5 ms max for 24LC and 24C – 10 ms max for 24AA 24C ( 24xx*) is a 32K x 8 (K bit) Serial Elec- CMOS Serial EEPROM. I2C is a . Adding External I2C EEPROM to Arduino (24LC). This tutorial was originally posted on the website, which now seems to be no longer with us. Buy low price, high quality 24c eeprom with worldwide shipping on

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Before we get into the software part lets hook up the 24LC chip up to our Arduino. Next we start off just like we did with the write function by starting the process with beginTransmission and then we send deprom address we want to access; this works exactly the same way as the write function. Next we do a bitwise AND to get just the last eight bits.

Adding External I2C EEPROM to Arduino (24LC)

The 24LC gets the data and writes the data to that address location. The next function requestFrom sends the command to that chip to start sending the data at the address we set above.

Next lets go ahead and connect the data pins to the Arduino board. The first argument is the address of the device you want to write to, in our case we only have one device disk1 so we pass this on. Then connect the SCL pin 6 to pin 5 on the Arduino. Arduino Sketch Below is the entire tutorial code, scan over it and see if you understand it before I dive into what each section does.

This means our 24LC chip gets the address and then which tells it to store the next byte in address location 20, This tutorial was originally posted on the 10kohms.

Working on 24C256 EEPROM 256Kbit / 32 Kbyte Serial Memory Data Storage on i2C Bus

This allows the chip time to complete the write operation, without this if you try to do sequential writes weird things might happen. The next three bits A2,A1,A0 are the important bits that we can change so lets look at the simple table below to see 24c526 address the chip will have depending on what we set these pins to. The WP pin stands for write-protected and this allows you to control if data can be written to the eeprom or not.


Leave this field empty. This is written for Arduino versions before 1. For the purpose of explaining how the address works we can ignore the Start and Acknowledge bits.

If you are using Arduino 1.

Adding External I2C EEPROM to Arduino (24LC256)

Leave a Reply Cancel reply Your email address will not be published. Some of microcontroller have limited storage like Arduino it has only bytes data space compare 242c56 AT24C has Kb EEPROM will be very suitable for small amount of data storage or extending data storage for your microcontroller.

This variable is not required but it allows us to easily change the address we want to access without going through all of the code and replacing the value. Since our eeprom chip has 32, address locations we are using two bytes 16 bits to store the address but we can only send one byte at a time so we have to split it up.

Your email address will not be published. The next argument is the address on the eeprom you want to write to and as stated above can be between 0 and 32, This website uses cookies for analytics, personalization, and other purposes. By continuing to browse, you agree to our use of cookies as described in our Cookies Statement.

We first call the Wire. Click to learn more. Using the image above as a guide lets begin to wire the chip. After our data and power pins are connected we have four left on 24LC chip, the WP pin and the three address pins.

The 24C is optimized for use in minimal storage applications where low-power and low-voltage operation, driven using i2C serial communication bus to help you do much more multiple series of storage.


The arguments it accepts are the same first two arguments the write function, the device address and the address on the eeprom to read from. Next we have to send the address on eepprom eeprom we want to write to.

Lets say we want to write to address location 20, which is in binary. Check out our videos Follow us on: The Wire library allows you to pass an eeproom value so we could just make a bit-wise operation to device the integer variable into two bytes.

Finally we have to pass along the byte we want to store.

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The following code allows you to write all the bytes of memory. Time to move on to software! See the address of the device below. With the address pins connected the hardware part of this tutorial is complete and every pin of the 24LC should be connected to either Vcc, GND or the Arduino. The first send function takes the eeaddress and shifts the bits to the right by eight which moves the higher end of the 16 bit address down to the lower eight bits.

For more details Please refer to the Datasheet below.

To illustrate this lets follow the steps below. Below is the entire tutorial code, scan over it and see if you understand it before I dive into what each section does. For more information please read http: As you can see the diagram above the pin A0, A1, A2 are connected to the ground these pins allow you to customize the device i2C bus address, below the data sheet we that we verify how it is formed the byte address.