STM32F407 Runtimes

This repository generates GNAT bare-metal runtimes for STM32F407 targets.

Supported runtime profiles:

• light
• light-tasking
• embedded

Using a runtime from Alire

Example using light-tasking-stm32f407:

1. Add the crate to your project's alire.toml:

[[depends-on]]
light_tasking_stm32f407 = "*"

2. In your project .gpr, reference and use the runtime project:

with "runtime_build.gpr";

project App is
   for Target use runtime_build'Target;
   for Runtime ("Ada") use runtime_build'Runtime ("Ada");

   package Linker is
      for Switches ("Ada") use Runtime_Build.Linker_Switches;
   end Linker;
end App;

Runtime Clock Configuration (important)

Clock setup is controlled by crate configuration variables in your application's alire.toml.

Default behavior is a 168 MHz SYSCLK from HSI through PLL.

For STM32F407 Discovery (8 MHz HSE crystal), a typical configuration is:

[configuration.values]
# HSE on Discovery board
light_tasking_stm32f407.HSE_Clock_Frequency = 8000000
light_tasking_stm32f407.HSE_Bypass = false

# Use PLL as SYSCLK source
light_tasking_stm32f407.SYSCLK_Src = "PLLCLK"
light_tasking_stm32f407.PLL_Src = "HSE"

# 8 MHz -> (N/M)=336/8 => 336 MHz VCO
light_tasking_stm32f407.PLL_M_Div = 8
light_tasking_stm32f407.PLL_N_Mul = 336

# SYSCLK = VCO / 2 = 168 MHz
light_tasking_stm32f407.PLL_P_Div = "DIV2"

# 48 MHz domain for USB/SDIO/RNG
light_tasking_stm32f407.PLL_Q_Div = 7

# Bus prescalers
light_tasking_stm32f407.AHB_Pre  = "DIV1"
light_tasking_stm32f407.APB1_Pre = "DIV4"
light_tasking_stm32f407.APB2_Pre = "DIV2"

Note about timing accuracy

A timing issue where delay 1.0 behaved like ~4 seconds was caused by an incorrect PLLP register encoding in setup_pll.adb. This repository now uses the correct STM32F4 encoding (00=/2, 01=/4, 10=/6, 11=/8) consistently.

Generation templates

The generated crate metadata and examples are based on:

• templates/alire.toml.in
• templates/stm32f407_runtime_config.ads.in
• stm32f407_src/setup_pll.adb

If you regenerate runtimes, these sources carry the fixed behavior.