Arduino 中 EEprom 寫入讀取清除

轉自：https://www.arduino.cn/thread-1157-1-1.html

EEPROM (Electrically Erasable Programmable Read-Only Memory)，電可擦可編程只讀存儲器--一種掉電后數據不丟失的存儲芯片。 簡而言之就是你想斷電后arduino還要保存一些參數，就使用EEPROM吧。 在各型號的arduino控制器上的AVR芯片均帶有EEPROM，也有外接的EEPROM芯片，常見arduino控制器的EEPROM大小： Arduino UNO、Arduino duemilanove-m328、Zduino m328均使用ATmega328芯片，EEPROM都為1K Arduino duemilanove-m168的EEPROM為512bytes Arduino 2560的EEPROM為4K
下面我們介紹arduino自帶的EEPROM使用方法，arduino的庫已經為我們准備好了EEPROM類庫，我們要使用得先調用EEPROM.h，然后使用write和read方法，即可操作EEPROM。 另：下面的官方例子由於寫成較早，所以講EEPROM的大小都定為了512字節，實際使用中，大家可參照上面所說的EEPROM大小，自行更改。
1.寫入 選擇 File>Examples>EEPROM>eeprom_write

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	/*
	* EEPROM Write
	*
	* Stores values read from analog input 0 into the EEPROM.
	* These values will stay in the EEPROM when the board is
	* turned off and may be retrieved later by another sketch.
	*/
	#include <EEPROM.h>
	// EEPROM 的當前地址,即你將要寫入的地址,這里就是從0開始寫
	int addr = 0;
	void setup()
	{
	}
	void loop()
	{
	//模擬值讀出后是一個0-1024的值，但每字節的大小為0-255，所以這里將值除以4再存儲到val
	int val = analogRead(0) / 4;
	// write the value to the appropriate byte of the EEPROM.
	// these values will remain there when the board is
	// turned off.
	EEPROM.write(addr, val);
	// advance to the next address.  there are 512 bytes in
	// the EEPROM, so go back to 0 when we hit 512.
	addr = addr + 1;
	if (addr == 512)
	addr = 0;
	delay( 100);
	}

2.讀取 選擇 File>Examples>EEPROM>eeprom_read

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	/*
	* EEPROM Read
	*
	* Reads the value of each byte of the EEPROM and prints it
	* to the computer.
	* This example code is in the public domain.
	*/
	#include <EEPROM.h>
	// start reading from the first byte (address 0) of the EEPROM
	int address = 0;
	byte value;
	void setup()
	{
	// initialize serial and wait for port to open:
	Serial.begin( 9600);
	while (!Serial) {
	; // wait for serial port to connect. Needed for Leonardo only
	}
	}
	void loop()
	{
	// read a byte from the current address of the EEPROM
	value = EEPROM.read(address);
	Serial.print(address);
	Serial.print( "\t");
	Serial.print(value, DEC);
	Serial.println();
	// advance to the next address of the EEPROM
	address = address + 1;
	// there are only 512 bytes of EEPROM, from 0 to 511, so if we're
	// on address 512, wrap around to address 0
	if (address == 512)
	address = 0;
	delay( 500);
	}

3.清除 選擇 File>Examples>EEPROM>eeprom_clear 清除EEPROM的內容，其實就是把EEPROM中每一個字節寫入0，因為只用清一次零，所以整個程序都在setup部分完成。

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	/* * EEPROM Clear
	*
	* Sets all of the bytes of the EEPROM to 0.
	* This example code is in the public domain.
	*/
	#include <EEPROM.h>
	void setup()
	{
	// 讓EEPROM的512字節內容全部清零
	for (int i = 0; i < 512; i++)
	EEPROM.write(i, 0);
	// 清零工作完成后，將L燈點亮，提示EEPROM清零完成
	digitalWrite( 13, HIGH);
	}
	void loop()
	{
	}