Mode Instruction Format of Programmable Communication Interface PIC 8251

TL;DR

This video explains the mode instruction format of the A251 programmable communication interface used for parallel to serial and serial to parallel data conversion.

Transcript

hello friends in this video we will study the mode instruction format of a251 programmable communication interface which is sometimes also known as universal synchronous asynchronous receiver transmitter or usa rp so let us start with our topic the 825 fund programmable communication interface is used by the microprocessors when it is communicating... Read More

Key Insights

• 🎭 The A251 programmable communication interface performs parallel to serial and serial to parallel data conversion for microprocessors.
• 🔑 Control words, including the mode instruction, are written by the microprocessor to determine the functions of the A251.
• 📳 The mode instruction determines the mode (synchronous or asynchronous), stop bit length, character length, parity, baud rate factor, and synchronization.
• ☠️ In asynchronous mode, the baud rate factor and character length are determined by specific combinations of bits in the control word.
• 🫦 The external sync detect bit controls external synchronization in synchronous mode.
• 🫦 The A251 operates with 8-bit control words, with different bits defining various functions such as parity, stop bits, and synchronization.
• 😫 The mode instruction sets the A251's initial functions after a reset.

Questions & Answers

Q: What is the purpose of the A251 programmable communication interface?

The A251 is used by microprocessors to convert parallel data to serial data for communication with peripherals.

Q: How does the microprocessor determine the functions of the A251?

The microprocessor writes control words, including the mode instruction, to the A251's control register to determine its functions.

Q: What are some functions determined by the mode instruction?

The mode instruction determines synchronous or asynchronous mode, stop bit length, character length, parity bit, baud rate factor, and synchronization.

Q: How many bits are in the mode instruction format?

The mode instruction format is an 8-bit format.

Q: What is the baud rate factor determined by in the asynchronous mode?

The baud rate factor is determined by the values of the d0 and d1 bits in the control word, with options of 0 0, 0 1, 1 0, and 1 1 representing sync mode, 1x, 16x, and 64x times the clock frequency, respectively.

Q: How is the character length determined?

The character length is determined by the values of the d2 and d3 bits in the control word, with options of 0 0, 0 1, 1 0, and 1 1 representing 5, 6, 7, and 8 bits, respectively.

Q: What is the purpose of the parity enable and even parity generator bits?

The parity enable bit determines whether parity is enabled or disabled, and the even parity generator bit determines whether even or odd parity is generated.

Q: What does the external sync detect bit control in the synchronous mode?

The external sync detect bit controls the synchronization mode, with a value of 1 indicating external synchronization.

Summary & Key Takeaways

• The A251 programmable communication interface is used by microprocessors to communicate with peripherals, converting parallel data to serial data for data transfer.

• The microprocessor writes control words to the A251 to determine its functions, specifically the mode instruction and command instruction.

• The mode instruction sets the functions of the A251, such as synchronous or asynchronous mode, stop bit length, character length, parity bit, baud rate factor, and synchronization.