new to electronics!!!!!plz help

[tech_vaibhav_eee]

what is spi(serial peripheral interface) used for??how is it different from uart and 12c??

 

[gramo]

Typically SPI has three wires, DATA, CLK and CS (Chip Select)

The data is clocked through the DATA wire at a speed determined by the CLK signal. SPI can go extremely fast, in some applications it operates in Mhz.

There are different configurations for connecting multiple devices, but Google is probably best for that, better yet, wiki.

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I2C uses only two bidirectional open-collector lines, serial data (SDA) and serial clock (SCL), pulled up with resistors. The maximum voltage is +5 V, although +3.3 V systems are common and other voltages are permitted.

The I2C reference design has a 7-bit address space with 16 reserved addresses, so a maximum of 112 nodes can communicate on the same bus. The most common I2C bus modes are the 100 kbit/s standard mode and the 10 kbit/s low-speed mode, but clock frequencies down to zero are also allowed.

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UART is the backbone of most serial applications from my experience. Its fast, and very easy to use, especially when used in conjunction with a higher language compiler such as Swordfish.

UART is the acronym for universal asynchronous receiver/transmitter. Many modern ICs now come with a UART that can also communicate synchronously; these devices are called USARTs.

This method of data transfer relies on data being transmitted in the form of voltage swings at a known baud (bits per second). Both the Master and Slave devices must know what the baud is or else the reception of the data will be corrupted if not possible at all.

 

[erosennin]

I2C also gets angry when you try to use it over long distances (>7m), and you should use a I2C booster IC.
UART doesn't seem to have this problem, at least not for much greater distances, 100's of meters with decent cable.
I don't know much about SPI....