Comunicación Serie - Capitulo 4 - Comunicación vía UART método de interrupciones

Communication via UART Using Interrupts

Introduction to Interrupts

• The video assumes prior knowledge of interrupts and their benefits, as well as previous chapters on UART communication configuration.

• A single function will handle all possible interrupt sources, including data received, data transmitted, or errors.

Function Naming Conventions

• Different microcontrollers may have specific naming conventions for interrupt functions; for example, LPC845 uses predefined names like uart0_isr.

• It's important to ensure that the same function can handle multiple UART channels while maintaining similar behavior across different microcontrollers.

Mechanism of Interrupt Communication

• The mechanism of interrupt-driven communication is outlined to help understand its functionality.

• Upon receiving the first byte, an interrupt is triggered which calls the corresponding interrupt service routine (ISR).

Status Register Analysis

• To determine what caused the interrupt, the status register must be checked for active flags indicating received data or errors.

• Functions handling interrupts should be brief and generic enough to be reused across various projects without losing efficiency.

Data Handling in Main Application Thread

• Data received during an interrupt must be passed to the main application thread without blocking it; using a circular buffer is recommended.

• The buffer size should depend on the type of data being processed and should allow for efficient insertion and extraction operations.

Error Management During Reception

• Errors encountered during reception need to be logged into the buffer alongside valid data for later processing by the main thread.

• It’s crucial to clear error flags after logging them into the buffer to prevent misinterpretation during subsequent operations.

Structuring Received Data with Errors

• A structure can be created where each entry consists of both valid data and any associated error information.

• This approach allows differentiation between normal data values and error codes when processing incoming information.

Simplifying ISR Implementation

• Modifications are made in how received data is stored within ISRs; initializing variables properly ensures clarity in handling both valid data and errors.

Transmission Process Overview

• The transmission process begins when there’s a need to send a character through TXD; this requires checking if TX ready flag is set before writing new data.

Enabling Transmission Interruptions

• Transmission interruptions should only be enabled when there’s actual data available in the buffer; otherwise, unnecessary interrupts could occur.

Buffering Outgoing Data

• A separate transmission buffer (TX Buffer), potentially equal in size to reception buffers, facilitates smooth communication between application threads and ISRs.

Writing Data into Transmission Buffer

• When sending strings or sequences of characters, they are written sequentially into the transmission buffer until reaching a null terminator.

Managing Transmission State Flags

• A global flag indicates whether transmission is ongoing; this helps manage enabling/disabling interrupts appropriately based on current state.

Finalizing Transmissions

• Once all characters are sent from TXD, it's essential to disable further transmission interrupts until new data needs sending again.

Conclusion on Managing Multiple UART Channels

• Considerations arise regarding managing multiple UART channels efficiently through structured programming practices that minimize redundancy while maximizing functionality.