. Just select the correct configuration.
The new "HP" (High Power) board version has only one motor driver channel, because both TB6612FNG channels are wired in parallel. It's able to supply 2.4A (average) / 6.4A (peak) so we can use bigger motors. This is useful for models, which use a steering servo and don't need a second motor channel.'
automatic radio re-initialisation after signal timeout

New in V 1.71

Battery monitoring and cutoff triggering improved. Under load, 0.3V are now added to the battery voltage to compensate the voltage drop. This allows to set the cutoff voltage to 3.6V, even with bigger loads.
Vehicle #7 added.

New in V 1.8

New "engineSound" variable in "vehicleconfig.h". True means, that the servo 3 pulse signal can be switched on and off, using the channel 2 joystick. This switches the engine sound on my "Rc Engine Sound" unit on and off.

New in V 1.9

New vehicle specific configuration section in vehicleConfig.h. The configuration is now done entirely during compilation time.

New in V 2.0

vehicle Config.h: New vehicleType 3 (forklift) added. Motor 2 is used as lifting motor in this case. A servo is required as steering motor.
Beacon lights can be wired to servo channel 4. Select "beacons = true" in this case. The beacons are flashing during vehicle movement and are switching off, after the vehicle did not move for 10s.

New in V 2.1

Sounds for a STAR WARS R2-D2 robot can now be generated on servo channel 3
"toneOut" variable added to vehicleConfig.h. True means, that servo 3 channel is generating sounds instead of a servo signal.
Do not enable "toneOut" and "engineSound" at the same time.
Note: the Arduino tone() function is blocking. So don't play sounds while driving ;-)

New in V 2.2

**** TB6612FNG library update to V1.2 is required! **** https://github.com/TheDIYGuy999/TB6612FNG
**** The PID library is required! **** https://github.com/br3ttb/Arduino-PID-Library/
Support for self balancing (inverted pendulum, segway) vehicles. See: https://www.youtube.com/watch?v=zse9-l2Yo3Y)
A MPU-6050 accelerometer & gyro module is used for the balancing data communication via SDA & SCL
Note, that the receiver will not work, if your vehicleType is 4 (balancing) and no MPU-6050 is connected!
Do not enable "balancing" and "indicators" at the same time.

New in V 2.21

Gyro drift calibration bug fixed
Changed the balancing controller refresh rate to 125Hz to reduce jitter on a 8MHz MCU. Reason: one program loop takes 4 - 7ms, so we can't use a time base of 4ms (=250Hz).

New in V 2.3

MRSC (Micro RC Stability Control) added. This functionality is similar to the Traxxas TSM or ESC. See: https://www.youtube.com/watch?v=IPve7QpdLBc&t=5s
The steering servo angle is compensated in accordance with the speed, the requested steering angle and the measured yaw rate, which is coming from the MPU-6050
Basically the mrsc() function was added. The required yaw rate is already calculated in the balancing.h, which is already existing for self balancing robots
If you want to use this functionality, you have to set the vehicleType to 5 in the vehicleConfig.h. Please note, that the receiver will not work, if no MPU-6050 is connected and the vehicleType is set to 4 or 5!

New in V 2.31

MRSC gain factor now depending on the potentiometer 1 value on the transmitter
Allows to fine adjust the MRSC during driving, depending on the requirements of the street surface
Note, that you need to connect a potentiometer to the analog input A6 of your transmitter!

New in V 2.32

Flickering headlights bug in vehicleType 5 fixed
The accelerometer vectors are not processed anymore in vehicleType 5. This is only required for the self balancing robot (vehicleType 4)

New in V 2.4

The I2C bus is scanned for an MPU-6050 sensor during the setup() sequence. The vehicleType is automatically changed to 0 (car without MRSC), if no sensor is detected.
This means, that a car with vehicleType 5 (MRSC Stability Control) can now also be used without an MPU-6050 plugged in.
Note, that the self balancing mode (vehicleType 4) always requires an MPU-6050. Otherwise the receiver will not start.

New in V 2.41

The "indicators" variable is now locked and can't be enabled, if the SDA and SCL pins are in use for the MPU-6050 sensor. This is the case in vehicleMode 4 and 5.

New in V 2.5

The MRSC stability control is now also working for cars without a steering servo
Code was added to control a DC steering motor (as found in cheap RC cars) in accordance with the MPU-6050 yaw rate
This is for example very useful for Coke Can Cars. See: https://www.youtube.com/watch?v=jr5yYBal3vk

New in V 2.6

The MRSC stability control can now be used with transmitters without gain adjustment potentiometer
The following optional parameters in the vehicleConfig.h allow to use a fixed gain: MRSC_FIXED, mrscGain
Allows to add an MPU-6050 gyro to every vehicle. So we always have a closed loop steering control, even without a proper servo with potentiometer feedback
On the "Non-High-Power" receiver model, 0.3V battery voltage are not added anymore during driving. This is not useful, if there is not much current draw.

New in V 2.7

The MRSC stability control gain adjustment knob can now be linked to servo CH4, if "potentiometer1" is set to "true" in vehicleConfig.h
This is useful, if an external MRSC stability control unit for 3 pin servos is used. See: https://github.com/TheDIYGuy999/MRSC_Adapter_3Pin_Servo
Servo CH4 is wired to pin 5 in this case. This allows to adjust the MRSC gain on the transmitter, just as with the internal MRSC stability control

New in V 2.8

Added support for differential thrust controlled airplanes
Tested with a Piper J3 CUB from Banggood

New in V 2.9

Added TWO_SPEED_GEARBOX option for mechanical two speed gearboxes, shifted by a servo, connected to CH2, controlled by "Mode 1" button
Example see vehicle CONFIG_WPL_B-36
See video: https://www.youtube.com/watch?v=EaOJE_GU5pk&t=1s

New in V 3.0

Added TRACTOR_TRAILER_UNLOCK option. Used to operate the tractor trailer unlocking servo
Press the "Back / Pulse" button to unlock your trailer
See vehicle "CONFIG_JJRC_Q60" for example
Parts for 3D printing: https://www.thingiverse.com/thing:3399449

New in V 3.1

Added THRE_SPEED_GEARBOX option for mechanical three speed gearboxes, shifted by a servo, connected to CH2, controlled by a 3 position switch, connected to CH2 Joystick input of the transmitter. A 10k resistor is reqired between GND and the input pin as well as between the input pin and VCC
Three individual servo positions can be programmed: lim2L, lim2C, lim2R
Example see vehicle CONFIG_HG_P407

New in V 3.2

Added the "TXO_toggle1" variable: allows to toggle the TXO pin, using the "Back / Impulse" button on the transmitter
Useful for example for additional lights
Don't activate it in combination with "TXO_momentary1". Serial is not usable, if one of these booleans is set to true

New in V 3.3

Added experimental support for serial communication with my "Arduino RC engine sound generator for ESP32": https://github.com/TheDIYGuy999/Rc_Engine_Sound_ESP32
Uncomment "#define SERIAL_COMMUNICATION" in Adjustments.h of the sound generator
Connect pin 36 "VP"of the sound generator to pin "TXO" of the receiver (disable "TXO_momentary1", "TXO_toggle1" & "headLights" in vehicleConfig.h)

New in V 3.31

"headlLights" must be inactive as well in order to use serial communication!

New in V 3.32

"data.pot1" properly initialized (cauesd an issue on the ESP32 engine sound generator)

New in V 3.4

SBUS support added (variable "SBUS_SERIAL" in vehicleConfiguration.h
Channel order and comments see sendSbusCommands()
You need to install my SBUS library: https://github.com/TheDIYGuy999/SBUS
Connect your servos or what ever to pin "TXO" (disable "TXO_momentary1", "TXO_toggle1" & "headLights" in vehicleConfig.h)

New in V 3.5

mode1, mode2 and momentary1 properly initialised before SBUS is enabled

New in V 3.6

"vehicleType" 1 or 2 (tracked or half tracked mode steering mixer) is now working as well, if two ESC are connected to servo pins 2 and 3. In the past, it was only usable with the internal TB6612 dual DC motor driver.
Also works in combination with my ESP32 Engine Sound & Light Controller (SBUS & PWM Mode)

New in V 3.7

Steering center position separately adjustable, using "#define STEERING_3_POINT_CAL" and "lim1C". This is useful for badly designed steering linkage geometries. Example see vehicle configuration "CONFIG_WPL_B_36_MODE1"

New in V 3.8:

20 vehicle addresses instead of 10
Less RAM usage
2 speed transmission not shifting while standing still. This will protect the shifting servo.

New in V 3.81:

Libraries comments added

New in V 3.9:

New "#define VEHICLE_TYPE_3_WITH_ESC" option for vehicle type 3. Allows to use both TB6612 FNG motor driver channels for other stuff
Used in "CONFIG_MECCANO_DUMPER"