Control Word is an instruction or command send to to set its ports or pins as input, output or interrupt driven. It is used with many microprocessors and microcontrollers for various purposes. The device has three 8-bit ports port A, port B and port C. These ports can be used as input or output. These ports are further divided in to two groups A and B.
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Control Word is an instruction or command send to to set its ports or pins as input, output or interrupt driven. It is used with many microprocessors and microcontrollers for various purposes. The device has three 8-bit ports port A, port B and port C. These ports can be used as input or output.
These ports are further divided in to two groups A and B. Each group further has ports. Group A is comprised of port A and port C upper nibbles pins 7, 6, 5, 4 control. Group B contains port B and port C lower nibble 0, 1, 2, 3. Vcc Apply 5 volts to this pin. WR write A low on this pin indicates that we want to write to A0 and A1 These both pins select the ports. Combination of high and low level signal on these pins selects the ports A, B and C.
Not only these pins are used to select port but also can write control word in device. There are three modes in which the device can be used. Mode-0 Mode-1 Mode In mode 0 each group can be used as input or output. Port A , port B and port C can be used as input or output. Question arises how we can do so. Just send a control word to and it will set itself according to your control word.
The control word for mode 0 is like this. D7 will always be high for mode 0. For selecting all ports as output the control word will be 0x80 in hexadecimal, or in binary. In mode 0 you can also access individual bits of port C.
For bit set reset mode D7 will always be 0. In mode 1 each group can be used as 8-bit input or output data bus and the remaining 4-bits are used as handshaking and interrupt control signals. Port A is used with port c upper three bits and port B is used with port c lower 3 bits. The remaining 2 bits of port C can be used as control signals. For more details on mode 1 download the data sheet released from Intel from the links below. Mode 2 is a bidirectional bus mode it is used very rarely.
Mode 2 is used with port A only and port C is used for interrupt and control signals only. Microcontroller Projects Related to A. Practical Examples with Code. Connect with Engineers Garage on Social Media. Search Engineers Garage.
The Intel or i Programmable Peripheral Interface PPI chip was developed and manufactured by Intel in the first half of the s for the Intel microprocessor. The is a member of the MCS Family of chips, designed by Intel for use with their and microprocessors and their descendants. The functionality of the is now mostly embedded in larger VLSI processing chips as a sub-function. All of these chips were originally available in a pin DIL package. Address lines A 1 and A 0 allow to access a data register for each port or a control register, as listed below:.
Intel 8255A - Pin Description