TWI Slave Mode Programming Quiz
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Questions and Answers

What is the first step in programming a device in slave mode using TWI?

  • Receiving data from the master
  • Sending data to the master
  • Initializing the slave address (correct)
  • Listening for the master device

Which bit needs to be set to enable the TWI module?

  • TWAR
  • TWEN (correct)
  • TWINT
  • TWEA

In FreeRTOS, how are tasks identified for scheduling?

  • By their execution history
  • By their global variable state
  • By their priorities and dependencies (correct)
  • By their return type

What is the required function prototype for tasks in FreeRTOS?

<p>void function_name(void* parameter) (A)</p> Signup and view all the answers

Which component is essential for receiving data in TWI slave mode?

<p>TWDR (D)</p> Signup and view all the answers

What is the purpose of the configMAX_TASK_NAME_LEN parameter in FreeRTOSConfig.h?

<p>It sets the maximum length for a task's name. (C)</p> Signup and view all the answers

In FreeRTOS, what happens when vTaskDelete is called with a NULL parameter?

<p>It deletes the calling task (B)</p> Signup and view all the answers

What is a characteristic of tasks in a real-time operating system like FreeRTOS?

<p>They may be periodic with time constraints (C)</p> Signup and view all the answers

What does the sStackDepth parameter represent in a task's configuration?

<p>The size of the stack allocated in terms of words. (D)</p> Signup and view all the answers

What is the purpose of the TWINT flag in TWI slave mode?

<p>To show that data was received successfully (B)</p> Signup and view all the answers

What should be done if the pvParameters value is not being used in a task?

<p>It should be set to NULL as recommended. (D)</p> Signup and view all the answers

Which function should be used for sending messages to a queue from an ISR?

<p>xQueueSendtoBackFromISR() (B)</p> Signup and view all the answers

How can the number of waiting messages in a queue be checked?

<p>Using xQueueMessagesWaiting() (D)</p> Signup and view all the answers

Flashcards

Slave Mode TWI Programming

A method of communicating with a TWI (Two-Wire Interface) peripheral in a slave role, responding to requests from a master device.

TWI Initialization

Configuring the TWI module, setting the slave address and enabling the communication.

Real-Time Operating System (RTOS)

Software that manages multiple tasks within a microcontroller, assigning execution time and prioritizing tasks for real-time applications.

Task Function Prototype

The required structure of a function that serves as a task within an RTOS. It must return void and take a void pointer.

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vTaskDelete()

An RTOS function used to delete a task, including the calling task if given a NULL parameter.

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Task States (RTOS)

Describes the different conditions a task can be in within an RTOS, such as running or not running.

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xTaskCreate()

An RTOS function used to declare functions as tasks, with specific parameters like a function pointer and a name.

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Task Priorities

Control the relative importance of tasks, ensuring that critical tasks are executed first. The concept is essential for a real time OS.

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Task name length

The maximum length of a task's name, controlled by configMAX_TASK_NAME_LEN in FreeRTOSConfig.h.

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Task stack depth

Size of the stack allocated for a task, storing its configuration and register values when not running. Measured in words (system-dependent).

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Task parameters

A value passed to the task's entry function; set to NULL if not used.

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Queue creation

Creating a queue using xQueueCreate().

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Queue sending

Sending messages to a queue with xQueueSendToBack() or xQueueSendToFront() (not from ISRs) or using ISR-compatible functions (xQueueSendToBackFromISR, xQueueSendToFrontFromISR).

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Study Notes

TWI Slave Mode Programming

  • Initialization:

    • Set the slave address in the TWAR register.
      • 7 bits for the address.
      • 8th bit (TWGCE) is 1 for answering general calls.
    • Enable the TWI module by setting the TWEN bit in TWCR to 1.
    • Enable TWI, acknowledge generation by setting TWEN, TWINT, and TWEA bits in TWCR to 1.

  • Listening:

    • Poll the TWINT flag in TWCR to detect when the slave is addressed by a master.
    • Alternatively, use TWI interrupts.

  • Sending Data:

    • Copy the data byte to the TWDR register.
    • Set TWEN, TWEA, and TWINT bits in TWCR to 1 to start sending.
    • Poll the TWINT flag to confirm complete transmission.

  • Receiving Data:

    • Set TWEN and TWINT bits in TWCR to 1 to start receiving.
    • Poll the TWINT flag to confirm reception.
    • Read the received byte from the TWDR register.

RTC Connection

  • Real-time Clock (RTC) can be connected via I2C to a microcontroller.

FreeRTOS

  • Real-time Operating System (RTOS):

    • Designed for microcontrollers.
    • Primarily written in C.
    • Multitasking system for single-processor environments.
    • Kernel schedules tasks, utilizing CPU for concurrency.
    • Scheduling policy accounts for task dependencies and priorities.
    • Event-driven and periodic tasks managed to meet time constraints.
    • System failure results from unmet task constraints.

  • Task Implementation:

    • Implemented as C functions.
    • Return type is void.
    • Takes a void pointer parameter (flexible, unspecified data type, often of address size).
    • Must use vTaskDelete() to end a task (passing NULL ends the calling task).
    • State transitions between "running" and "not running".

  • Task Creation:

    • xTaskCreate() function creates tasks.
      • pvTaskCode: Pointer to the task function.
      • pcName: Descriptive task name (for debugging). Limited length (configMAX_TAKS_NAME_LEN in FreeRTOSConfig.h).
      • usStackDepth: Task stack size (number of words).
      • pvParameters: Optional parameter passed to task function (default NULL).

  • Queues:

    • Created with xQueueCreate().
    • Data can be added to the back or front of the queue using xQueueSendtoBack() or xQueueSendtoFront().
    • Use xQueueSendtoBackFromISR() or xQueueSendtoFrontFromISR() for sending from Interrupt Service Routines (ISRs) to avoid issues.
    • xQueueMessagesWaiting() monitors queue size.

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Description

Test your knowledge on TWI slave mode programming including initialization, data transmission, and reception. This quiz also touches on RTC connections through I2C with microcontrollers and FreeRTOS. Challenge yourself and see how well you understand these essential concepts!

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