The Microchip Technology Inc. 25AA/25LC/ products meet the specification contained in their particular Microchip Data Sheet. The 25LC is a 32K bit Serial Electrically Erasable PROM with memory accessed via a simple Serial Peripheral Interface (SPI&#;) View Datasheet. 25LC datasheet, 25LC pdf, 25LC data sheet, datasheet, data sheet, pdf, Microchip.

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A microcontroller normally has 40 or more pins since the input and output operations occur directly from the chip. They start with a ” ” and do not end with semi-colons.

The device also offers various degerees of write protection and a hold pin, but we won’t be covering those in this tutorial. Write and read functions are available with and without address setting. The RAM would normally lose its contents when power is removed, however the NVRAM is manufactured with a built in battery which keeps power applied to the memory after power has been removed from the product.

Serial Peripheral Interface SPI is a synchronous serial data protocol used by Microcontrollers for communicating with one or more peripheral devices quickly over short distances.

EPROM Programmer Device Support

In this mode, 8 bits arranged memories require 8 pins from the micro-controller which is too much pins consuming even though the gain in speed is noticeable.

Within the 25LC family, some references are getting obsolete and Microchip suggests to use the A versions instead. Control registers code control settings for various microcontroller functionalities. We send the 16 bit address to begin writing at in two bytes, Most Significant Bit first. Most devices, regardless of the technology family, can 25lx320 identified by their CORE part number. We end the setup function by sending the word “hi” plus a line feed out the built in serial port for debugging purposes.


The datasheeh below describes how to determine a typical core part number. With an SPI connection there is always one master device usually a microcontroller which controls the peripheral devices. My preference goes to SPI datasheeet spite of the highest number of pin required.

This is accomplished by sending the required command, address and data serially one bit at a time over single pins instead of the multiple pins of a parallel part.

They differ from their supply voltages:. The first step is setting up our pre-processor directives. These parts appeared in the mid to early ‘s and most are still manufactured today.

Next is a short recap of the chip properties Reference Max. These modes control whether data is shifted in and out on the rising or falling edge of the data clock signal, and whether the clock is idle when high or low. In the control register each bit sets a different functionality.

Arduinoos » Blog Archive » Memory (Part 3)

The images 25lc20 the bottom right are close-up views of the first three eprom packages. This function could easily be changed to fill the array with data relevant to your application:. The CORE part number is easily identified and has been hi-lited. Mainly two types of serial communication protocols are available: Note that we use the WREN opcode we defined at the beginning of the program.

In the main loop it reads that data back out, one byte at a time and prints that byte out the built in datasheet port. This deselects the device and avoids any false transmission messages due to line noise:.


This approach allows you to more easily locate a device number, as many users do not know the manufacturer of the device in which they have interest. Here we allocate vatasheet global variables we will be using later in the program. Due to the number of device manufacturers, the catagories below are organized by technology family and device pin count. Although not as fatasheet, serial eeproms and nvrams find use in many products due to their small size and low cost.

Opcodes are control commands:. These parts must be erased before programming.

25AA320/25LC320/25C320 PDF Datasheet浏览和下载

The NV stands for non-volatile. This way if our data comes out looking funny later on we can tell it isn’t just the serial port acting up:. Remember, a core part number usually represents hundreds of actual part numbers due to different manufacturers, speeds, temperatures, package types and other chip characteristics. Coming next after the 25LC chips are the 25AA chips. Usually each bit in a control register effects a particular setting, such as speed or polarity. It’s memory is organized as pages dwtasheet bytes each.

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Data Sheets

Arduinoos Get the most out of the least. Although not used in new designs, these parts are still commonly found in older products and equipment.

Next is a short recap of the chip properties. Next post on same subject.