The PS2 keyboard uses a simple synchronous serial protocol using only two wires for communication. Due to its simplicity the PS2 keyboards are widely used with simple microcontroller based boards also. The PS2 keyboard always acts as a slave device which can send the equivalent ASCII value of the key which has been pressed to its master device which can be a PC or a microcontroller.The SD memory card comes in large storage capacities from 1 GB up to 32 GB are available. They are used mostly in costly devices like digital camera, media players etc. The SD memory cards are interfaced in high end devices using SD bus which provides very high speed data transfer between the device and the memory card.  They also can be interfaced with a device using the low speed and comparatively simple SPI bus and hence they are widely used in microcontroller based system also. 

There are so many devices available which can record and playback voice. Most of the digital devices like mobile phones can use the SD card to record the voice signals and playback. This project demonstrates how to record voice signals on a micro SD card and play it back using the GR SAKURA board. Voice signals are continuous analog signals and the digital devices like microcontrollers cannot handle the continuous analog signals. Most of the microcontrollers have an ADC module which can do analog to digital conversion. The microcontroller uses sampling technique to convert the continuous analog signals to discrete digital equivalent samples. While recording the voice, the GR SAKURA board samples the voice signals and writes the sampled values to a file at the sampling time itself. The same file is opened again and reads the values at the same frequency at which they are sampled.  

The microcontroller systems may have to back up the data which they have read during their operation or the data which they need to access during their running time. Most of the microcontrollers have built-in EEPROM memory but they come in comparatively small sizes. In order to use the microcontroller in applications like file accessing, media player etc. an external memory card is necessary. The SD memory card comes in large storage capacities ranging from 1 GB to 8 GB and they are compatible with the SPI bus of the microcontroller. The large storage capacity and simplicity in interfacing results in wide usage of SD memory card by the microcontrollers. The files in an SD memory card are stored using FAT32 or FAT16 and one should use the code or FAT file-system library to access the files from an SD card. 

The SD memory card comes in large storage capacities from 1 GB up to 32 GB are available. They are used mostly in costly devices like digital camera, media players etc. They are also found in low cost and simple micro-controller based systems. The SD memory cards are interfaced in high end devices using SD bus which provides very high speed data transfer between the device and the memory card.  They also can be interfaced with a device using the low speed and comparatively simple SPI bus and that is the reason why the micro-controller system developers are interested in it. Due to their large storage capacity the SD card can be used to continuously store data bytes which may be read by the system from a sensor since a long period of time. The data can be directly written in the storage locations of the SD card or it can be written into a file inside the SD card.  

This project explains how to interface the SD card with an AVR microcontroller. In this project an ATMEGA16 microcontroller is used. The microcontroller runs on 5V power supply with a built in crystal frequency of 8 MHz. A 2GB SDSC card from Transcend is used in this particular project, but the code will work with most of the SD cards. The SD card is formatted with FAT32. The ultimate aim of this project is to read a file from the FAT32 file system of the SD card.The SD card has been formatted as FAT32 before interfacing. The generalized code for the FAT32 is written to interface the SD card. Explanations of the FAT32 file system and how to access files from these file system is explained in this project.This project explains the SD card interfacing with an AVR microcontroller and circuit working in detail. Read more to find out how this project works and do it yourself!!! 

Secure Digital (SD) format is used by all major digital memory manufacturing companies of the world including giants like Sony and Siemens. SD cards are available in various memory capacities, sizes and data transfer speeds. The maximum size of the cards is that of SD or SD HC cards and the smaller ones require an adapter that scales them exactly to the size of a standard SD card.While most modern Laptops come with inbuilt SD card readers, devices that have only USB inputs require some kind of reading device to access or modify the data in the cards. SD card readers solve this purpose. SD card can be inserted inside the card slot in the readers which have a USB interface to connect to the desktop. 

The Secure Digital (SD) Card or more commonly known as memory cards are small size storage devices that are specially designed to store and transfer data from audio and video consumer electronic devices like digicam, cell phones, voice recorders etc. They are known as secure digital card because they include a copyright protection mechanism that complies with the security of the SDMI (Secure Digital Music Initiative) standards. In this mechanism, a mutual authentication and encryptions are used to protect the card content from illegal usage.  The notch in the tip right corner of the card helps to identify the right way of attaching with the device. As per the standards, each SD card is formatted with a File Allocation Table (FAT) file system, which allows every operating system to access the files in that system. 

This project explains how to interface the SD card with an AVR microcontroller. In this project an ATMEGA16 microcontroller is used. The microcontroller runs on 5V power supply with a built in crystal frequency of 8 MHz. A 2GB SDSC card from Transcend is used in this particular project, but the code will work with most of the SD cards. The SD card is formatted with FAT32. The ultimate aim of this project is to read a file from the FAT32 file system of the SD card.The SD card has been formatted as FAT32 before interfacing. The generalized code for the FAT32 is written to interface the SD card. Explanations of the FAT32 file system and how to access files from these file system is explained in this project.This tutorial explains the SD interfacing with an AVR card working in detail. Read more to find out how this project works and do it yourself!!!