ECEN 421 Quizzes (5-8)

5) How many pins of the DHT11 sensor need to be connected to circuitry in order for it to operate correctly?

3

5) How many data pins are needed on a single device for I2C Communications?

2

5) For the Homework 5 assignment, what code change had to made without xTaskCreate?

Directly calling the function with no arguments

5) Write a segment of code that you would use to display the sentence “hello world” on the bottom row of the LCD 1602

string = “Hello World”;

sprintf(strl”%s”,string);

LCD(strl)

char buff(17)

memset(buff, 0, sizeof(buff));

sprintf(buff, “Hello World”);

LCD_set cursor(0,1);

LCD_writestr(buff);

6) What is the unit for the amount of time specified by the second input parameter for the ESP-IDE function?

microseconds

6) Which ESP-IDF function is used to give a name to a GPIO interrupt service routine?

gpio_isr_handler_add

6) How many pins of the LCD1602 device are used for data communication?

1

6) Assume that one terminal of a normally-closed push-button is connected to GPIO27 of the ESP32, while the other terminal is connected to Vcc. Write the segment of code that will allow the press of this button to generate an interrupt on the ESP32

esp_rom_gipo_pad_select_gipo(27);

gipo_set_direction(27, GPIO_MODE_INPUT);

gipo_pulldown_en(27);

gipo_pullup_dis(27);

gipo_set_intr_type(27, GPIO_INTR_NEGEDGE);

gipo_install_isr_service(0);

gipo_isr_handler_add(27,gipo_ISR,NULL);

7) What basic electrical property does the ESP32 touch sensor rely on?

Capacitance

7) For the concurrent state machines in HW 7, which of the following was used for communication between the two state machines?

Global Variable

7) The technique of using sleep modes in an embedded systems program is an example of what type of optimization?

Power

8) In an ESP IDR program, what instructions should replace the following instruction in order to create the same amount of delay while in light sleep mode?

esp_sleep_enable_time_wakeup(200000); //in 20000 microseconds = 20 milliseccond esp_light_sleep_start();

8) In FreeRTOS, a task has to be contained with what type loop?

Infinite loop

8) Which of the following RTOS objects is used to protect a critical section of a program?

Mutex

8) What type of access does a queue data structure have?

FIFO

8) Draw the diagram of a circuit that will allow for a photoresistor to provide a Logic 0 value for an input pin when it is not exposed to any light