Example of pico_filesystem library for pico-sdk.

This project is a demonstration codes of the pico_filesystem library, which was added independently to pico-sdk 1.5 develop branch. The library adds a POSIX file API compliant file manipulation API that allows access to Pico's on-board flash memory and SD card. The project requires a forked pico-sdk. Check it out and specify it in PICO_SDK_PATH:

Pull requests to pico-sdk are as follows: raspberrypi/pico-sdk#1715

Examples

App	Description
hello_world	File writing and reading
auto_init	Transparently perform file system initialisation.
ram_disk	RAM disk with Heap block device.
benchmark	Data transfer tests with different block devices and different file system combinations.
unittest	Unit tests
usb_msc_logger	Data logger that mounts littlefs and FAT on flash memory and shares it with a PC via USB mass storage class.
custom_blockdevice	Add your own block devices. Useful for debugging file systems.

How to build forked pico-sdk

git clone --branch filesystem_support https://github.com/oyama/pico-sdk.git
cd pico-sdk
git submodule update --init

Build samples

Go to the directory of each sample code:

mkdir build; cd build
PICO_SDK_PATH=/path/to/forked/pico-sdk cmake ..
make

If no SD card device is connected, the WITHOUT_BLOCKDEVICE_SD option can be specified to skip the SD card manipulation procedure from the examples:

PICO_SDK_PATH=/path/to/forked/pico-sdk cmake .. -DWITHOUT_BLOCKDEVICE_SD=YES

Running examples of using SD cards

If an SD card is to be used, a separate circuit must be connected via SPI. As an example, the schematic using the Adafruit MicroSD card breakout board+ is as follows

The spi and pin used in the block device argument can be customised. The following pins are used in the demonstration.

Pin	PCB pin	Usage	description
GP18	24	SPI0 SCK	SPI clock
GP19	25	SPI0 TX	SPI Master Out Slave In
GP16	21	SPI0 RX	SPI Master In Slave Out
GP17	22	SPI0 CSn	SPI Chip select

More details

The pico_filesystem library is based on the pico-vfs library. See the pico-vfs repository for more information on the available APIs, file systems, etc.