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PlatformIO Setup

OpenSkyhawk firmware builds with PlatformIO. Each board is its own project. Start from the templates in Firmware/Templates/ — not from an existing panel's platformio.ini, which may carry stale dependencies.

Start from a template

Firmware/Templates/ has a ready project per tier: PanelGroup/, PanelBridge/, and SimGateway/. Copy the one you need into place (a PanelGroup goes under Firmware/Panels/<YourPanel>/) and edit its platformio.ini.

A PanelGroup platformio.ini, annotated

[env:PanelGroup]
platform = ststm32
board = genericSTM32F103C8        ; STM32F103C8 for nodes (see board note below)
framework = arduino
board_build.f_cpu = 72000000L

build_flags =
    -DNODE_ID=1                   ; unique per board, 1–63 — set this!
    -DHAL_CAN_MODULE_ENABLED      ; enable the bxCAN peripheral
    -DUSB_NONE                    ; inert — USB is off because USBCON is never defined
    -DHSE_VALUE=8000000           ; external 8 MHz crystal, required for CAN timing

lib_extra_dirs = ${PROJECT_DIR}/../../Libraries
lib_ldf_mode = deep+              ; needed so Adafruit BusIO finds framework headers
lib_deps =
    HIDControls
    STM32Board
    PanelGroup
    CANProtocol
    A4EC
    blemasle/MCP23017@^2.0.0
    adafruit/Adafruit ADS1X15@^2.0.0

upload_protocol = stlink
monitor_speed = 115200

The two build flags people forget: -DNODE_ID (every board needs a unique value — see NODE_ID & CAN Addressing) and -DHSE_VALUE=8000000 (declares the 8 MHz crystal frequency to HAL — needed for correct CAN timing, since the internal RC oscillator isn't accurate enough for 500 kbps CAN). Note -DHSE_VALUE does not by itself select HSE; STM32Board's SystemClock_Config does that (see Design Decisions).

-DUSB_NONE is a label, not a switch — nothing in STM32duino or PlatformIO reads it. USB really is off, and CAN really does own PA11/PA12 (they're the F103's USB D+/D− pins), but what keeps USB off is that USBCON is never defined. Leave the flag in place as documentation of the decision.

For every flag in this file — plus the ones that aren't, their defaults, and where each is read — see Build Flags.

Which STM32 variant

Per the variant policy, all STM32 boards default to genericSTM32F103C8 (64 KB) — both PanelGroup nodes and PanelBridge. PanelBridge carries the full DCS-BIOS input map yet still compiles to ~26 KB flash, so it fits the C8 comfortably. genericSTM32F103CB (128 KB) is a drop-in fallback (identical LQFP48 footprint) for any future build that ever exceeds 64 KB — no board currently needs it. Note: the in-tree Templates/PanelGroup should target genericSTM32F103C8.

Flashing

STM32 boards flash over SWD with an ST-Link (upload_protocol = stlink). PlatformIO drives the probe directly — pio run -t upload. SimGateway (RP2040) flashes over USB by UF2 or straight from PlatformIO; no ST-Link.

Blue Pill clone won't connect? Override the tap ID

Many clones report a non-standard JTAG ID and ST-Link refuses to connect with "tap not found." Uncomment the override in the template:

ini upload_flags = -c set CPUTAPID 0x2ba01477

The standard ID is 0x1ba01477; the common clone is 0x2ba01477.

Serial monitor

monitor_speed = 115200 matches the DiagSerial debug stream (USART1, PA9/PA10). Attach a USB-to-TTL adapter to the board's 3-pin debug header and pio device monitor. See Debugging on STM32.