PIC18F2520 mplab x xc8 EEPROM

Question

Platform MPLAB X
CPU PIC18F2520
Compiler XC8 v1.38

我们正在将一个项目从旧的 (htc) 编译器迁移到 MPLAB X 平台，但无法访问 EEPROM。

旧的编译器支持 eeprom_read 和 eeprom_write 但 XC8 没有，好吧，有定义它们的定义，但它们是“空的”。 （xc.h 包括 htc.h，其中包括 pic18.h） 在 pic.h 行

#if _EEPROMSIZE > 0 && defined(_PLIB)

不是触发而是对应的#else _EEPROMSIZE 和 _PLIB 似乎都没有定义。

为什么这么老（eeprom_read和eeprom_write） xc8 不支持？

我们应该怎么做才能访问 EEPROM？

我们试图看看 Microchip Code Configure 会做什么， 但是MCC不支持CPU PIC18F2520。

The chip do have 256 byte eeprom according to

http://ww1.microchip.com/downloads/en/DeviceDoc/39631E.pdf

问候

Answer 1

是的，正如您所发现的，Microchip 已在 MPLAB X IDE 中删除了 PIC18 系列微控制器的 EEPROM 读/写功能。它将宏保留为空壳（EEPROM_READ()、eeprom_read() 等），不会引发编译器错误/警告，但实际上不会做任何事情！

pic18.h 建议如果#if _EEPROMSIZE > 0 && defined(_PLIB) 为真，那么将填充宏，但是通过手动添加PLIB 宏定义，编译器会抱怨无法找到plib.h。我找不到合适的地方下载“plib”。

一种选择是恢复为直接寄存器操作以执行 EEPROM 读/写（有关特定 PIC18 微控制器的 EEPROM 寄存器定义，请参见 http://ww1.microchip.com/downloads/en/DeviceDoc/39626e.pdf 的第 75 页）。我编写了以下函数，这些函数将其抽象出来并提供与 Microchip 删除的类似的功能：

//! @brief      Reads a single byte of data from the EEPROM.
//! @param      address     The EEPROM address to write the data to (note that not all
//!                         16-bits of this variable may be supported).
//! @returns    The byte of data read from EEPROM.
//! @warning    This function does not return until read operation is complete.
uint8_t Eeprom_ReadByte(uint16_t address)
{

    // Set address registers
    EEADRH = (uint8_t)(address >> 8);
    EEADR = (uint8_t)address;

    EECON1bits.EEPGD = 0;       // Select EEPROM Data Memory
    EECON1bits.CFGS = 0;        // Access flash/EEPROM NOT config. registers
    EECON1bits.RD = 1;          // Start a read cycle

    // A read should only take one cycle, and then the hardware will clear
    // the RD bit
    while(EECON1bits.RD == 1);

    return EEDATA;              // Return data

}

//! @brief      Writes a single byte of data to the EEPROM.
//! @param      address     The EEPROM address to write the data to (note that not all
//!                         16-bits of this variable may be supported).
//! @param      data        The data to write to EEPROM.
//! @warning    This function does not return until write operation is complete.
void Eeprom_WriteByte(uint16_t address, uint8_t data)
{    
    // Set address registers
    EEADRH = (uint8_t)(address >> 8);
    EEADR = (uint8_t)address;

    EEDATA = data;          // Write data we want to write to SFR
    EECON1bits.EEPGD = 0;   // Select EEPROM data memory
    EECON1bits.CFGS = 0;    // Access flash/EEPROM NOT config. registers
    EECON1bits.WREN = 1;    // Enable writing of EEPROM (this is disabled again after the write completes)

    // The next three lines of code perform the required operations to
    // initiate a EEPROM write
    EECON2 = 0x55;          // Part of required sequence for write to internal EEPROM
    EECON2 = 0xAA;          // Part of required sequence for write to internal EEPROM
    EECON1bits.WR = 1;      // Part of required sequence for write to internal EEPROM

    // Loop until write operation is complete
    while(PIR2bits.EEIF == 0)
    {
        continue;   // Do nothing, are just waiting
    }

    PIR2bits.EEIF = 0;      //Clearing EEIF bit (this MUST be cleared in software after each write)
    EECON1bits.WREN = 0;    // Disable write (for safety, it is re-enabled next time a EEPROM write is performed)
}

Answer 2

使用 MCC 选择内存模块，它将创建具有所有所需功能的 memory.c