droneOS

A Go framework for remotely and automatically flying a drone.

NOTE: This project is unstable and currently under development

Usage

Hardware

• You'll need one RPi for the drone. To make your life easiest, get the newest RPi Zero
• You need a PC for the base station
  • Technically, you can run this wherever you can get the software/hardware to work, which is left as an exercise for the reader.
  • You'll need a radio communication module that plugs in via USB
  • Joystick supported by gobot

Software

• Install build dependencies: bash setup.sh
• For each RPi, insert your SD card and run lsblk to find which /dev/sd# file it is
  • NOTE: running lsblk is important! Choosing the wrong drive will wreck the data!
• Unmount the SD card if it's mounted: sudo umount /dev/sd#1 && sudo umount /dev/sd#2
• Build the image like this: bash build_image.sh sd# kernel base username userpassword ssid ssidpassword, changing the parameters for your case.
  • See the build_image.sh file for details on the parameter values

Development

Directories

• internal/base: base station operation
• internal/drone: drone operation
• internal/gpio: Raspberry Pi GPIO pin interface
• internal/input: Input sensor interfaces
• internal/output: Output interfaces
• internal/control: Control algorithms compiled to shared libraries
• internal/protocol: Communication protocol for base and drone

General development flow

• A user defined control algorithm is created here: internal/control/some_name/main.go
• Your algorithm needs to satisfy the following interfaces:
  • Have a Main function with the following signature: Main(c *config.Config, priority int, eCh *chan sensor.Event, pq *output.Queue)

Your algorithm fundamentally needs to do these things:

• Utilize input interfaces in internal/input to determine what actions need to be taken.
• Translate into actions that utilize output interfaces in internal/output, if necessary.

If you write more than one control algorithm, such as the default examples of obstacle_avoidance and pilot, you'll need to define their priority using controlAlgorithmPriority in configs/config.yaml.

Logging

droneOS logs in a very specific format to allow the base station to know the whole state of the system. This is useful for debugging the drone offline. Keep in mind that the debug logging only works when the drone is in WiFi range of the base station., in order to save on bandwidth constraints over radio.

Log levels are important, and divide two categories of emitted output:

• Human readable:
  • Error
  • Info
• Machine readable:
  • Debug

Logs can be filtered with jq:

./droneOS.bin | jq '.[] | select(.level == "Debug")'

Raspberry PI GPIO

• 25 GPIO
• 8 ground
• 2 5V
• 2 3.3V
• 2 ID EEPROM

Pin	Name	BCM GPIO	Function
1	3.3V		Power
2	5V		Power
3	GPIO2	GPIO2	SDA1, I²C Data
4	5V		Power
5	GPIO3	GPIO3	SCL1, I²C Clock
6	GND		Ground
7	GPIO4	GPIO4	GPCLK0
8	GPIO14	GPIO14	UART0_TXD
9	GND		Ground
10	GPIO15	GPIO15	UART0_RXD
11	GPIO17	GPIO17	GPIO_GEN0
12	GPIO18	GPIO18	PCM_CLK, PWM0
13	GPIO27	GPIO27	GPIO_GEN2
14	GND		Ground
15	GPIO22	GPIO22	GPIO_GEN3
16	GPIO23	GPIO23	GPIO_GEN4
17	3.3V		Power
18	GPIO24	GPIO24	GPIO_GEN5
19	GPIO10	GPIO10	SPI0_MOSI
20	GND		Ground
21	GPIO9	GPIO9	SPI0_MISO
22	GPIO25	GPIO25	GPIO_GEN6
23	GPIO11	GPIO11	SPI0_SCLK
24	GPIO8	GPIO8	SPI0_CE0_N
25	GND		Ground
26	GPIO7	GPIO7	SPI0_CE1_N
27	ID_SD	GPIO0	I²C ID EEPROM Data (ID_SD)
28	ID_SC	GPIO1	I²C ID EEPROM Clock (ID_SC)
29	GPIO5	GPIO5	GPIO_GEN1
30	GND		Ground
31	GPIO6	GPIO6	GPIO_GEN2
32	GPIO12	GPIO12	PWM0
33	GPIO13	GPIO13	PWM1
34	GND		Ground
35	GPIO19	GPIO19	PCM_FS, PWM1
36	GPIO16	GPIO16	GPIO_GEN4
37	GPIO26	GPIO26	GPIO_GEN7
38	GPIO20	GPIO20	PCM_DIN
39	GND		Ground
40	GPIO21	GPIO21	PCM_DOUT

Other detail

• Power Pins: Pins 1 (3.3V), 2 (5V), 4 (5V), and 17 (3.3V) are power supply pins.
• Ground Pins: Pins 6, 9, 14, 20, 25, 30, 34, and 39 are ground pins.
• GPIO Pins: The GPIO (General Purpose Input/Output) pins can be programmed for various functions.
• Special Function Pins: Some GPIO pins have special functions like I²C, SPI, UART, and PWM.

Notes

• Currently, we're patching the kernel during compilation from source. Once the mainline kernel has the realtime patch, we can remove the kernel source patch and compilation:
  • https://wiki.linuxfoundation.org/realtime/start

Resources

• Raspberry PI
  • https://www.raspberrypi.com/documentation/computers/linux_kernel.html
    • https://cdn.kernel.org/pub/linux/kernel/projects/rt/6.6/
  • https://www.raspberrypi.com/documentation/computers/raspberry-pi.html#raspberry-pi-zero-2-w
  • https://www.raspberrypi.com/documentation/computers/raspberry-pi.html#gpio-and-the-40-pin-header
• Go libraries
  • https://github.com/warthog618/go-gpiocdev
  • https://gobot.io/documentation/drivers
  • https://github.com/tinygo-org/drivers/tree/release/sx126x
  • https://github.com/thinkski/go-v4l2

Contributing

Feel free to fork the PR and add plugins for your project.