NOOB'S INTRODUCTION TO MICROCONTROLLER

Well many people ask me how should i approach micro controllers, how can i get a good understanding of them and develop logic and programming skills.
Face it you are a electronic hobbyist and you want to create something new to play with so for all those who want to get started with micro controllers follow these simply rules and you will be pro's in no time.

RULES:

1. Search:

Well searching is something very important, by searching we can find people who share similar interest or simply find projects followed with comments or simple we find ideas to begin or learn something all new.

2. Start with simple micro controllers:

Now lets pick a good micro controller to start with i say go for 8051 or ARDUINO as a start up. But to tell the truth i like to start with 8051 as it freely available and teaches you core basics of micro controllers. Its one of the most popular micro controller out in the market. Apart from being mostly used it has a large form support,large number of projects online to start with. Start with Assembly language(8051 NOT ARDUINO) and move to C by this technique you will understand the flow of the code and can tell what's happening inside a micro controller at any time. This will teach you how electronic gadgets/robots etc work how to design a gadget/Robot and help you to design codes in blocks called modular programming. YOU CAN ALSO LOOK FOR DEVELOPMENT BOARDS i am not going to tell about them today as it needs a good explanation, so i will arrange them on some other day.

  

3. Learn basics:

Well most people think working on micro controller's are tough, but the truth is its opposite, working with simple components is tough as they don't work on 0's and 1's so controlling them require knowledge of the component and working principle's related to it and basic circuit diagram to start understanding.I will really stress when you work with basic try to understand how potential and current is varying in the circuit this will give you very good understanding how a circuit works and will help you to design complex circuits.

SERIAL PERIPHERAL INTERFACE [SPI]:

IN TODAY'S POST LETS SEE WHAT IS SPI. For programming part see SPI tutorial in Arduino

introduction:

Serial peripheral interface [SPI] is an interface bus commonly used to send data b/w microcontroller and small peripherals such as shift registers, sensors, SD cards and other controllers.It uses separate clock and data lines and differentials devices using select lines.

What's the difference b/w Serial Ports?

Serial ports normally use TX and RX lines which are "asynchronous"and there is no control over when data is sent or Guarantee that they are receiving the data at the same time or following at a same rate. So they should have same clock  else they will not communicate properly. So to handle this problem asynchronous serial connections add extra start and stop bits to each byte to help receiver to sync with each other.

(By the way, plz  noticed that "11001010" does not equal 0x53 in the above diagram.Serial protocols will often send the least significant bits first, so the smallest bit is on the far left.The lower nubble is actually 0011=0x3, and upper nybble is 0101=0x5.)

SPI: AS SOLUTION

SPI works in a slightly different manner. it's a "synchronous" data bus, which means that it uses separate lines for data and a "clock" that keeps both sides in perfect sync. The clock acts like a indicator to the receiver. HOW WILL THE RECEIVER KNOW WHEN THE DATA IS COMING? ITS SIMPLE IT KNOW THAT BOTH THE CLOCK AND DATA COME AT THE SAME TIME.

One reason that SPI is so popular is that the receiving hardware an be a simple shift register. This is a much simpler piece of hardware that the full-up UART (Universal Asynchronous Receiver/ Transmitter) that asynchronous serial requires.

Receiving Data:

Sending data may seem really simple where as Receiving data is slightly complicated.In SPI, only one side generates the clock signal (usually called CLK or SCK for Serial Clock). The side which generates the clock is called the "master", and the other side is called the "slave" which can be many.

When data is sent from the master to a slave, it's sent on a data line called MOSI, for "Master Out/ Slave In". If the slave needs to send a response back to the master, the master will continue to generate a prearranged number of clock cycles, and the slave will put the data onto a third data line called MISO, for "Master In / Slave Out".

Notice we said "prearranged" in the above description.We know when the master gets the data from the slave so we need to give clock cycles at that moment to receive them.For example we know by sending command "read data " we know some data is coming so we will allot some clock cycles.

Slave Select(SS):

Now the last pin we need to know is the Slave Select which tells the device when to wake up and receive or send data.

This line is active low that means we need to give a "logic 0" to enable it.Now how to use it ?

When sending a data we make the pin low and send the data after sending we make the pin high and disconnect the device.

Multiple Slaves:

1. By giving each slave a separate SS lines. By enabling and disabling that SS line we can control that particular slave.

Tips:

• Because of the high speed signals, SPI should only be used to send data over short distances.
• For long distance communications decrease the clock speed and consider using SPI drivers etc.