Lab 14 ADC with LCD

Objective:

• The objective of this lab is to utilize the ADC peripheral alongside the LCD driver to create a digital multimeter (DMM). The LCD driver was provided by the main author of this documentation, Jesus Minjares, the driver can be found here: LCD Driver.

Bonus

• Undergrad Bonus:
  • Use the digital multimeter to read a simple voltage-divider circuit.
• Grad Bonus:
  • Using the ADC readings control the sweeper function from previous labs. Use up to 6 LEDs to demonstrate it. When the ADC reads the lowest value the LSB LED must turn on and when the ADC reads the highest value the MSB LED must turn on.

ESP32 Pinout

                                        +-----------------------+
                                        | O      | USB |      O |
                                        |        -------        |
                                    3V3 | [ ]               [ ] | VIN
                                    GND | [ ]               [ ] | GND
    Touch3 / HSPI_CS0 / ADC2_3 / GPIO15 | [ ]               [ ] | GPIO13 / ADC2_4 / HSPI_ID / Touch4
CS / Touch2 / HSPI_WP / ADC2_2 /  GPIO2 | [ ]               [ ] | GPIO12 / ADC2_5 / HSPI_Q / Touch5
     Touch0 / HSPI_HD / ADC2_0 /  GPIO4 | [ ]               [ ] | GPIO14 / ADC2_6 / HSPI_CLK / Touch6
                        U2_RXD / GPIO16 | [ ]               [ ] | GPIO27 / ADC2_7 / Touch7
                        U2_TXD / GPIO17 | [ ]               [ ] | GPIO26 / ADC2_9 / DAC2
                     V_SPI_CS0 /  GPIO5 | [ ]  ___________  [ ] | GPIO25 / ADC2_8 / DAC1
               SCK / V_SPI_CLK / GPIO18 | [ ] |           | [ ] | GPIO33 / ADC1_5 / Touch8 / XTAL32
       U0_CTS / MSIO / V_SPI_Q / GPIO19 | [ ] |           | [ ] | GPIO32 / ADC1_4 / Touch9 / XTAL32
                SDA / V_SPI_HD / GPIO21 | [ ] |           | [ ] | GPIO35 / ADC1_7 
                 CLK2 / U0_RXD /  GPIO3 | [ ] |           | [ ] | GPIO34 / ADC1_6 
                 CLK3 / U0_TXD /  GPIO1 | [ ] |           | [ ] | GPIO39 / ADC1_3 / SensVN 
       SCL / U0_RTS / V_SPI_WP / GPIO22 | [ ] |           | [ ] | GPIO36 / ADC1_0 / SensVP 
               MOSI / V_SPI_WP / GPIO23 | [ ] |___________| [ ] | EN 
                                        |                       |
                                        |  |  |  ____  ____  |  |
                                        |  |  |  |  |  |  |  |  |
                                        |  |__|__|  |__|  |__|  |
                                        | O                   O |
                                        +-----------------------+

LCD Example Code

This is an example code that demostrates how to utilize the LCD driver.

#include <stdio.h>
#include "freertos/FreeRTOS.h"
#include "freertos/task.h"
#include "driver/esp_lcd.h"
/* LCD task */
void lcd_task(void *pvParameters){
    /* Create LCD object */
    lcd_t lcd;
    /* Set LCD to default pins */
    lcdDefault(&lcd);
    /* Initialize LCD object */
    lcdInit(&lcd);
    /* Clear previous data on LCD */
    lcdClear(&lcd);
 
    while(1){
        /* Display Text */
        lcdSetText(&lcd, "Hello World!", 0, 0);
        /* 1 second delay */
        vTaskDelay(1000 / portTICK_PERIOD_MS);
    }
}
void app_main(void){
    /* Create LCD Task */
    xTaskCreate(lcd_task, "LCD Task", 2048, NULL, 4, NULL);
}

Lab Template

#include <stdio.h>
#include "freertos/FreeRTOS.h"
#include "freertos/task.h"
#include "driver/esp_lcd.h"
/* Create Function to covert ADC Value to Voltage */
 
/* Create Function for ADC initialization */
void ADC_setup(void){
 
}
/* Create Function for PWM Initialization */
void PWM_setup(void){
 
}
/* Function for sweeper */
void sweeper_function(uint32_t val){
 
}
/* LCD task */
void lcd_task(void *pvParameters){
    /* Setup LCD */
    
    while(1){
        /* Get ADC Raw Readings */
 
        /* Get Conversion */
 
        /* Display Voltage onto LCD */
 
        /* Change PWM output to match ADC readings */
 
    }
}
void app_main(void){
    /* Create LCD Task */
    
}

Warning

Before anything you must add the library for the LCD driver onto the CMakeLists.txt which is found in the lab's main folder. This would be how to add it:

idf_component_register(SRCS "main.c"
                            "driver/esp_lcd.c"
                    INCLUDE_DIRS ".")

Author:

• Jorge Minjares
  
  • Bachelor of Science in Electrical Engineering