Set the I/O pins to the data that is to be stored.Set the address to write to by setting the address pins.Writing data to an EEPROM is also simple and requires the following steps: When these conditions are met, the I/O pins output the byte stored at the address pointed to by the address pins. Reading data from an EEPROM is very simple and only requires that the address pins are set to the desired address, the chip select is held low, and the OE pin is held low. Both the WE and OE pins are active low and therefore should always be held at VCC until data is to be accessed. When the chip select is pulled to ground, the chip becomes selected. While the address pins are active high, the chip select is active low this means when the chip is not being used, the chip select needs to be set to VCC. The table below shows how the address pins can be changed to select different memory locations:īefore data can be written or read, two things need to be done first - we must select the chip and set the address pins. Each memory location has a unique location, and this location has a number that can be selected by using the address pins. Memory chips store data in specific memory locations that can be written and read. NC – These are left unconnected (Not Connected).CS Pin – The Chip Select Pin, used to select the memory chip for accessing.OE Pin – The Output Enable Pin, used to read a byte from a memory location.WE Pin – The Write Enable Pin, used to write a byte to a memory location.I/Ox Pins – Data pins, used to store/retrieve information from the chip.
Ax Pins – Address pins, used to select a specific memory location.Parallel EEPROM chips like the AT28C64B have different inputs/outputs that all perform different actions. One of the advantages of the AT28C64B is that the IC package uses a common industry pin layout that makes it compatible with many other memory chips, which means that if a parallel memory chip replacement is needed, then the AT28C64B can be used.
In this tutorial, we will use the AT28C64B, which is an 8KB memory chip that stores information even when the power is turned off.
ARDUINO MEGA EEPROM PROGRAMMER SERIAL
Parallel memory has some advantages and disadvantages when compared to serial memory, and each memory category is the polar opposite to the other. For example, an 8-bit parallel memory chip will store/retrieve one byte of data in one read cycle, whereas an 8-bit serial memory chip will require 8 cycles to either store or retrieve a single byte. Serial memory involves storing digital information one bit at a time and is streamed to and from a memory device, whereas parallel memory stores an entire word of memory in one go. However, no matter how information is stored, memory storage will always fall into one of two categories: serial or parallel. For those who want to look at more modern solutions, there are plenty of memory chips on the market with different protocols. For those who feel like going entirely retro, there are magnetic tapes in the form of cassette tapes. When it comes to storing information separately from a microcontroller or SoC, there are many different methods available to makers.
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