picoEEPROM library

Github repo

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Overview

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This project, like many others, has been created out of necessity. While programming PicoCalc I encountered a simple issue, how to save data on Arduino (in this case Pi Pico) so that even after a restart that data will still be there, without using an SD card. The answer is very simple, you should use EEPROM. And that’s what I thought immediately BUT as it turns out Pi Pico only has the built-in EEPROM library which allows you to save 4096 bytes of data by changing the value of each byte. And that’s a problem and that’s how this library was born. I needed a way to save data into EEPROM and the solution was non-existent so I made it myself and shared the solution for everybody to use.

Features

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This library is able to save and read Integers, Strings (with dynamic length defined by user and a static length of 20 characters) and Booleans.

Target device

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This project is targeted ONLY for boards from Arduino-Pico library, this means every board with RP2040 and RP235x chip.

Docs

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Max allowed EEPROM size 4096 bytes, in this documentation each byte is going to be referred to as address because we need to specify at which byte we will save the data.

Initializing library

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At the beginning of your Arduino program you need to initialize this library and create an object e.g.:

#include <picoEEPROM.h>
picoEEPROM picoEEPROM;

Functions

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begin(eeprom_size)

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begin function takes one argument - size of eeprom, max allowed size is 4096. begin function returns 0 if everything worked and 1 if eeprom size is invalid. E.g.

picoEEPROM.begin(4096); //begin eeprom with it's max allowed size

putEmptyByte(address)

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putEmptyByte puts one empty byte at a specified address

picoEEPROM.putEmptyByte(0);

putEmptyBytes(num_of_bytes, address)

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putEmptyBytes takes two arguments, number of empty bytes and starting address. It puts a specified number of empty bytes starting at a given address.

picoEEPROM.putEmptyBytes(7, 1);

putInt(value, address)

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putInt takes two arguments, integer value and EEPROM address. Important! This function takes 4 bytes/4 EEPROM addresses to store one integer starting at a given address. putInt returns 1 if value is out of range, 2 if commiting to eeprom failed and 0 if everything worked.

picoEEPROM.putInt(555, 0); //puts int = 555 starting at address 0

getInt(address)

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getInt() takes one argument, EEPROM address (the same address as in putInt). This function returns int read from EEPROM. If something is wrong with retrieved int check if the correct address is specified.

int valueRead = picoEEPROM.getInt(0); //reads int from address 0

putBool(value, bit, address)

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putBool takes three arguments, boolean value, bit at which value will be stored and EEPROM address. This function returns 1 if bit is not between 0-7, 2 if commiting to eeprom failed and 0 if everything worked,

picoEEPROM.putBool(true, 0, 5); //saving false at bit 0 at EEPROM address 5

getBool(bit, address)

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getBool takes 2 arguments, bit at which value is stored and EEPROM address. This function returns a boolean value read from EEPROM.

bool boolRead = picoEEPROM.getBool(0, 5); //reads bool from bit 0 at EEPROM address 5

putString20(value, address)

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putString20 takes two arguments, string value and EEPROM address. This function will always take 20 bytes from EEPROM to save a given string even if it’s e.g. 4 characters long. Keep this in mind when allocating addresses. This function returns 1 if the string is larger than 20, 2 if committing to EEPROM failed and 0 if everything worked.

picoEEPROM.putString20("testingStuff", 6); //puts string starting at address 6

getString20(address)

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getString20 takes one argument, EEPROM address and returns a string read starting at that address.

String firstStringRead = picoEEPROM.getString20(6); //reads string stored at addresses 6 to 26

putString(value, address)

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putString takes 2 arguments, string of any value smaller than 4096 bytes and EEPROM address. This function returns 1 if string is larger than 4096, 2 if committing to EEPROM failed and String length! if everything worked. This data can be used with getString function.

int stringLength = picoEEPROM.putString("this string is longer than 20 characters", 27) //puts string starting at address 27

getString(string_size, address)

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getString takes 2 arguments, string length and EEPROM address. String length is returned when saving a given string to eeprom using the putString function. This function returns a string read from EEPROM.

String secondStringRead = picoEEPROM.getString(stringLength, 27); //reads string stored at addresses 27 to 27+stringLength