42 lines
1.9 KiB
Markdown
42 lines
1.9 KiB
Markdown
# Simple Example of FreeRTOS porting on a Custom nRF52 Board
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By default, the nRF52 chip is not supported by FreeRTOS. However, since it uses an ARM Cortex-M4, we can manually port FreeRTOS to it.
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This repository provides basic examples of porting FreeRTOS to the nRF52 using PlatformIO with the Arduino framework. The FreeRTOS kernel files are located in `lib/FreeRTOS/`, so we need to add the following build flags and sources to `platformio.ini`:
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```ini
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build_flags =
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-I lib/FreeRTOS/include
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-I lib/FreeRTOS/portable/GCC/ARM_CM4F
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build_src_filter =
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+<*>
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+<lib/FreeRTOS/*.c>
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+<lib/FreeRTOS/portable/GCC/ARM_CM4F/*.c>
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+<lib/FreeRTOS/portable/MemMang/*.c>
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```
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The FreeRTOS kernel used in this example is version 11.0.0.
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## Examples
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- ### Simple FreeRTOS for LED Blinking with Two LEDs
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This example modifies `FreeRTOSConfig.h` to add the following handlers, which connect the MCU to FreeRTOS:
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- `#define vPortSVCHandler SVC_Handler`
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- `#define xPortPendSVHandler PendSV_Handler`
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- `#define xPortSysTickHandler SysTick_Handler`
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The SysTick timer uses the CPU's main clock.
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- ### Simple FreeRTOS with Low-Power Mode and LED Blinking
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In this example, `FreeRTOSConfig.h` is modified to add:
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- `#define vPortSVCHandler SVC_Handler`
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- `#define xPortPendSVHandler PendSV_Handler`
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The SysTick timer uses the RTC's clock, set with `#define configSYSTICK_CLOCK_HZ (32768UL)`. Additionally, the default SysTick behavior of the RTOS is overridden in `low_power_config.cpp`.
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**Figure:** Power consumption measurement shows ~2.5 µA at 3V when the LED is off.
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**Note: In this example, I am using a custom board based on nRF52832. Also, for the programmer, CMSIS-DAP programmer hardware is used (with 4 connections: VCC, GND, DIO, CLK). Adjust its upload_protocol and debug_tool according to your needs.* |