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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Adding External I2C EEPROM to Arduino (24LC256)

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 24c26. This allows the chip time to complete the write operation, without this if you try to do sequential writes weird things might happen.

Click to learn more. The WP pin stands for write-protected and this allows you to control if data can be written to the eeprom or not.

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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, 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 what address the chip will have depending on what we set these pins to.

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. The next argument is the address on the eeprom you want to write to and as stated above can be between 0 and 32, 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.


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.

Adding External I2C EEPROM to Arduino (24LC)

Before we get into the software part lets hook up the 24LC chip up to our Arduino. If you are using Arduino 1. To illustrate this lets follow the steps below. Leave a Reply Cancel reply Your email address will not be published.

This website uses cookies for analytics, personalization, and other purposes. The next function requestFrom sends the command to that chip to start sending the data at the address we set above.

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

Leave this field empty. This is written for Arduino versions before 1. Next we have to send the address on the weprom we want to write to. We need to send the MSB Most significant bits first so we have to shift our address to the right eight bits. 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.

Check out our videos Follow us on: Lets say we want to write to address location 20, which is in binary. 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. Next we start off just like we did with the write function by starting the process with beginTransmission and then we send the address we want to access; this works exactly the same way as the write function.

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 lets go ahead and connect the data pins to the Arduino board. Next we do a bitwise AND to get just the last eight bits. The serial reading is more fluid and influenced by the speed of the serial communication which is running to bytes per second.


We first call the Wire. Time to move on to software! Your email address will not be published. For more details Please refer to the Datasheet below. Finally we have to pass along the byte we want to store. This function takes three arguments, the device address the disk1 variablethe eeprpm address on the eeprom and the byte of data you want to write.

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. 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 argument is the address eepgom the device you want to write to, in our case we only have one device disk1 so we pass this on.

For more information please read http: The Wire library allows you to pass an integer value so we could just make a bit-wise operation to device the integer variable into two bytes.

This tutorial was originally posted on the 10kohms. See the address of the device eepprom. This is a little confusing at first so lets look at the figure below to explain the address in a little more detail. The following code allows you to write all the bytes of memory. By continuing to browse, you agree to our use of cookies as described in our Cookies Statement.

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