24C256 EEPROM PDF
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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This tutorial was originally posted on the 10kohms.
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Before we get into the software part lets hook up the 24LC chip up to our Arduino. Using the image above as a guide lets begin to wire the chip.
eeprkm Next lets go ahead and connect the data pins to the Arduino board. Then connect the SCL pin 6 to pin 5 on the Arduino. After our data and power pins are connected we have four left on 24LC chip, the WP pin and the three address pins.
Adding External I2C EEPROM to Arduino (24LC)
The WP pin stands for write-protected and this allows you to control if data can be written to the eeprom or not. This is a little confusing at first so lets look at the figure below to explain the address in a little more detail. For the purpose of explaining how the address works we can ignore the Start and Acknowledge bits. 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.
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. Time to move on to software! For more information please read http: Below is the entire tutorial code, scan over it and see if you understand it before I dive into what each section does.
This is written for Arduino versions before 1. If you are using Arduino 1. 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.
This function takes three arguments, the device address the disk1 variablethe memory address on the eeprom and the byte of data you want to write. The first argument is the address of the device you eeprom to write to, in our case we only have one device disk1 so we pass this on.
Adding External I2C EEPROM to Arduino (24LC256)
The next argument is the address on the eeprom you want to write to and as stated above can be between 0 and 32, Finally we have to pass along the byte we want to store. We first call the Wire. Next we have to send the address on the eeprom we want to write to. Since our eeprom 24256 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.
Working on 24C256 EEPROM 256Kbit / 32 Kbyte Serial Memory Data Storage on i2C Bus
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. Next we do a bitwise AND to get just the last eight bits. To illustrate this lets follow the steps below. Lets say we want to write to address location 20, which is in binary. We need to send the MSB Most significant bits first so we have to shift our address to the right eight bits. This means our 24LC chip gets the address and then which tells it to store the next byte in address location 20, The 24LC gets the data and writes the data to that address location.
This allows the chip time to complete the write operation, without this if you try to do sequential writes weird things might happen. 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 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 next function requestFrom sends the command to that chip to start sending the data at the address we set above. 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.
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