mbed os sd block decive

main.cpp

#include "mbed.h"
#include "SDBlockDevice.h"


SDBlockDevice sd(MBED_CONF_SD_SPI_MOSI, MBED_CONF_SD_SPI_MISO, MBED_CONF_SD_SPI_CLK, MBED_CONF_SD_SPI_CS);
uint8_t block[512] = "Hello World!\n";

using namespace std::chrono;
Timer t;

int main()
{
    printf("\nRESTART delayer\n");

// Call the SDBlockDevice instance initialisation method
    if (0 != sd.init()) {
        printf("Init failed \n");
        return -1;
    }
    printf("sd size: %llu\n",         sd.size());
    printf("sd read size: %llu\n",    sd.get_read_size());
    printf("sd program size: %llu\n", sd.get_program_size());
    printf("sd erase size: %llu\n",   sd.get_erase_size());

// Set the frequency
    if (0 != sd.frequency(50000000)) {
        printf("Error setting frequency \n");
    }

  // single block writes/reads ~2-5millisec, ie estimated "safe bound" for write and read ~10millisec
  // 48 kHz sampling rate
  // 12 bit sample quantization
  // -> 1.5 * 48000 = 72000 Byte  to read+write per second
  // 72000 / 512 * 10 ms = 1406.25ms required --> too slow
  // in principle with 8bit samples this should work..
  // consider using a board with SDIO support (like the stm32 l1/4xx) which should? have a higher throughput (even enough for stereo? ;)
  
    for (int i = 0; i < 10; i++){

        if (0 != sd.erase(i*128, sd.get_erase_size())) {
            printf("Error Erasing block \n");
        }

        t.reset();
        t.start();
        // Write data block to the device
        if (0 == sd.program(block, i*512, 512)) {
        // if (0 == sd.read(block, 0, 512)) {
            // Read the data block from the device
            if (0 == sd.read(block, i*512, 512)) {
            //     // Print the contents of the block
                // printf("%s", block);
            }
        }
        t.stop();

        printf("i: %llu ms\n", duration_cast<milliseconds>(t.elapsed_time()).count());



    }

    // Call the SDBlockDevice instance de-initialisation method
    sd.deinit();
}

mbed_app.json

{
    "target_overrides": {
        "*": {
            "platform.stdio-convert-newlines": true,
            "target.features_add": ["STORAGE"],
            "target.components_add": ["SD"]
        },
        "NUCLEO_F303K8": {
            "sd.SPI_MOSI": "SPI_MOSI",
            "sd.SPI_MISO": "SPI_MISO",
            "sd.SPI_CLK":  "SPI_SCK",
            "sd.SPI_CS":   "SPI_CS"
        }
    }
}