Tawaki/v2.01

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Hardware Revision History

Version #	Release Date	Release Notes
v2.01	03/2024	I2C 5V connector replaced by I2C 3.3V Solder jumper JP2 added for CAN bus resistor termination setup
v2.00	10/2023	Initial release of Tawaki v2

Overview

Pictures

• Tawaki v201 top pers.JPG
• Tawaki v201 bottom pers.JPG
• Tawaki v201 bottom hand.JPG
• Tawaki v201 top SD beside.JPG
• Tawaki v201 top x4.JPG

Key Features

• STMicro STM32H753VIH Micro Controller Unit
  • ARM Cortex-M7, 480 MHz CPU, FPU & DSP instructions, 2MBytes Flash, 1MB RAM, etc.
• On-board Sensors
  • 6 DOF Accelerometers & Gyrometers TDK-Invensense ICM-42688-P
  • 3 DOF Magnetometer STMicro LIS3MDL
  • Baro-Altimeter Bosch BMP390
• 8x Servos or ESC outputs: PWM/OneShot/DShot (+D-Shot Telemetry serial input)/DShot bidir
• 2x RC Receiver Inputs (S.BUS, PPM & Spektrum Satellite compatible, including receiver binding)
• Communication Buses
  • 3x UARTs (including one with hardware flow control signals)
  • 1x I2C bus (3.3V logic level, 2 connectors)
  • 1x SPI bus (with Slave Select, Master or Slave)
  • 1x CAN/CANFD bus
  • 1x USB-C (& remote) : DFU mode (download) or USB storage (direct access to MicroSD card) or FullSpeed Mode
• 8x Auxiliary Inputs/Outputs spread over 2 connectors (8x ADC, 8x Timers different from servos, x1 UART, etc.)
• MicroSD card (+ dedicated power supply for emergency files closing system)
• Debug Connector (Serial Wire Debug)
• Power
  • source 2 to 6 Lipo cells (6 to 26v)
  • 5V/5A (max total for Tawaki + Servos + Payload)
  • 3.3V/3A Low Noise (max total for payload)
  • Controlled PowerSwitch 5V/2A supply on AUX A connector
• x4 Status Leds
• Connectors fully compatible with Tawaki v1 & Apogee autopilot
• Mechanical
  • 53 x 25mm (2.1" x 0.98"), including 4x Φ2mm mounting holes (shares the same external dimensions and mounting points as Tawaki v1 & Apogee)
  • 4x Φ3mm extra mounting slotted holes, 30 to 31mm spacing (30.5mm standard from Racers ESC, GPS modules, etc. )
  • 11g (0.4 oz) (including Micro-SD card)

Pinout

Simplified Pinout Diagram (Paparazzi use)

Pins Name and Type are specified with respect to the Autopilot Board

Simplified Pinout Tables (Paparazzi use)

Servos a1 / a2 / a3 / a4

Pin #	Name	Type	MCU Port	Primary MCU Resource	Description
1	GND	PWR	-	-	common ground
2	+5V	PWR	-	-	5V Rail from autopilot
3	SRVa1 SRVa2 SRVa3 SRVa4	OUT	PE9 PE11 PE13 PE14	Tim1.Ch1 Tim1.Ch2 Tim1.Ch3 Tim1.Ch4	Servo signal (PWM)

Servos b

Pin #	Name	Type	MCU Port	Primary MCU Resource	Description
1	GND	PWR	-	-	common ground
2	VBAT	PWRIN/OUT	-	-	Battery Rail (if solder bridge JP1 ON)
3	SRVb1	OUT	PB6	Tim4.Ch1	Servo signal (PWM)
4	SRVb2	OUT	PB7	Tim4.Ch2	Servo signal (PWM)
5	SRVb3	OUT	PB8	Tim4.Ch3	Servo signal (PWM)
6	SRVb4	OUT	PB9	Tim4.Ch4	Servo signal (PWM)
7	DSHTin	IN	PA10	UART1.Rx	DShot Telemetry serial input

R/C

Pin #	Name	Type	MCU Port	Possible MCU Resource	Description
1	GND	PWR	-	-	common ground
2	+5V	PWR	-	-	5V Rail from autopilot
3	+3.3V	PWR	-	-	3.3V Rail from autopilot
4	RC1	IN	PE0	UART8.Rx	(5V Tolerant) Serial (SBUS, Spektrum, etc.)
5	RCaux	I/O	PC6	UART6.Tx Tim3.Ch1 Tim8.Ch1	(5V Tolerant) Serial (SBUS, Spektrum, etc.) or PPM Stream RC receiver signal

UART2

Pin #	Name	Type	MCU Port	Description
1	GND	PWR	-	common ground
2	+5V	PWR	-	5V Rail from autopilot
3	+3.3V	PWR	-	3.3V Rail from autopilot
4	RX2	IN	PD6	UART2 Serial Input (3.3V level)
5	TX2	OUT	PD5	UART2 Serial Output (3.3V level)

UART3

Pin #	Name	Type	MCU Port	Description
1	GND	PWR	-	common ground
2	+5V	PWR	-	5V Rail from autopilot
3	+3.3V	PWR	-	3.3V Rail from autopilot
4	RX3	IN	PD9	UART3 Serial Input (3.3V level)
5	TX3	OUT	PD8	UART3 Serial Output (3.3V level)

UART7

Pin #	Name	Type	MCU Port	Description
1	GND	PWR	-	common ground
2	+5V	PWR	-	5V Rail from autopilot
3	+3.3V	PWR	-	3.3V Rail from autopilot
4	RX7	IN	PB3	UART7 Serial Input (3.3V level)
5	TX7	OUT	PA15	UART7 Serial Output (3.3V level)

I2C2 (x2)

Pin #	Name	Type	MCU Port	Description
1	GND	PWR	-	common ground
2	+5V	PWR	-	5V Rail from autopilot
3	+3.3V	PWR	-	3.3V Rail from autopilot
4	SDA2	Open Drain I/O	PB11	I2C2 bus Serial DAta (3.3V level, 2.2kΩ pull-up)
5	SCL2	Open Drain I/O	PB10	I2C12 bus Serial CLock (3.3V level, 2.2kΩ pull-up)

SPI2

Pin #	Name	Type	MCU Port	Description
1	GND	PWR	-	common ground
2	+5V	PWR	-	5V Rail from autopilot
3	+3.3V	PWR	-	3.3V Rail from autopilot
4	NSS2	I/O	PB12	SPI2 Slave Select. Selects the SPI slave
5	MOSI2	I/O	PB15	SPI2 Master Out Slave In. Data output from master / data input to slave
6	MISO2	I/O	PB14	SPI2 Master In Slave Out. Data input to master / data output from slave
7	SCK2	I/O	PD3	SPI2 Serial clock. Clock output from master or input to slave

CAN FD

Pin #	Name	Type	MCU Port	Description
1	CANL	I/O	-	CAN FD bidirectional - line
2	CANH	I/O	-	CAN FD bidirectional + line

Note: solder JP2 to enable embedded 120Ω terminator resistor

AUX a

Pin #	Name	Type	MCU Port	Possible MCU Resource	Description
1	GND	PWR	-	-	common ground
2	+5V Aux	PWR	(Controlled by) PC13	-	5V from autopilot through Power Switch (PC13 = Low => OFF / PC13 = High => ON)
3	+3.3V	PWR	-	-	3.3V Rail from autopilot
4	AUXa1	I/O	PA0	ADC1.InP16 Tim2.Ch1 Tim5.Ch1 UART2.CTS UART4.Tx	General Purpose I/O
5	AUXa2	I/O	PA1	ADC1.InP17/N16 Tim2.Ch2 Tim5.Ch2 UART2.RTS UART4.Rx	General Purpose I/O
6	AUXa3	I/O	PA2	ADC1/2.InP14 Tim2.Ch3 Tim5.Ch3 UART2.Tx	General Purpose I/O
7	AUXa4	I/O	PA3	ADC1/2.InP15 Tim2.Ch4 Tim5.Ch4 UART2.Rx	General Purpose I/O

AUX b

Pin #	Name	Type	MCU Port	Possible MCU Resource	Description
1	GND	PWR	-	-	common ground
2	+5V	PWR	-	-	5V Rail from autopilot
3	+3.3V	PWR	-	-	3.3V Rail from autopilot
4	AUXb1	I/O	PA6	ADC1/2.InP3 Tim3.Ch1 Tim13.Ch1 SPI1.MISO SPI6.MISO	General Purpose I/O
5	AUXb2	I/O	PA7	ADC1/2.InN3/P7 Tim3.Ch2 Tim14.Ch1 SPI1.MOSI SPI6.MOSI	General Purpose I/O
6	AUXb3	I/O	PB0	ADC1/2.InN5/P9 Tim3.Ch3 UART4.CTS	General Purpose I/O
7	AUXb4	I/O	PB1	ADC1/2.InP5 Tim3.Ch4	General Purpose I/O

USB FS

Pin #	Name	Type	MCU Port	Description
1	GND	PWR	-	common ground
2	D+	I/O	PA12	USB Full Speed bidirectional D+ line
3	D-	I/O	PA11	USB Full Speed bidirectional D- line
4	VBUS	IN	PA9	USB bus power (5V)
5	BOOT	IN	BOOT0	DFU or USB Mode selection (BOOT0 MCU pin)

Note: USB-C Receptacle and Molex Picoblade connectors are in parallel, only one should be connected at a time.

SWD

Pin #	Name	Type	MCU Port	Description
1	GND	PWR	-	common ground
2	+3.3V	PWR	-	3.3V Rail from autopilot
3	nRST	IN	NRST	MCU Reset (active low)
4	SWCLK	IN	PA14	Serial Wire Clock
5	SWDIO	I/O	PA13	Serial Wire Data Input/Output

Detailed Features

Power Supply

There are several ways to power the Tawaki board. CAUTION! use only one of these sources at a time:

• with a battery or any power source that delivers between 6 and 26V
• by connecting it to a USB port
• with a power source that delivers a regulated, stable 5V

Each of these methods is detailed below.

Powering using battery/external source soldered onto battery pads

This is the basic setup: the Tawaki then generates all the internal power sources needed by its components. Additionally, the board provides +5V and +3.3V power sources through dedicated ports for external payload.
Limitations:

• input power source range: 6-26V (2-6 Lipo cells)
• maximum current usable by both Tawaki and payload on the +5V: I_5V < 5A
• maximum current usable for payload on the +3.3V: I_3.3V < 3A
• maximum total current usable: (I_5V+I_3.3V) < 5A

With this setup, the external power source is available on the “VBAT” pin of the “Servos B” header - but only if solder bridge JP1 is jumped (turned ON) with a small blob of solder.
Limitation:

• maximum current on the “VBAT” pin: I_Vbat < 1A (because of the header’s specifications)

Powering using battery/external source connected on "Servos B" header

With this setup, the “GND”(-) and “VBAT”(+) pins of the “Servos B” header are used as the main entry ports for the external power source - but only if solder bridge JP1 is jumped (turned ON) with a small blob of solder. This can be interesting when the ESC already delivers the external power source voltage through its command and control signals (as is frequently the case on multi-rotors).
Limitations:

• input power source range: 6-26V (2-6 Lipo cells)
• maximum current on the “VBAT” pin: I_Vbat < 1A (because of the header’s specifications)

Powering using USB-C only

It is possible to power the Tawaki with only a host computer, through the USB-C cable. This setup allows to power the board and all its components, while at the same time flashing it.
In this case, the "VBUS" pin of the "USB FS" header must be connected to the "+5V" pin of any header that is equipped with one - with the exception of the "5Vaux" pin of the "AUX a" header.
Limitation:

• the host computer must be capable of providing the current needed for: powering the board, and any potential external payload. With a maximum limit of 1A (because of the header’s specifications)
  

Note: with this setup, the voltage of the external power source (VBAT) obviously cannot be measured by the micro-controller (MCU).

Powering using external 5V source

In some cases the external power source is out of range and cannot be used, but an external 5V power source is available (for example provided by the ESC). In this case, the external 5V power source must be connected to the "+5V" and "GND" pins of any header that are equipped with them - with the exception of the "5Vaux" pin of the "AUX a" header.
Limitations:

• the external 5V power source must be capable of providing the current needed for powering the Tawaki and any potential external payload. With a maximum limit of 1A (because of the headers' specifications)
• voltage range: depending on potential external payload 5V capability, 4-6V for Tawaki board only.
• the "VBUS" pin of the "USB FS" header must not be connected to the "+5V" pin of any header

Note: with this setup, the voltage of the external power source (VBAT) obviously cannot be measured by the micro-controller (MCU).

USB Modes

DFU Flash mode

There is two options to boot the autopilot in DFU mode in order to flash it:

1. push and maintain "BOOT" small button
2. plug USB cable (already host connected)

OR

1. push and maintain "BOOT" small button
2. turn on autopilot power source.
3. plug USB cable.

OR

USB Storage mode

USB Storage mode make autopilot's SDcard content easily available by host computer as for an Pendrive.
To enter in USB storage mode, simply connect it to host computer USB (no action on small button) :

• If autopilot power is OFF, a new external disk drive should be detected by host computer OS.
• If autopilot power is already ON and running, autopilot task is stopped and board enters in USB storage mode. When unmounted and unplugged, autopilot task restart.

Wiring vs Button

For all previous USB modes, small "BOOT" push-button action can be replaced by shorting pin #4 (VBUS) and pin #5 (BOOT) of "USB FS" header.
In these configurations (button pushed or pin# 4 & 5 connected), BOOT0 pin of the STM32 MCU is connected to VBUS pin.
This "USB FS" header arrangement allow to wire a "remote" USB interface (USB receptacle + mode push-button) reasonably distant from autopilot board.

Detailed Pinout

Pins Name and Type are specified with respect to the Autopilot Board

Schematic

Mechanical

Mechanical Dimensions

CAD Files / 3D Model

Download Tawaki v1.00 CAD File (zipped STEP file)

Board production

Hardware Source Files

Tawaki v1.10 hardware design (zipped Kicad 8 project) : Tawaki_v110.zip

Components Layout

Bottom components layout (pdf)
Top components layout (pdf)

Source code

Available in latest git master branch.

Where to Buy

Check availability on Get Hardware page