nRF52 Runtimes

Important

nrf52-runtimes has moved to community-bb-runtimes.

This repository generates Ada/SPARK runtimes for the following SoCs in the nRF52 series:

• nRF52832
• nRF52833
• nRF52840

The following runtime profiles are supported for each of the above:

• light
• light-tasking
• embedded

Usage

Using the light_tasking_nrf52840 as an example, first edit your alire.toml file and add the following elements:

• Add light_tasking_nrf52840 in the dependency list:

  [[depends-on]]
  light_tasking_nrf52840 = "*"

Then edit your project file to add the following elements, depending on your chosen runtime profile:

• when using the light runtime profile:
  • "with" the run-time project file:

    with "runtime_build.gpr";

  • specify the Target and Runtime attributes:

    for Target use runtime_build'Target;
    for Runtime ("Ada") use runtime_build'Runtime ("Ada");

• when using the light-tasking or embedded runtime profile:
  • "with" the run-time project file:

    with "ravenscar_build.gpr";

  • specify the Target and Runtime attributes:

    for Target use ravenscar_build'Target;
    for Runtime ("Ada") use ravenscar_build'Runtime ("Ada");

Resources Used

The light-tasking and embedded runtime profiles use an RTC peripheral to implement Ada semantics for time, i.e., delay statements and the package Ada.Real_Time. The RTC interrupt runs at the highest priority. The RTC runs from the low frequency clock (LFCLK) which runs at 32.768 kHz. The LFCLK source is configured via the crate configuration, and may be either the external 32 kHz crystal oscillator (LFXO), the internal 32 kHz oscillator (LFRC), or synthesized from the 16 MHz high-speed clock (HFCLK).

Runtime Configuration

Crate Configuration

The runtime is configurable through the following crate configuration variables:

Variable	Values	Default	Description
Time_Base	"RTC0" "RTC1" "RTC2"	"RTC2"	Selects which RTC peripheral the runtime uses to implement the semantics of `Ada.Real_Time`.
LFCLK_Src	"Xtal" "RC" "Synth"	"Xtal"	Sets the clock source for the low frequency clock (LFCLK). "Xtal" selects the external 32 kHz crystal as the LFCLK source (LFXO) "RC" selects the internal LFRC oscillator as the LFCLK source "Synth" synthesises the LFCLK from the HFCLK
Use_SWO_Trace	true false	true	When true, the SWO pins are configured during startup to enable SWO trace.
Use_Reset_Pin	true false	true	When true, P0.18 is configured as the reset pin.

For example, to configure the light-tasking-nrf52840 runtime to use the internal LFRC oscillator as the LFCLK source and RTC0 for timing, add this to your alire.toml:

[configuration.values]
light_tasking_nrf52840.LFCLK_Src = "RC"
light_tasking_nrf52840.Time_Base = "RTC0"

GPR Scenario Variables

The runtime project files expose *_BUILD and and *_LIBRARY_TYPE GPR scenario variables to configure the build mode (e.g. debug/production) and library type. These variables are prefixed with the name of the runtime in upper case. For example, for the light-tasking-nrf52832 runtime the variables are LIGHT_TASKING_NRF52832_BUILD and LIGHT_TASKING_NRF52832_LIBRARY_TYPE respectively.

The *_BUILD variable can be set to the following values:

• Production (default) builds the runtime with optimization enabled and with all run-time checks suppressed.
• Debug disables optimization and adds debug symbols.
• Assert enables assertions.
• Gnatcov disables optimization and enables flags to help coverage.

The *_LIBRARY_TYPE variable can be set to either static (default) or dynamic, though only static libraries are supported on this target.

You can usually leave these set to their defaults, but if you want to set them explicitly then you can set them either by passing them on the command line when building your project with Alire:

alr build -- -XLIGHT_TASKING_NRF52840_BUILD=Debug

or by setting them in your project's alire.toml:

[gpr-set-externals]
LIGHT_TASKING_NRF52840_BUILD = "Debug"