This project demonstrates the use of a circular buffer on the Raspberry Pi Pico's onboard flash memory. A circular buffer is a data structure that cyclically uses a fixed-size array to store data. Data is added sequentially, and the oldest data is overwritten by the newest entries. This structure is particularly useful for resource-constrained microcontrollers to maintain sensor data over a period. The implementation persists data in flash memory, making it resilient to power disruptions. Additionally, it features APIs to traverse the data in both ascending and descending order.
The demonstration will continue to record temperature sensor data with elapsed time.
This circular buffer is designed for flash memory and includes a built-in gap. The gap maintains a constant unused area between the buffer's start and end, set to at least the size of the flash memory's erase unit (sector size). This design minimizes erase cycles and wear on memory cells, thereby extending the lifespan of the flash memory.
This structure is particularly effective for storing log data in IoT devices. Users only need to specify the size and number of entries; the buffer automatically calculates the gap size to optimize flash memory usage.
git submodule update --init
cd lib/pico-sdk; git submodule update --init; cd ../../
mkdir build; cd build
cmake ..
makeOnce built, the circularbuffer.uf2 file can be dragged and dropped onto your Raspberry Pi Pico to install and run the example.
The tests directory contains code to verify the API's behavior. After building and installing the test code on the Pico, the unit tests are executed directly on the device, and results are sent via UART.
make tests
To run the tests, transfer the tests/tests.uf2 file to your Pico. For a more comprehensive debugging experience, connect the Raspberry Pi Debug Probe to the SWD Debug and UART Serial interfaces of the Pico. Use the following command to install and run the tests:
make run_tests