Snapdragon Flight Autopilot

The Snapdragon Flight platform is a high-end autopilot / onboard computer which runs the PX4 Flight Stack on the DSP on the QuRT real time operating system using the DSPAL API for POSIX compatibility. In comparison to Pixhawk it adds a camera and WiFi and high-end processing power, and different IO.

More information about the Snapdragon Flight platform is at Snapdragon-Flight-Details

Quick Summary

  • System-on-Chip: Snapdragon 801
    • CPU: Quad-core 2.26 GHz Krait
    • DSP: Hexagon DSP (QDSP6 V5A) – 801 MHz+256KL2 (running the flight code)
    • GPU: Qualcomm® Adreno™ 330 GPU
    • RAM: 2GB LPDDR3 PoP @931 MHz
  • Storage: 32GB eMMC Flash
  • Video: Sony IMX135 on Liteon Module 12P1BAD11
    • 4k@30fps 3840×2160 video capture to SD card with H.264 @ 100Mbits (1080p/60 with parallel FPV), 720p FPV
  • Optic Flow: Omnivision OV7251 on Sunny Module MD102A-200
    • 640x480 @ 30/60/90 fps
  • Wifi: Qualcomm® VIVE™ 1-stream 802.11n/ac with MU-MIMO † Integrated digital core
  • BT/WiFi: BT 4.0 and 2G/5G WiFi via QCA6234
    • 802.11n, 2×2 MIMO with 2 uCOAX connectors on-board for connection to external antenna
  • GPS: Telit Jupiter SE868 V2 module (use of an external u-Blox module is recommended by PX4 instead)
    • uCOAX connector on-board for connection to external GPS patch antenna
    • CSR SiRFstarV @ 5Hz via UART
  • Accelerometer / Gyro / Mag: Invensense MPU-9250 9-Axis Sensor, 3x3mm QFN, on bus SPI1
  • Baro: Bosch BMP280 barometric pressure sensor, on bus I2C3
  • Power: 5VDC via external 2S-6S battery regulated down to 5V via APM adapter
  • Availability: Intrinsyc Store

We use the Snapdragon Flight with the following setup.

Components

Details on wiring can be found below.

Connectivity

  • One USB 3.0 OTG port (micro-A/B)
  • Micro SD card slot
  • Gimbal connector (PWB/GND/BLSP)
  • ESC connector (2W UART)
  • I2C
  • 60-pin high speed Samtec QSH-030-01-L-D-A-K expansion connector

Pinouts

Warning Although the Snapdragon uses DF13 connectors, the pinout is different from Pixhawk.

Detailed pinout information can be found here: Qualcomm Developer Network.

WiFi

Connectors

The default mapping of the serial ports is as follows:

Device Description
/dev/tty-1 J15 (next to USB)
/dev/tty-2 J13 (next to power module connector)
/dev/tty-3 J12 (next to J13)
/dev/tty-4 J9 (next to J15)

For a custom UART to BAM mapping, create a file called "blsp.config" and adb push it to /usr/share/data/adsp. E.g., to keep the default mapping, your "blsp.config" should look as follows:

tty-1 bam-9 2-wire
tty-2 bam-6 2-wire
tty-3 bam-8 2-wire
tty-4 bam-2 2-wire

Be sure to include the text "2-wire" at the end of each line to allow the UART to use only the TX and RX pins specified in the tables below. If 2-wire is not specified (or if the file is not present on the target) the UART will default to using 4-wire mode and will require an additional two pins for RTS/CTS flow control. This will cause a problem for any other type of I/O on the same connector, since the pins will be configured as RTS and CTS signals. If, for example, J9 (described below) was being used to connect to both a UART and an I2C device, the I2C signals on pin 4 and pin 6 would be configured as RTS and CTS signals, overriding the I2C SDA and SCL signals.

J9 / GPS

Pin 2-wire UART + I2C 4-wire UART SPI Comment
1 3.3V 3.3V 3.3V
2 UART2_TX UART2_TX SPI2_MOSI Output (3.3V)
3 UART2_RX UART2_RX SPI2_MISO Input (3.3V)
4 I2C2_SDA UART2_RTS SPI2_CS (3.3V)
5 GND GND GND
6 I2C2_SCL UART2_CTS SPI2_CLK (3.3V)

J12 / Gimbal bus

Pin 2-wire UART + GPIO 4-wire UART SPI Comment
1 3.3V 3.3V 3.3V
2 UART8_TX UART8_TX SPI8_MOSI Output (3.3V)
3 UART8_RX UART8_RX SPI8_MISO Input (3.3V)
4 APQ_GPIO_47 UART8_RTS SPI8_CS (3.3V)
5 GND GND GND
6 APQ_GPIO_48 UART8_CTS SPI8_CLK (3.3V)

J13 / ESC bus

Pin 2-wire UART + GPIO 4-wire UART SPI Comment
1 5V 5V 5V
2 UART6_TX UART6_TX SPI6_MOSI Output (5V)
3 UART6_RX UART6_RX SPI6_MISO Input (5V)
4 APQ_GPIO_29 UART6_RTS SPI6_CS (5V)
5 GND GND GND
6 APQ_GPIO_30 UART6_CTS SPI6_CLK (5V)

J14 / Power

Pin Signal Comment
1 5V DC Power input
2 GND
3 I2C3_SCL (5V)
4 I2C3_SDA (5V)

J15 / Radio Receiver / Sensors

Pin 2-wire UART + I2C 4-wire UART SPI Comment
1 3.3V 3.3V 3.3V
2 UART9_TX UART9_TX SPI9_MOSI Output
3 UART9_RX UART9_RX SPI9_MISO Input
4 I2C9_SDA UART9_RTS SPI9_CS
5 GND GND GND
6 I2C9_SCL UART9_CTS SPI9_CLK

Peripherals

GPS Wiring

Even though the 3DR GPS is described to have a 5v input, operation with 3.3V seems to work fine. (The built-in regulator MIC5205 has a minimum operating voltage of 2.5v.)

Snapdragon J9 Pin Signal Comment 3DR GPS 6pin/4pin Pixfalcon GPS pin 3DR PIXHAWK MINI GPS
1 3.3V (3.3V) 1 4 3 (5V)
2 UART2_TX Output (3.3V) 2/- 3 4
3 UART2_RX Input (3.3V) 3/- 2 5
4 I2C2_SDA (3.3V) -/3 5 2
5 GND 6/- 1 6
6 I2C2_SCL (3.3V) -/2 6 1

PWM ESC Wiring

For controlling the motors, PWM ESCs can be used. Use connector J13 (next to power module connector) and the following wiring. ESC numbers is according to here.

Snapdragon J13 Pin ESC Comment
1 - They already have voltage
2 1 Signal (orange)
3 2 Signal (orange)
4 3 Signal (orange)
5 GND GND from all ESCs
6 4 Signal (orange)

RC Wiring

Snapdragon J12 Pin Spektrum receiver (3 pins)
1 3.3 V
2 -
3 Signal
4 -
5 GND
6 -

Trone Range Finder Wiring

Snapdragon J15 Pin Trone (4 pins)
1 1
2 -
3 -
4 3
5 4
6 2

Details can be found here

UART to Pixracer / Pixfalcon Wiring

This interface is used to leverage the Pixracer / Pixfalcon as I/O interface board. Connect to TELEM1 Pixfalcon and to TELEM2 on Pixracer.

Snapdragon J13 Pin Signal Comment Pixfalcon / Pixracer Pin
1 5V Power for autopilot 5V
2 UART6_TX Output (5V) TX -> RX 3
3 UART6_RX Input (5V) RX -> TX 2
4 APQ_GPIO_29 (5V) Not connected
5 GND 6
6 APQ_GPIO_30 (5V) Not connected

Dimensions

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