flash_at25.h

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/*
 * flash12.h
 * module for reading and writing to FLASH12 click - chip AT25EU0041A (4Mbit / 512KB)
 * gemini: https://gemini.google.com/share/fee2e604904f
 *  Created on: 24. 12. 2025
 *      Author: Milan
 *
 * Module handles writing without regard to 256bytes boundary
 * Flash is activated via CS to GND. Consumption is 2mA
 * StandBy mode is CS to VCC, consumption 14mcA
 */
 
#ifndef INC_FLASH12_H_
#define INC_FLASH12_H_
 
/*
 * MT 24.12.2025
 */
 
#include "stm32wlxx_hal.h"
 
// Device Info for AT25EU0041A
#define AT25_MANUFACTURER_ID 0x1F
#define AT25_MEMSIZE (1<<19)    // 512kB alias 4Mb
 
#pragma pack(1)
/**
 * @brief Configuration and state descriptor for one AT25EU0041A flash chip.
 *        Pass a pointer to this struct to every flash_at25_XXX function.
 *        Populate the IN fields before calling flash_at25_Init(); the OUT
 *        fields are filled by the initialisation routine.
 */
typedef struct
{
    SPI_HandleTypeDef *Spi; /**< IN  SPI handle used to communicate with the chip */
    GPIO_TypeDef* CSPort;   /**< IN  GPIO port of the chip-select (CS/NSS) pin */
    uint16_t CSPin;         /**< IN  GPIO pin number of the chip-select line */
    int8_t Is;              /**< OUT Set to 1 by flash_at25_Init() if the chip was identified, 0 otherwise */
    uint32_t Size : 24;     /**< OUT Total usable memory in bytes (e.g. 524288 for the 4 Mbit / 512 KB variant) */
} flash_at25CS_t;
#pragma pack()
 
/**
 * @brief - check if flash chip is present or not
 * @param tryInit - in case sensor is not yet initialized, 1 - attempt to initialize again, 0 - no
 */
int8_t flash_at25_Is(flash_at25CS_t *s, int8_t tryInit);
 
/**
 * @brief Initialization for AT25EU0041A flash chip
 * Performs proper device identification and verification
 * Suitable for frequent operations with improved error checking
 * @param s Pointer to flash configuration structure
 * @retval HAL_OK if device identified correctly, HAL_ERROR otherwise
 */
HAL_StatusTypeDef flash_at25_Init(flash_at25CS_t *s);
 
/**
 * @brief Fast read from flash memory
 * Uses fast read command (0x0B) for improved performance in frequent read operations
 * Includes boundary checking and ready state verification
 * @param s Pointer to flash configuration structure
 * @param addr Starting address to read from (24-bit address, 0x000000 to 0x07FFFF for 512KB)
 * @param buffer Pointer to destination buffer
 * @param size Number of bytes to read
 * @retval HAL_OK on success, HAL_ERROR on failure, HAL_TIMEOUT on timeout
 */
HAL_StatusTypeDef flash_at25_Read(const flash_at25CS_t *s, uint32_t addr, void *buffer, uint16_t size);
 
/**
 * @brief Write to flash memory with sector preservation
 * Handles page-aligned writes efficiently with proper verification
 * Preserves existing data in flash sectors by reading, modifying, and writing back
 * 
 * This function implements a read-modify-write approach:
 * 1. Calculates which 256 Page needs to be erased based on addr & size
 * 2. For each affected Page: reads it, resets bytes to 0xFF where new data will be written
 * 3. Erases the sector and writes back the modified sector data
 * 4. Then writes the new data to the prepared sectors
 * 
 * Handles sector boundaries automatically - if data crosses sector boundary, both sectors are processed
 * 
 * Includes boundary checking, write enable verification, and proper timeout handling
 * @param s Pointer to flash configuration structure
 * @param addr Starting address to write to (24-bit address, 0x000000 to 0x07FFFF for 512KB)
 * @param data Pointer to source data buffer
 * @param size Number of bytes to write
 * @retval HAL_OK on success, HAL_ERROR on failure, HAL_TIMEOUT on timeout
 */
HAL_StatusTypeDef flash_at25_Write(const flash_at25CS_t *s, uint32_t addr, const void *data, uint16_t size);
 
 
#endif /* INC_FLASH12_H_ */