GPIO Control Registers Quiz
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Questions and Answers

What configuration is required to set Port B Pin 14 as an output push-pull?

  • GPIOB_OTYPER = 1
  • GPIOB_OTYPER = 0 (correct)
  • GPIOB_OTYPER = 3
  • GPIOB_OTYPER = 2

    • Which statement about open-drain mode is true?

  • It allows uni-directional communication among multiple devices.
  • It can only interface devices of the same voltage level.
  • It allows bi-directional communication using a single wire. (correct)
  • It can only connect devices in a series configuration.

    • How can open-drain mode assist with interfacing between devices of different voltage levels?

  • It maintains a constant voltage across all connected devices.
  • It allows devices to communicate by pulling the line low. (correct)
  • It functions by changing the voltage of each device individually.
  • It synchronizes the clock signals across devices.

    • What advantage does using STM32 internal pull-up in open-drain mode provide?

    <p>It ensures that the line is high when no devices are pulling it low.</p> Signup and view all the answers

    In a system utilizing open-drain configuration for multiple devices, what does multicast refer to?

    <p>One device sends data while multiple devices receive.</p> Signup and view all the answers

    What does the input data register (IDR) do when a GPIO pin is configured in input mode?

    <p>It allows reading the logic level of the pin.</p> Signup and view all the answers

    Which register allows manipulation of output data register (ODR) bits atomically?

    <p>GPIOx_BSRR</p> Signup and view all the answers

    When reading the GPIO output data register (ODR), what can be done?

    <p>Read back the output to confirm it was set correctly.</p> Signup and view all the answers

    What is the effect of writing a '1' to the GPIOx_BRR register?

    <p>It resets the corresponding ODy bit to 0.</p> Signup and view all the answers

    The GPIOx_IDR shows reserved bits in which range?

    <p>Bits 31:16</p> Signup and view all the answers

    In which mode does the ODR determine the logic level of a GPIO pin?

    <p>Output mode</p> Signup and view all the answers

    Which of the following GPIO registers is write-only?

    <p>GPIOx_BRR</p> Signup and view all the answers

    What is the function of the GPIOx_BSRR register?

    <p>To set and reset bits in the ODR.</p> Signup and view all the answers

    What happens when both the BSy and BRy bits are set in the GPIOx_BSRR register?

    <p>BSy takes priority, setting the corresponding ODy bits.</p> Signup and view all the answers

    Which header file contains declarations used for GPIO peripheral in the HAL library?

    <p>stm32l4xx_hal_gpio.h</p> Signup and view all the answers

    If a sensor provides a 16-bit value in two separate bytes, what must be done to interpret the output correctly?

    <p>Concatenate the bytes to form a single 16-bit value.</p> Signup and view all the answers

    What is necessary for the HAL_GPIO_WritePin() function to work successfully on a pin?

    <p>The pin must be configured as Output in the Mode Register.</p> Signup and view all the answers

    In the context of GPIOx_BSRR, what does a value of 0 for either BSy or BRy indicate?

    <p>No action is taken on the corresponding ODy bit.</p> Signup and view all the answers

    In converting raw sensor values, what type of function is often used to determine the physical quantity's magnitude?

    <p>A conversion function that may be linear or nonlinear.</p> Signup and view all the answers

    What does the GPIOx_ODR register represent?

    <p>The output data for the GPIO pins.</p> Signup and view all the answers

    Which protocol is commonly associated with sensors sending data in 8-bit chunks?

    <p>I2C</p> Signup and view all the answers

    What is the function of the GPIOx_MODER register?

    <p>To configure the mode of pins for a given port</p> Signup and view all the answers

    Which value in the GPIOx_MODER bits indicates a pin is set to analog mode?

    <p>11</p> Signup and view all the answers

    What does a value of '01' in the GPIOx_MODER bits signify?

    <p>The pin is a general-purpose output</p> Signup and view all the answers

    How many bits are used per pin in the MODER register for configuration?

    <p>2 bits</p> Signup and view all the answers

    In the GPIOx_MODER register, what configuration is represented by '10'?

    <p>Alternate function mode</p> Signup and view all the answers

    What is the address offset for the MODER in the GPIO Control Register?

    <p>0x00</p> Signup and view all the answers

    Which of the following describes the reset state of a GPIO pin?

    <p>Analog mode</p> Signup and view all the answers

    For how many ports does a MODER register provide pin configuration?

    <p>Up to 16 ports</p> Signup and view all the answers

    What is the purpose of the pull-down configuration in GPIO input settings?

    <p>It sets the default input state to LOW.</p> Signup and view all the answers

    Which output type allows multiple outputs to be connected to a single bus?

    <p>Open-drain output</p> Signup and view all the answers

    What happens when a GPIO pin is set to weak HIGH (disconnected) in an open-drain configuration?

    <p>The pin will be in a floating state.</p> Signup and view all the answers

    What register is needed per port to manage the output type for each pin?

    <p>GPIOx_OTYPER</p> Signup and view all the answers

    In the GPIO control register, which function is reserved and must not be written to?

    <p>Pin 11</p> Signup and view all the answers

    When a GPIO pin is set to push-pull output, which of the following is true?

    <p>It can drive either a strong HIGH or strong LOW.</p> Signup and view all the answers

    How many bits are required in the OTYPER register to control the output type for an entire port?

    <p>16 bits</p> Signup and view all the answers

    What happens when the PUPD bits are set incorrectly?

    <p>The GPIO functionality will be compromised.</p> Signup and view all the answers

    Study Notes

    GPIO Control Registers

    • GPIOx_MODER (address offset 0x00): Mode Register, controls pin mode based on bit configuration.
      • 00: Input mode
      • 01: General purpose output mode
      • 10: Alternate function (AF) mode
      • 11: Analog mode
    • GPIOx_PUPDR (address offset 0x04): Pull-up/Pull-down Register, determines default input level.
      • 00: No pull-up or pull-down
      • 01: Pull-up
      • 10: Pull-down
      • 11: Reserved (do not use)
    • GPIOx_OTYPER (address offset 0x04): Output Type Register, specifies output type.
      • 0: Output push-pull
      • 1: Output open-drain
      • Open-drain mode allows multiple outputs to share a bus by connecting to a single pull-up resistor.

    GPIO Data Registers

    • GPIOx_IDR (address offset 0x10): Input Data Register, read-only, provides current logic level of input pins.
    • GPIOx_ODR (address offset 0x14): Output Data Register, read/write, controls output logic level.
    • GPIOx_BSRR (address offset 0x18): Bit Set/Reset Register, write-only, atomically sets or resets individual output bits.
      • Each bit in this register has two corresponding bits in the output data register (ODR): one to set (BSy) and one to reset (BRy).
    • GPIOx_BRR (address offset 0x28): Bit Reset Register, write-only, resets individual output bits.

    Open-drain Mode

    • Open-drain mode allows bi-directional communication between multiple devices on a single wire.
    • Open-drain mode can be used to interface logic families with different voltage levels.

    GPIO Functions in HAL Library

    • Header file: Drivers/STM32L4xx_HAL_Driver/Inc/stm32l4xx_hal_gpio.h
    • Source file: Drivers/STM32L4xx_HAL_Driver/Src/stm32l4xx_hal_gpio.c

    Interpreting Sensor Output

    • Sensor output values are typically not directly related to the physical quantity being measured.
    • A conversion function, often linear, maps the raw value to the actual magnitude.
    • Many sensors provide 16-bit values as two separate bytes, which must be concatenated to obtain the full value.

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    Related Documents

    EE2028_2410_Lecture 7_Interfacing Concepts and GPIO.pdf

    Description

    Test your knowledge on GPIO control registers, including modes, pull-up/pull-down configurations, and output types. This quiz covers essential concepts and details necessary for understanding how GPIO operates in microcontroller programming.

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