ESP-IDF m95 EEPROM Library

This is a simple EEPROM library for the m950x0 and m95mx0 series SPI EEPROM chips. For example: m95m01 chip. This library targets the ESP-IDF framework.

This is a C and C++ library available via m95_eeprom.h and m95_eeprom.hpp respectively.

This code was tested on the m95m04 chip with the ESP32-S3-WROOM-1 microcontroller using SPI2 and SPI3 buses. Implemented based on the documentation provided in the m95m04-dr-5 datasheet.

A PlatformIO library.json is provided. You can add this library as git clone (or as a git submodule) into your own project's lib folder. PlatformIO registry link.

Available commands

• Enable write (WEL bit)
• Disable write (WEL bit)
• Read status register
• Wait for write to finish (WIP bit)
• Read one byte
• Write one byte
• Read a range of bytes
• Write a range of bytes

Not available

• Write status register
• Identification pages
• Locking

Usage

#include <m95_eeprom.h>

void app_main() {
    spi_bus_config_t bus = {};
    bus.data0_io_num = -1;
    bus.data1_io_num = -1;
    bus.data2_io_num = -1;
    bus.data3_io_num = -1;
    bus.data4_io_num = -1;
    bus.data5_io_num = -1;
    bus.data6_io_num = -1;
    bus.data7_io_num = -1;
    bus.miso_io_num = SPI3_PIN_MISO;
    bus.mosi_io_num = SPI3_PIN_MOSI;
    bus.sclk_io_num = SPI3_PIN_CLK;
    bus.quadhd_io_num = -1;
    bus.quadwp_io_num = -1;
    bus.max_transfer_sz = 4;

    // Initialize SPI host bus
    esp_err_t ret = spi_bus_initialize(SPI3_HOST, &bus, SPI_DMA_CH_AUTO);
    ESP_ERROR_CHECK(ret);

    // Init EEPROM device & initializes SPI device
    // Uses 24 bit addressing (check your datasheet!)
    // Tested on m95m04
    m95_eeprom_config_t config = {};
    config.host = SPI3_HOST;
    config.cs_pin = EEPROM_CS_PIN;
    config.address_size = 24;

    // Do the init with the config
    m95_eeprom_handle_t eeprom;
    ret = m95_eeprom_init(config, &eeprom);
    ESP_ERROR_CHECK(ret);

    // Enable write.
    // !!! MUST BE DONE BEFORE EACH WRITE COMMAND !!!
    ret = m95_eeprom_enable_write(eeprom);
    ESP_ERROR_CHECK(ret);

    // Write length of 12 bytes at an address 0x05
    ret = m95_eeprom_write_range(eeprom, 0x05, "Hello World!", 12);
    ESP_ERROR_CHECK(ret);

    // Wait for the read to finish
    ret = m95_eeprom_enable_wait(eeprom);
    ESP_ERROR_CHECK(ret);

    // Read destination
    char buffer[13];
    buffer[12] = '\0'; // Null terminate string
    memset(buffer, 'x', 12); // Optional, for debugging purposes

    // Read length of 12 bytes from an address 0x05
    ret = m95_eeprom_read_range(eeprom, 0x05, buffer, 12);
    ESP_ERROR_CHECK(ret);

    printf("EEPROM read at address 0x05 result: %s\n", buffer);

    // Deinitialize & remove SPI device from the SPI host bus
    // Additinally frees the memory allocated by the init function.
    ret = m95_eeprom_deinit(eeprom);
    ESP_ERROR_CHECK(ret);
}