DIFFERENT TYPES OF REGISTERS

BINARY CELL:

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A binary cell is a memory allocation element that can store one bit of information(1 or 0).
We have Binary cell with logic '1' and logic '0'. A binary cell is referred as bit.

REGISTER:

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A set of binary cells is called a register. A register is characterized by
1)name of the register.
2)number of binary cells in it.

Different types of Registers

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DDR,PIN and PORT registers are frequently used in coding of an MC.
These registers are used to give instructions to the MC as of which pins are used as input/output pins.

1.DDR-Data Direction Register

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→This register is used to tell us about which pins in a particular port are to be used as input pins and which pins are to be used as output pins.
→Setting a bit in the DDR register to logic 1 will makes the corresponding pin as output pin.→Setting a bit in the DDR register to logic 0 will make the corresponding pin an input pin.
Ex:1)DDRA=0b11110000
the above statement means that the first 4 pins of port A(PA0-PA3) are set as input pins and the last four(PA4-PA7) are set as output pins.

2.PIN Register

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→This register is used for the ports that are configured as the input ports.
→The inputs at each pin of the input port are stored in this PIN register.
→Setting a bit as logic 1 in PIN register means that,that particular pin in that specified port has been used for input operation.

→Setting a bit to logic 0 means that,that particular pin in that specified port has not been used to give input.
Ex:1)PINA=0b11110000
the above statement means that first 4 pins are not used to give input and the other 4 have been used to give input.

3.PORT register

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→This register is used for the ports that are configured as the output ports.
→The outputs at each pin of the port are stored in the PORT register.
→Setting a bit as logic 1 in this register means that,that particular pin in that specified port has been used to take the output.
→Setting a bit as logic 0 means that,that particular pin in that specified port has not been used to take the output.
Ex: 1)PORTA=0b11110000
The above statement means that first 4 pins have not been used to take output..but other pins have been used.