SBUS2-Telemetry Library

Arduino Library for receiving SBUS and SBUS2 Frames and transmit Telemetry Data

• with Atmega328P MCU
  • The Library uses the U(S)ART Interrupt and Timer2
  • You can't use Serial in your Sketch! Please use Softserial instead.
• with ESP32
  • The Library uses Serial1 (UART_NUM_1) and TIMER_1 in TIMER_GROUP_0
  • RX1 = GPIO_NUM_25 and TX1 = GPIO_NUM_26
  • Serial, Timer and RX/TX Pins can be changed

Setting up the Example Sketch

• Before you start flashing and coding, please Setup you Futaba Radio Control
  • Select Modulation-> FASSTest -> 14CH and bind your Receiver
  • You should see the SerialNumber of the Receiver
  • In Telemetry Screen, you should see the RX Voltage
  • Got to "Sensors" Menu and activate the Inactive Slots
  • See #defines in the example Sketch -> #define TEMPRATURE_SLOT 1
  • Set Slot1 (Inactive) to Temp125 Sensor
  • Do the same with all other Sensors defined in the Example Sketch
• Build up you Arduino Hardware with Atmega328P
  • Build your Inverter Circuit
  • Flash the Sktech -> On Arduino Pro Mini you must flash without attached Inverter!
  • Attach The Inverter to RX and TX on the Arduino Board
  • Attach the Inverter to SBUS2 Port on your Receiver
• Build up you Arduino Hardware with ESP32
  • Place 1k between your RX1 and TX1 Pins
  • Attach the SBUS2 Port to RX1 Pin
  • Flash the Sktech
• Power up
  • You can power your Futaba Receiver from Arduino (5V)
  • Or you power your Arduino from Futaba Receiver (BEC)
  • You will See Telemetry Data on your Telemetry Screen

Setting up a custom Sketch

You can't set every Sensor to every Slot! There are Sensors which use 1 Slot and other Sensors use 3 or 8 Slots.

After receiving the SBUS Frame it's possible to transmit 8 Telemetry Slots.

There are 32 different Telemetry Slots available.

Example

• Slot 0 is always RX Voltage-> So you cant use Slot0 for custom Sensors
• So you have 7 Slots left (Slot 1 to Slot 7)
• So you cant use a 8 Slot Sensor (GPS) on Slot 1!
• GPS has to be on Slot 8, or Slot 16, or Slot 24
• On Slot 1 you could set a Temperature Sensor (1 Slot Sensor)
• On Slot 2 you could set a RPM Sensor (1 Slot Sensor)
• On Slot 3 you could set a Power Sensor (3 Slot Sensor)
• The Power Sensor uses Slot 3, Slot 4 and Slot 5 (3 Slot's!)
• The next free Slot would be Slot 6
• Slot 6 can't be a Power Sensor, because you have just 2 Slots free!

The easiest Way for a Working Setup

• First set all Sensors in your Futaba Radio Control
• Your Futaba System will keep the things clear.
• After you set up all your Favorit Sensors in your Radio, you can #define the used Slot's in the Sketch
• Take a look which Radio support which Sensor

Structure

You can use every Sensor as often you want. But you have a maximum of 31 Sensor Slots If yo want to have multiple Temp Sensors, just change the Slot Number:

• send_temp125(TEMPRATURE_SLOT1, (int16_t)50);
• send_temp125(TEMPRATURE_SLOT2, (int16_t)80);
• send_temp125(TEMPRATURE_SLOT3, (int16_t)20);
• send_temp125(TEMPRATURE_SLOT4, (int16_t)999);
  • The same for all other Sensors The Sensor Values are updated with your Loop() cycle time.
• If your loop() contains a Delay(2000), your Telemetry Data will be updated every 2sek
• If your loop() has no Delay's, your Telemetry Data will be updated every 60ms (every 4 SBUS Frames)
• The Servo Channel Data is updated every 15ms (with every new SBUS(2) Frame)

Stand alone SBUS Library

This Library can be used just for getting Servo Channel Data. The Library just send telemetry Data to SBUS2 compatible Receiver.

• SBUS_Ready() -> True when new Servo data is received with SBUS and SBUS2 Frames
• SBUS2_Ready() -> True when SBUS2 Frames are received
• SBUS2_get_status() will also work with just SBUS Frames

Supported Sensors

• Temp125 -> Temperatures from -16384°C to + 16383°C
• SBS/01TE -> Temperatures from -16384°C to + 16383°C
• F1713 -> Temperatures from -16384°C to + 16383°C
• SBS/01T -> Temperatures from -100°C to + 32667°C
• SBS-01RM -> Rotations per Minute (RPM) from 0 to 393210
• SBS/01RB -> Rotations per Minute (RPM) from 0 to 393210
• SBS-01RO -> Rotations per Minute (RPM) from 0 to 393210
• Curr-1678 -> Voltage (0V to 655.3V) / Current (0A to 163.0A) / Capacity Sensor (0mAh to 32767 mAh)
• F1678 -> Voltage (0V to 655.3V) / Current (0A to 163.0A) / Capacity Sensor (0mAh to 32767 mAh)
• GPS-1675 -> Speed (0km/h to 999km/h) / Altitude (-16384m to +16383m) / Vario (-3276.8m/s to +3276.7m/s) / LON&LAT (Degree Minutes)
• F1675 -> Speed (0km/h to 999km/h) / Altitude (-16384m to +16383m) / Vario (-3276.8m/s to +3276.7m/s) / LON&LAT (Degree Minutes)
• SBS-01G -> Speed (0km/h to 511km/h) / Altitude (-820m to +4830m) / Vario (-150m/s to +260m/s) / LON&LAT (Degree Minutes)
• SBS/01V -> Voltage (0V to 819.1V) / Voltage (0V to 819.1V)
• F1672 -> Vario (-327.6m/s to +327.6m/s) / Altitude (-16384m to +16383m)
• F1712 -> Vario (-3276,8m/s to +3276.7m/s) / Altitude (-16384m to +16383m)

Unsupported Sensors:

• SBS/01S
• SBS-0 1 TAS
• F1677
• SBS/01C
• P-SBS/01T
• SBS/02A
• SBS/01A

Supported Radio Systems

• T14SG
• T18MZ
• T10J
• ...

Supported Receivers

• R7003SB
• R7008SB
• R3006SB
• ...

Supported MCU

• Arduino Pro Mini 8MHz (with external Inverters)
• Arduino Pro Mini 16MHz (with external Inverters)
• ESP32
• ...

Inverter Schematic for Atmega328P (Arduino Pro mini)

Guide for Library Development

The Futaba Telemetry Protocol has very hard Timings:

• Slot 0 must be send 2ms after the last Byte of the SBUS(2) Frame
• same for Slot 8, Slot 16 and Slot 24
• After every Slot's there must be 325µs Pause to the next Slot
• So you have to receive the SBUS Frame in a UART Interrupt
• And with the Last Byte of the Frame you have to Start a Timer with 2ms
• With every Timer Interrupt you have to set the next Timer Interrupt to 660µs
• If the Timer doesn't work in this conditions, you do not need to start developing the Slot data transmission
• You need to have a Logic Analyser or Oscilloscope
• The best way is to toggle some Pins to check the correct timing
• SBUS(2) Level Voltage is 3,3V -> Do not work with 5V Level Signals!

Aditional Informations about Futaba's SBUS and SBUS2

• SBUS(2) is 100000 Baud with 8 data bits, even parity and 2 stop bits
• SBUS(2) Signal is inverted UART
• SBUS is a Frame with 25 Bytes
  • Byte [0] is 0x0F
  • Byte [1-22] is Servo Channel Data
  • Byte [23] is DigiChannel 17&18 + Stus Bits
  • Byte [24] is 0x00
• SBUS2 is a SBUS Frame but with a diffent End Byte (Byte24)
  • Byte [24] is 0x04, 0x14, 0x24, 0x34
  • Byte 24 controls the Number of the Telemetry Slot's
  • 0x04 -> Slot 0 to Slot 7
  • 0x14 -> Slot 8 to Slot 15
  • 0x24 -> Slot 16 to Slot 23
  • 0x34 -> Slot 24 to Slot 31

Version

0.1 created

0.2 Inverter instead of 3-State Buffer

0.3 16MHz support, new API

1.0 Pre-Release

1.0 Release

1.1 ESP32 Support

1.2 Available in Arduino Library Manager

Credentials

Bart Keser with his Castle Creation Telemetry to Futaba Telemetry Converter

Alex K. and his Development