Frame 1.0

First public release, CNC-milled in 1.5 mm carbon fibre and flown. Snap-on landing gear through a 1.65 mm flex slit, openings of plate thickness + 0.2 mm with R0.75 corners, 2.2 x 12 mm battery-strap slots, and a 30.5 mm M2 flight-controller hole pattern.

Files: hardware/frame/. DXF for CNC milling, its drawing and a 3D render. Licence: CC BY-NC-SA 4.0, adapted from LiteWing by Circuit Digest.

Firmware 1.0.0

First public release, for flight controller 1.0, flown with the SparrowFlight iOS app.

• Angle mode at 500 Hz, rate PID and X mixer with roll/pitch priority.
• ToF altitude hold with an accelerometer-aided height estimate; the hold follows the surface below.
• Velocity mode with button take-off and landing; thrust mode as in ESP-Drone, and thrust mode alone on a board without a ToF.
• Auto-landing on stick release or link loss, with app steering on the way down; safety stops on tilt, crash and lost ToF; take-off refused without an IMU.
• Motor trim measured at the first battery boot and with trim measure, kept in flash; per-unit calibration in flash; blackbox log of the last 15 s of each flight.
• Camera video from the camera expansion board of a XIAO ESP32-S3 Sense, fitted to the Plus or on a whole Sense, over UDP port 81, at most 15 frames a second, captured only while the app is watching.
• WiFi access point SPARROW_<MAC> on channel 6, with DHCP that offers no gateway, so a phone stays on it and keeps mobile data for the internet. DHCP replies go to the phone's own WiFi address, not broadcast, so a phone that dozes just after joining still gets them.
• Telemetry and replies to up to 3 devices, sent by a task on core 0 so the control loop does not wait for the network.
• Bluetooth advertising on the ground so the app can list nearby drones; it stops while an app is linked.
• Commands get, hw (which sensors the board has) and params (each parameter's range, default and storage).
• Eleven parameters: stick feel, take-off and hold heights, hover thrust and camera resolution are saved in flash and change only on the ground; the roll and pitch offsets are stored with trim save. The rate gains, the WiFi channel, the ToF ranging profile and the camera frame rate are fixed, and the motor trim is measured, not set.

Files: firmware/. PlatformIO source for the XIAO ESP32-S3 Plus; build and flash it as described in the firmware README. No prebuilt binaries. Licence: GPL-3.0-or-later.

Flight controller 1.0

First public release, made by JLCPCB (2 layers, Economic PCBA), assembled and flown. XIAO ESP32-S3 Plus on two 7-pin rows, GY-521 MPU-6050 soldered flat on the bottom, GY-530 VL53L0X on the top, TPS63020 buck-boost, SW1 slide switch on the regulator enable with an indicator LED, four low-side brushed-motor drivers.

The boards flown so far were made from the same copper, drill and solder-mask data. Only the silkscreen artwork differs: the published files carry the Sparrow logo on the top, between the GY-530 and the XIAO, the version marking "v1.0" on the top at the edge opposite SW1, and the "sparrow" wordmark on the bottom.

Known issues:

• The IMU and ToF lose I2C readings when the XIAO sits in a socket and moves. Solder the XIAO directly into the board.
• Standard JST PH connectors are rated for about 2 A, while four motors at full throttle draw several amps. Check the battery lead for voltage drop and heat.

Files: hardware/flight-controller/. EasyEDA Pro project, schematic PDF, Gerber, BOM and pick-and-place files for JLCPCB. Licence: CERN-OHL-S-2.0.