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Questions tagged [eeprom]

Electronically Erasable ROM is a type of memory available on most boards. It is used for storing persistent data. Use the tag for questions about the EEPROM library or the hardware.

198 questions
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Is using malloc() and free() a really bad idea on Arduino?

The use of malloc() and free() seems pretty rare in the Arduino world. It is used in pure AVR C much more often, but still with caution. Is it a really bad idea to use malloc() and free() with Arduino?
Cybergibbons
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What is the real lifetime of EEPROM?

ATMEL says the cell lifetime of an EEPROM cell is about 100,000 write cycle/ cell. Is this actually how the EEPROM performs in the wild? If I do not change the value of a cell, does this stress the lifetime? For example, if I write the value 0xFF to…
Marlon Abeykoon
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How to read and write EEPROM in ESP8266

I need to know how I can write integer values in EEPROM and retain the value on power on. char *Red = strstr(myTestUrl, "/R"); if (Red) { int RedValue = atoi(Red + 2); analogWrite(12, RedValue); Serial.println("Red :"); …
MICRO
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How to remember variable values after rebooting an Arduino Uno R3 board?

Is there any way to store the values of necessary variables somewhere (may be in a file that gets updated by the program at various events), which can be read back when program starts after rebooting the Arduino board? I am trying to control my AC…
Samik Chattopadhyay
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Is it possible to run a binary from EEPROM?

Say I wrote a compiled sketch to EEPROM then read it. Could I run the program from EEPROM? I guess the question is: Can an Arduino run software not in flash memory in the middle of executing the software in flash?
Piper McCorkle
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How is stack memory used for fuctions and local variables?

I wanted to save some values to the EEPROM and also wanted to free up SRAM by avoiding some variable declarations, but EEPROM memory is byte wise. If I want to store an int value, I have to use some expressions repeatedly. I thought I would make…
Nafis Abdullah Khan
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How to increase life of EEPROM?

I want to store a few (8 as of now) IR codes into my Board's EEPROM. It would be great if someone could suggest a few tips to maximize the lifetime. The IR codes in my sketch are saved in array of unsigned longs. I know that the count of times that…
karx
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Can you access the EEPROM of an ATtiny with Arduino Code?

I'm attempting to reduce the amount of RAM being used by my program by writing some values to the EEPROM of my micro controller. I'm currently programming on the ATtiny85 which has 512 Bytes of EEPROM. According to the documentation this is how you…
Isabel Alphonse
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EEPROM endurance and page size

I would like to estimate the effective (minimum) endurance of the EEPROM of the Arduino in terms of single-byte writes. The datasheet of the ATmega used on many Arduino boards says (page 20): The ATmega48A/PA/88A/PA/168A/PA/328/P contains…
fuenfundachtzig
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Arduino digitalWrite 1 or 0 instead of HIGH or LOW

Is it ok to use digitalWrite(pin, 1) instead of digitalWrite(pin, HIGH) or digitalWrite(pin, 0) instead of digitalWrite(pin, LOW) I want it that way to make the coding lesser because I save values on EEPROM with 1's and 0's. So if I want to use…
Sam San
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Can I improve EEPROM lifetime by not changing bits?

In my current project I need to store the current elapsed time in hours to retrieve it in case of power loss. Since I am using a Arduino Nano I would ideally like to use the built in EEPROM without additional hardware. The written values and their…
maxmilgram
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Run code once after programming

I'm using EEPROM to store project settings non-volatile. After reuploading the sketch to my board (over SPI via ArduinoISP), the EEPROM is reset to full 0xFFs and I have to manually do a "software reset" with a second switch, which initializes the…
towe
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Using Arduino as Keylogger

Is it possible to use arduino uno r3 as USB keylogger by connecting the usb male pin to CPU and keybord cable to female USB pin of arduino. So that the keystrokes are stored in EEPROM. Without using an external storage modules or other components? I…
Ganesh
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Set EEPROM from PC before program

I have been working on an arduino program, which has gotten rather large. I am close to hitting the 32k limit on Flash for my ATmega328p. I would like lower my program size by saving some of my many string literals into EEPROM. All of the example…
riverrun
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EEPROM value reverting to 255

When I write '13' to the EEPROM and read it straight after it works correctly. However when I comment out the write part of the code and try to just read the data, the value is no longer 13 as it used to be but reverts back to 255. Whats going on? I…
MoKaM
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