All posts by admin

Arduino Project for a Portable Ultrasonic Distance Sensor

January 30, 2025 admin

In this video lesson we create a portable distance measuring prototype, using an Arduino Uno R4 WiFi. This project incorporates a HC-SR04 Ultrasonic Sensor, a ‘Go’ button, and the SSD1306 OLED Display. The project is powered by the Sunfounder Breadboard power bank. The arduino is powered by the power bank as well, so the project can operate totally portable. When the device is turned on, the OLED prompts the user to position the device. When the ‘Go’ button is pushed, the device measures the distance to the target, then displays the distance on the OLED display.

Schematic of the Portable Arduino Uno R4 WiFi Distance Sensor

The video above gives all the details of the project, with step-by-step instructions.

For your convenience, the code developed in the video is presented below. Enjoy!

#include <SPI.h>
#include <Wire.h>
#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.h>

int butPin = 2;
int butVal = 1;
int butValOld = 1;

int trigPin = 4;
int echoPin = 3;
int pingTime;
float targDist;
int ft;
float in;

int screenWidth = 128;
int screenHeight = 64;
int oledReset = -1;
#define SCREEN_ADDRESS 0x3C
Adafruit_SSD1306 oled(screenWidth, screenHeight, &Wire, oledReset);

void setup() {
  // put your setup code here, to run once:
  Serial.begin(9600);
  pinMode(butPin, INPUT_PULLUP);
  pinMode(trigPin, OUTPUT);
  pinMode(echoPin, INPUT);
  oled.begin(SSD1306_SWITCHCAPVCC, SCREEN_ADDRESS);
  oled.clearDisplay();
  oled.display();
}
void loop() {
  // put your main code here, to run repeatedly:
  oled.setCursor(0, 12);
  oled.setTextColor(WHITE);
  oled.setTextSize(1);
  oled.println("Point the ");
  oled.println("DistoMatic at");
  oled.println("Target and Press");
  oled.println("Go");
  oled.display();
  butVal = digitalRead(butPin);
  if (butValOld == 0 && butVal == 1) {
    targDist = findDistance();
    ft = targDist/12;
    in = targDist - ft*12;
    oled.clearDisplay();
    oled.setCursor(0, 0);
    oled.setTextColor(WHITE);
    oled.setTextSize(2);
    Serial.println(targDist);
    Serial.println(ft);
    Serial.println(in);
    oled.println(String(ft)+" Ft.");
    oled.println(String(in)+" In.");
    oled.display();
    delay(5000);
    oled.clearDisplay();
    oled.display();
  }
  butValOld = butVal;
}

float findDistance() {
  float d;
  digitalWrite(trigPin, LOW);
  delayMicroseconds(2);
  digitalWrite(trigPin, HIGH);
  delayMicroseconds(10);
  digitalWrite(trigPin, LOW);
  d = pulseIn(echoPin, HIGH) / 2. * .0135;
  return d;
}

#include <SPI.h>

#include <Wire.h>

#include <Adafruit_GFX.h>

#include <Adafruit_SSD1306.h>

int butPin = 2;

int butVal = 1;

int butValOld = 1;

int trigPin = 4;

int echoPin = 3;

int pingTime;

float targDist;

int ft;

float in;

int screenWidth = 128;

int screenHeight = 64;

int oledReset = -1;

#define SCREEN_ADDRESS 0x3C

Adafruit_SSD1306 oled(screenWidth, screenHeight, &Wire, oledReset);

void setup() {

// put your setup code here, to run once:

Serial.begin(9600);

pinMode(butPin, INPUT_PULLUP);

pinMode(trigPin, OUTPUT);

pinMode(echoPin, INPUT);

oled.begin(SSD1306_SWITCHCAPVCC, SCREEN_ADDRESS);

oled.clearDisplay();

oled.display();

}

void loop() {

// put your main code here, to run repeatedly:

oled.setCursor(0, 12);

oled.setTextColor(WHITE);

oled.setTextSize(1);

oled.println("Point the ");

oled.println("DistoMatic at");

oled.println("Target and Press");

oled.println("Go");

oled.display();

butVal = digitalRead(butPin);

if (butValOld == 0 && butVal == 1) {

targDist = findDistance();

ft = targDist/12;

in = targDist - ft*12;

oled.clearDisplay();

oled.setCursor(0, 0);

oled.setTextColor(WHITE);

oled.setTextSize(2);

Serial.println(targDist);

Serial.println(ft);

Serial.println(in);

oled.println(String(ft)+" Ft.");

oled.println(String(in)+" In.");

oled.display();

delay(5000);

oled.clearDisplay();

oled.display();

}

butValOld = butVal;

}

float findDistance() {

float d;

digitalWrite(trigPin, LOW);

delayMicroseconds(2);

digitalWrite(trigPin, HIGH);

delayMicroseconds(10);

digitalWrite(trigPin, LOW);

d = pulseIn(echoPin, HIGH) / 2. * .0135;

return d;

}

Raspberry Pi Pico

Measure Distance Using the HC-SR04 Ultrasonic Sensor on the Raspberry Pi Pico

January 28, 2025 admin

In this Video Lesson I will teach you how to use echolocation to measure distances. We will use the HC-SR04 Ultrasonic Sensor, and will use the Raspberry Pi Pico W. We will explain how echolocation works, and show you how the sensor works. We will do the math, and then create the code for making measurements.

import machine
import time

TRIG_PIN = 16
ECHO_PIN = 17

TRIG = machine.Pin(TRIG_PIN,machine.Pin.OUT)
ECHO = machine.Pin(ECHO_PIN,machine.Pin.IN)

def distance():
    TRIG.low()
    time.sleep_us(2)
    TRIG.high()
    time.sleep_us(10)
    TRIG.low()
    while (ECHO.value()==0):
        pass
    time1=time.ticks_us()
    while (ECHO.value()==1):
        pass
    time2=time.ticks_us()
    pingTime=time.ticks_diff(time2,time1)/2
    d=.0343*pingTime
    return d
while True:
    dist=distance()
    print("Distance to Target: ",dist," cm")
    time.sleep_ms(250)

import machine

import time

TRIG_PIN = 16

ECHO_PIN = 17

TRIG = machine.Pin(TRIG_PIN,machine.Pin.OUT)

ECHO = machine.Pin(ECHO_PIN,machine.Pin.IN)

def distance():

TRIG.low()

time.sleep_us(2)

TRIG.high()

time.sleep_us(10)

TRIG.low()

while (ECHO.value()==0):

pass

time1=time.ticks_us()

while (ECHO.value()==1):

pass

time2=time.ticks_us()

pingTime=time.ticks_diff(time2,time1)/2

d=.0343*pingTime

return d

while True:

dist=distance()

print("Distance to Target: ",dist," cm")

time.sleep_ms(250)

Arduino

Using the SSD1306 OLED With an Arduino

January 23, 2025 admin

In this Video Tutorial we show you how to incorporate the SSD1306 OLED into your Arduino project. This is a versatile, low power display that makes it easy for you to incorporate a nice display into your Arduino projects. For this project, we connect the OLED via I2C. The schematic for our project is presented below:

Our physical build looked like this:

The video above shows in depth description of the code development, but for your convenience, we include the code below.

#include <SPI.h>
#include <Wire.h>
#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.h>

int screenWidth = 128;
int screenHeight = 64;
int oledReset = -1;
#define SCREEN_ADDRESS 0x3C
Adafruit_SSD1306 oled(screenWidth,screenHeight,&Wire,oledReset);

void setup() {
  // put your setup code here, to run once:
Serial.begin(9600);
oled.begin(SSD1306_SWITCHCAPVCC, SCREEN_ADDRESS);
}

void loop() {
  // put your main code here, to run repeatedly:
oled.clearDisplay();
oled.display();
oled.setCursor(0,12);
oled.setTextColor(WHITE);
oled.setTextSize(3);
oled.println(" Hello");
oled.println(" World!");
oled.display();
delay(1000);
oled.invertDisplay(1);
delay(1000);
oled.invertDisplay(0);
delay(1000);

oled.clearDisplay();
oled.drawPixel(64,32,WHITE);
oled.display();
delay(1000);

oled.clearDisplay();
oled.drawLine(0,0,127,63,WHITE);
oled.display();
delay(1000);

oled.clearDisplay();
oled.drawLine(0,32,127,32,WHITE);
oled.drawLine(64,0,64,63,WHITE);
oled.display();
delay(1000);

oled.clearDisplay();
oled.drawRect(0,0,128,64,WHITE);
oled.display();
delay(1000);

oled.clearDisplay();
oled.fillRect(0,0,128,64,WHITE);
oled.display();
delay(1000);

oled.clearDisplay();
oled.fillRect(0,0,128,64,WHITE);
oled.fillRect(5,5,118,54,BLACK);
oled.display();
delay(1000);

oled.clearDisplay();
oled.drawCircle(64,32,31,WHITE);
oled.display();
delay(1000);

oled.clearDisplay();
oled.fillCircle(64,32,31,WHITE);
oled.fillCircle(64,32,24,BLACK);
oled.display();
delay(1000);

}

#include <SPI.h>

#include <Wire.h>

#include <Adafruit_GFX.h>

#include <Adafruit_SSD1306.h>

int screenWidth = 128;

int screenHeight = 64;

int oledReset = -1;

#define SCREEN_ADDRESS 0x3C

Adafruit_SSD1306 oled(screenWidth,screenHeight,&Wire,oledReset);

void setup() {

// put your setup code here, to run once:

Serial.begin(9600);

oled.begin(SSD1306_SWITCHCAPVCC, SCREEN_ADDRESS);

}

void loop() {

// put your main code here, to run repeatedly:

oled.clearDisplay();

oled.display();

oled.setCursor(0,12);

oled.setTextColor(WHITE);

oled.setTextSize(3);

oled.println(" Hello");

oled.println(" World!");

oled.display();

delay(1000);

oled.invertDisplay(1);

delay(1000);

oled.invertDisplay(0);

delay(1000);

oled.clearDisplay();

oled.drawPixel(64,32,WHITE);

oled.display();

delay(1000);

oled.clearDisplay();

oled.drawLine(0,0,127,63,WHITE);

oled.display();

delay(1000);

oled.clearDisplay();

oled.drawLine(0,32,127,32,WHITE);

oled.drawLine(64,0,64,63,WHITE);

oled.display();

delay(1000);

oled.clearDisplay();

oled.drawRect(0,0,128,64,WHITE);

oled.display();

delay(1000);

oled.clearDisplay();

oled.fillRect(0,0,128,64,WHITE);

oled.display();

delay(1000);

oled.clearDisplay();

oled.fillRect(0,0,128,64,WHITE);

oled.fillRect(5,5,118,54,BLACK);

oled.display();

delay(1000);

oled.clearDisplay();

oled.drawCircle(64,32,31,WHITE);

oled.display();

delay(1000);

oled.clearDisplay();

oled.fillCircle(64,32,31,WHITE);

oled.fillCircle(64,32,24,BLACK);

oled.display();

delay(1000);

}

Raspberry Pi Pico

Controlling NeoPixel Array on PIO State Machine on Raspberry Pi Pico

January 21, 2025 admin

In this video lesson we show how neopixels work at a fundamental level, and show how you can use the Raspberry Pi Pico State Machines to control the neoixels. Neopixels are an excellent example for showing the importance of the pico state machine. The neopixels demand precise timing and sequence of bits to operate properly, and that precision can not be achieved in python. The video explains how the State Machines can be programmed to control the neopixels.

For your convenience, the code is included below.

import rp2
from machine import Pin
import time
@rp2.asm_pio(sideset_init=rp2.PIO.OUT_HIGH,
             out_shiftdir=rp2.PIO.SHIFT_LEFT,
             autopull=True,
             pull_thresh=24)
def ws2812():
    wrap_target()
    label("bitloop")
    out(x,1).side(0)
    jmp(not_x,"do_zero").side(1)
    nop().side(1)[5-1]
    nop().side(0)[2-1]
    jmp("bitloop").side(0)
    label("do_zero")
    nop().side(1)[2-1]
    jmp("bitloop").side(0)[6-1]
    wrap()
sm=rp2.StateMachine(0,ws2812,freq=8000000,sideset_base=Pin(0))
sm.active(1)

def write_neopixel(colors):
    for color in colors:
        grb=color[1]<<16 | color[0]<<8 | color[2]
        sm.put(grb,8)
        
    
NUM_LEDS =8
myColor=[0]*NUM_LEDS
myColor=[[100,0,0],
         [0,100,0],
         [0,0,100],
         [0,100,100],
         [100,0,100],
         [100,100,0],
         [200,100,0],
         [255,255,255]]
write_neopixel(myColor)

import rp2

from machine import Pin

import time

@rp2.asm_pio(sideset_init=rp2.PIO.OUT_HIGH,

out_shiftdir=rp2.PIO.SHIFT_LEFT,

autopull=True,

pull_thresh=24)

def ws2812():

wrap_target()

label("bitloop")

out(x,1).side(0)

jmp(not_x,"do_zero").side(1)

nop().side(1)[5-1]

nop().side(0)[2-1]

jmp("bitloop").side(0)

label("do_zero")

nop().side(1)[2-1]

jmp("bitloop").side(0)[6-1]

wrap()

sm=rp2.StateMachine(0,ws2812,freq=8000000,sideset_base=Pin(0))

sm.active(1)

def write_neopixel(colors):

for color in colors:

grb=color[1]<<16 | color[0]<<8 | color[2]

sm.put(grb,8)

NUM_LEDS =8

myColor=[0]*NUM_LEDS

myColor=[[100,0,0],

[0,100,0],

[0,0,100],

[0,100,100],

[100,0,100],

[100,100,0],

[200,100,0],

[255,255,255]]

write_neopixel(myColor)

Raspberry Pi Pico

Raspberry Pi Pico PIO State Machine IRQ Interrupts and Handlers

January 14, 2025 admin

In this video lesson we learn how to use and handle multiple IRQ interrupts using the Raspberry Pi Pico PIO state machines. We demonstrate this by using 3 LEDs, controlled by three separate buttons. We show how to set, clear, and wait on IRQ interrupts. We show how to use blocking and no blocking interrupts. In this video lesson, we use the following circuit.

For your convenience, the code we develop in the video is presented below.

import rp2
from machine import Pin
import time

# Define PIO program for the button to trigger an interrupt on SM0
@rp2.asm_pio()
def button_irq():
    wrap_target()
    label('readAgain')
    mov(isr,null) [31]
    in_(pins,3) [31]
    mov(x,isr) [31]
    jmp(not_x,'readAgain')
    set(y,0b001);
    jmp(x_not_y,'checkYellow')
    irq(block,0)
    wait(0,pin,0)
    jmp('readAgain')
    label('checkYellow')
    set(y,0b010)
    jmp(x_not_y,'checkRed')
    irq(block,1)
    wait(0,pin,1)
    jmp('readAgain')
    label('checkRed') 
    irq(block,2)
    wait(0,pin,2)
    wrap()

# Define PIO program for the LED control on SM1
@rp2.asm_pio(out_init=rp2.PIO.OUT_LOW)
def led_control1():
    set(x, 0b00000)         # Initialize X register to 0 (LED off initially)
    wrap_target()
    wait(1, irq, 0)   # Wait for interrupt 0 to be set
    mov(x, invert(x)) # Invert X register to toggle state
    mov(pins,x)
    irq(clear, 0)     # Clear the interrupt to allow the next press to be handled
    wrap()
@rp2.asm_pio(out_init=rp2.PIO.OUT_LOW)
def led_control2():
    set(x, 0b00000)         # Initialize X register to 0 (LED off initially)
    wrap_target()
    wait(1, irq, 1)   # Wait for interrupt 0 to be set
    mov(x, invert(x)) # Invert X register to toggle state
    mov(pins,x)
    irq(clear, 1)     # Clear the interrupt to allow the next press to be handled
    wrap()
@rp2.asm_pio(out_init=rp2.PIO.OUT_LOW)
def led_control3():
    set(x, 0b00000)         # Initialize X register to 0 (LED off initially)
    wrap_target()
    wait(1, irq, 2)   # Wait for interrupt 0 to be set
    mov(x, invert(x)) # Invert X register to toggle state
    mov(pins,x)
    irq(clear, 2)     # Clear the interrupt to allow the next press to be handled
    wrap()

# Initialize State Machine 0 for the button (GPIO 11)
button_pin = Pin(11, Pin.IN, Pin.PULL_DOWN)
button_pin2 = Pin(12, Pin.IN, Pin.PULL_DOWN)
button_pin3 = Pin(13, Pin.IN, Pin.PULL_DOWN)
sm_button = rp2.StateMachine(0, button_irq, freq=2000, in_base=button_pin)

# Initialize State Machine 1 for the LED (GPIO 18)
led_pin1 = Pin(18, Pin.OUT)
sm_led1 = rp2.StateMachine(1, led_control1, freq=2000, out_base=led_pin1)
# 
led_pin2 = Pin(19, Pin.OUT)
sm_led2 = rp2.StateMachine(2, led_control2, freq=2000, out_base=led_pin2)

led_pin3 = Pin(20, Pin.OUT)
sm_led3 = rp2.StateMachine(3, led_control3, freq=2000, out_base=led_pin3)
# 
# Activate both state machines
sm_button.active(1)
sm_led1.active(1)
sm_led2.active(1)
sm_led3.active(1)
# Keep the program running

import rp2

from machine import Pin

import time

# Define PIO program for the button to trigger an interrupt on SM0

@rp2.asm_pio()

def button_irq():

wrap_target()

label('readAgain')

mov(isr,null) [31]

in_(pins,3) [31]

mov(x,isr) [31]

jmp(not_x,'readAgain')

set(y,0b001);

jmp(x_not_y,'checkYellow')

irq(block,0)

wait(0,pin,0)

jmp('readAgain')

label('checkYellow')

set(y,0b010)

jmp(x_not_y,'checkRed')

irq(block,1)

wait(0,pin,1)

jmp('readAgain')

label('checkRed')

irq(block,2)

wait(0,pin,2)

wrap()

# Define PIO program for the LED control on SM1

@rp2.asm_pio(out_init=rp2.PIO.OUT_LOW)

def led_control1():

set(x, 0b00000) # Initialize X register to 0 (LED off initially)

wrap_target()

wait(1, irq, 0) # Wait for interrupt 0 to be set

mov(x, invert(x)) # Invert X register to toggle state

mov(pins,x)

irq(clear, 0) # Clear the interrupt to allow the next press to be handled

wrap()

@rp2.asm_pio(out_init=rp2.PIO.OUT_LOW)

def led_control2():

set(x, 0b00000) # Initialize X register to 0 (LED off initially)

wrap_target()

wait(1, irq, 1) # Wait for interrupt 0 to be set

mov(x, invert(x)) # Invert X register to toggle state

mov(pins,x)

irq(clear, 1) # Clear the interrupt to allow the next press to be handled

wrap()

@rp2.asm_pio(out_init=rp2.PIO.OUT_LOW)

def led_control3():

set(x, 0b00000) # Initialize X register to 0 (LED off initially)

wrap_target()

wait(1, irq, 2) # Wait for interrupt 0 to be set

mov(x, invert(x)) # Invert X register to toggle state

mov(pins,x)

irq(clear, 2) # Clear the interrupt to allow the next press to be handled

wrap()

# Initialize State Machine 0 for the button (GPIO 11)

button_pin = Pin(11, Pin.IN, Pin.PULL_DOWN)

button_pin2 = Pin(12, Pin.IN, Pin.PULL_DOWN)

button_pin3 = Pin(13, Pin.IN, Pin.PULL_DOWN)

sm_button = rp2.StateMachine(0, button_irq, freq=2000, in_base=button_pin)

# Initialize State Machine 1 for the LED (GPIO 18)

led_pin1 = Pin(18, Pin.OUT)

sm_led1 = rp2.StateMachine(1, led_control1, freq=2000, out_base=led_pin1)

led_pin2 = Pin(19, Pin.OUT)

sm_led2 = rp2.StateMachine(2, led_control2, freq=2000, out_base=led_pin2)

led_pin3 = Pin(20, Pin.OUT)

sm_led3 = rp2.StateMachine(3, led_control3, freq=2000, out_base=led_pin3)

# Activate both state machines

sm_button.active(1)

sm_led1.active(1)

sm_led2.active(1)

sm_led3.active(1)

# Keep the program running

Technology Tutorials

All posts by admin

Arduino Project for a Portable Ultrasonic Distance Sensor

Measure Distance Using the HC-SR04 Ultrasonic Sensor on the Raspberry Pi Pico

Using the SSD1306 OLED With an Arduino

Controlling NeoPixel Array on PIO State Machine on Raspberry Pi Pico

Raspberry Pi Pico PIO State Machine IRQ Interrupts and Handlers

Making The World a Better Place One High Tech Project at a Time. Enjoy!