ardupilot/libraries/AP_HAL_ChibiOS/hwdef/SIYI_N7

SIYI N7 Flight Controller

The SIYI N7 flight controller is sold by a range of resellers, linked from https://siyi.biz

Features

• STM32H743 microcontroller
• ICM20689 and BMI088 IMUs
• internal heater for IMU temperature control
• internal vibration isolation for IMUs
• MS5611 SPI barometer
• builtin IST8310 compass
• microSD card slot
• 4 UARTs plus USB
• 13 PWM outputs
• I2C and CAN ports
• RCIN port
• external safety Switch
• voltage monitoring for servo rail and Vcc
• power input port for external power bricks

Pinout

UART Mapping

• SERIAL0 -> USB
• SERIAL1 -> UART2 (Telem1)
• SERIAL2 -> unused
• SERIAL3 -> UART1 (GPS)
• SERIAL4 -> UART4 (GPS2, Telem4/I2C)
• SERIAL5 -> unused
• SERIAL6 -> UART7 (debug port)
• SERIAL7 -> USB2 (virtual port on same connector)

The Telem1 port has RTS/CTS pins, the other UARTs do not have RTS/CTS.

Connectors

Unless noted otherwise all connectors are JST GH

TELEM1 port

Pin	Signal	Volt
1 (red)	VCC	+5V
2 (blk)	TX (OUT)	+3.3V
3 (blk)	RX (IN)	+3.3V
4 (blk)	CTS	+3.3V
5 (blk)	RTS	+3.3V
6 (blk)	GND	GND

GPS1 port

Pin	Signal	Volt
1 (red)	VCC	+5V
2 (blk)	TX (OUT)	+3.3V
3 (blk)	RX (IN)	+3.3V
4 (blk)	SCL I2C1	+3.3V
5 (blk)	SDA I2C1	+3.3V
6 (blk)	Button	GND
7 (blk)	button LED	GND
8 (blk)	3.3V	3.3
9 (blk)	buzzer	GND
(blk)	GND	GND

GPS2, Telem4/I2C port

Pin	Signal	Volt
1 (red)	VCC	+5V
2 (blk)	TX (OUT)	+3.3V
3 (blk)	RX (IN)	+3.3V
4 (blk)	SCL I2C2	+3.3V
5 (blk)	SDA I2C2	+3.3V
6 (blk)	GND	GND

I2C

Pin	Signal	Volt
1 (red)	VCC	+5V
2 (blk)	SCL	+3.3 (pullups)
3 (blk)	SDA	+3.3 (pullups)
4 (blk)	GND	GND

CAN1

Pin	Signal	Volt
1 (red)	VCC	+5V
2 (blk)	CAN_H	+12V
3 (blk)	CAN_L	+12V
4 (blk)	GND	GND

POWER1

Pin	Signal	Volt
1 (red)	VCC	+5V
2 (red)	VCC	+5V
3 (blk)	CURRENT	up to +3.3V
4 (blk)	VOLTAGE	up to +3.3V
5 (blk)	GND	GND
6 (blk)	GND	GND

USB

Pin	Signal	Volt
1 (red)	VCC	+5V
2 (blk)	D_minus	+3.3V
3 (blk)	D_plus	+3.3V
4 (blk)	GND	GND

RC Input

RC input is configured on the RCIN pin, at one end of the servo rail, marked RCIN in the above diagram. This pin supports all RC protocols.

PWM Output

The SIYI N7 supports up to 13 PWM outputs. First first 8 outputs (labelled "MAIN") are controlled by a dedicated STM32F103 IO controller. These 8 outputs support all PWM output formats, but not DShot.

The remaining 5 outputs (labelled AUX1 to AUX5) are the "auxiliary" outputs. These are directly attached to the STM32H743 and support all PWM protocols as well as DShot.

All 13 PWM outputs have GND on the top row, 5V on the middle row and signal on the bottom row.

The 8 main PWM outputs are in 3 groups:

• PWM 1 and 2 in group1
• PWM 3 and 4 in group2
• PWM 5, 6, 7 and 8 in group3

The 4 auxiliary PWM outputs are in 2 groups:

• PWM 1, 2, 3 and 4 in group4
• PWM 5 in group5

Channels within the same group need to use the same output rate. If any channel in a group uses DShot then all channels in the group need to use DShot.

Battery Monitoring

The board has a dedicated power monitor ports on a 6 pin connector. The correct battery setting parameters are dependent on the type of power brick which is connected.

Compass

The SIYI N7 has one builtin IST8310 compass.

GPIOs

The 5 AUX PWM ports can be used as GPIOs (relays, buttons, RPM etc).

The numbering of the GPIOs for PIN variables in ArduPilot is:

• PWM1 50
• PWM2 51
• PWM3 52
• PWM4 53
• PWM5 54

Analog inputs

The SIYI N7 has 7 analog inputs

• ADC Pin16 -> Battery Voltage
• ADC Pin17 -> Battery Current Sensor

IMU Heater

The IMU heater in the SIYI N7 can be controlled with the BRD_HEAT_TARG parameter, which is in degrees C.

Loading Firmware

The board comes pre-installed with an ArduPilot compatible bootloader, allowing the loading of *.apj firmware files with any ArduPilot compatible ground station.