Tag Archives: LED

RFID Project to Lock and Unlock Control of Servo

May 20, 2025 admin

In this video lesson we explore a project where control access to a servo is activated by an RDID tag. In order to position the servo with the pushbuttons, the system must be unlocked by a RDID tag. When the system is locked, the LED is red, when the system is unlocked, the LED is green. When using the breadvolt, or any battery power supply on a breadboard project, do not turn the power supply on while the Raspberry Pi Pico is connected to USB, as you could generate voltage conflicts. It is an either or. If the USB is connected, the power supply should be OFF. Or if you are going to connect the USB, first turn off the power supply.

RFID-SERVO — This schematic allows servo control to be granted via RFID tag

For your convenience, this is the code we developed below.

# ====================================================================
# DISCLAIMER:
# This code is provided as-is for educational and experimental 
# purposes only. The author makes no representations or warranties of 
# any kind concerning the safety, suitability, or accuracy of this 
# code. Use at your own risk. The author assumes no liability for any 
# damages, system failures, security breaches, or network issues 
# resulting from the use or implementation of this script.
# ====================================================================

from mfrc522 import SimpleMFRC522
import time
import ujson
from machine import Pin, PWM
unlockTime = 5
decPin = 20
incPin = 21
servoPin=0
decBut=Pin(decPin,Pin.IN,Pin.PULL_UP)
incBut=Pin(incPin,Pin.IN,Pin.PULL_UP)

redPin=15
greenPin=14
bluePin=13
redLED=Pin(redPin,Pin.OUT)
greenLED=Pin(greenPin,Pin.OUT)
blueLED=Pin(bluePin,Pin.OUT)
redLED.on()
greenLED.off()
blueLED.off()

incButState=1
incButStateOld=1

decButState=1
decButStateOld=1

myServo=PWM(Pin(servoPin))
myServo.freq(50)
servoAngle=0

reader=SimpleMFRC522(spi_id=0,sck=18,miso=16,mosi=19,cs=17,rst=9)

try:
    f=open("/dict.json","r")
    servoDict=ujson.load(f)
    f.close()
except:
    myDict={}
    f=open('dict.json','w')
    ujson.dump(myDict,f)
    f.close()
def readRFID():
    global cardID,servoAngle
    print()
    print("System LOCKED")
    print("Reading . . . Please Place the Card")
    cardID,readText = reader.read()
    print()
    print("ID: ",cardID)
    try:
        f=open('/dict.json','r')
        servoDict = ujson.load(f)
        f.close()
        servoAngle=servoDict[cardID]
        print(servoAngle)
        moveServo()
    except:
        f=open('/dict.json','r')
        myDict=ujson.load(f)
        f.close()
        myDict[cardID]=servoAngle
        f = open('/dict.json','w')
        ujson.dump(myDict,f)
        f.close()
        moveServo()

def moveServo():
    writeVal = 6553/180*servoAngle + 1638
    myServo.duty_u16(int(writeVal))
    f=open('/dict.json','r')
    myDict =ujson.load(f)
    f.close()
    myDict[cardID]=servoAngle
    f=open('/dict.json','w')
    ujson.dump(myDict, f)
    f.close()
while True:
    redLED.on()
    greenLED.off()
    blueLED.off()
    readRFID()
    print("System Unlocked by Card: ",cardID)
    unlockStart= time.time()
    while time.time()-unlockStart<unlockTime:
        redLED.off()
        greenLED.on()
        incButState=incBut.value()
        decButState=decBut.value()
        if incButState==0 and incButStateOld==1:
            servoAngle=servoAngle + 10
            if servoAngle>180:
                servoAngle=180
            if servoAngle<0:
                servoAngle=0
            moveServo()
            unlockStart=time.time()
            ts=.2
            time.sleep(ts)
        if decButState==0 and decButStateOld==1:
            servoAngle=servoAngle - 10
            if servoAngle>180:
                servoAngle=180
            if servoAngle<0:
                servoAngle=0
            moveServo()
            unlockStart=time.time()
            ts=.2
            time.sleep(.2)
        incButStateOld=incButState
        decButStateOld=decButState

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# ====================================================================

# DISCLAIMER:

# This code is provided as-is for educational and experimental

# purposes only. The author makes no representations or warranties of

# any kind concerning the safety, suitability, or accuracy of this

# code. Use at your own risk. The author assumes no liability for any

# damages, system failures, security breaches, or network issues

# resulting from the use or implementation of this script.

# ====================================================================

from mfrc522 import SimpleMFRC522

import time

import ujson

from machine import Pin, PWM

unlockTime = 5

decPin = 20

incPin = 21

servoPin=0

decBut=Pin(decPin,Pin.IN,Pin.PULL_UP)

incBut=Pin(incPin,Pin.IN,Pin.PULL_UP)

redPin=15

greenPin=14

bluePin=13

redLED=Pin(redPin,Pin.OUT)

greenLED=Pin(greenPin,Pin.OUT)

blueLED=Pin(bluePin,Pin.OUT)

redLED.on()

greenLED.off()

blueLED.off()

incButState=1

incButStateOld=1

decButState=1

decButStateOld=1

myServo=PWM(Pin(servoPin))

myServo.freq(50)

servoAngle=0

reader=SimpleMFRC522(spi_id=0,sck=18,miso=16,mosi=19,cs=17,rst=9)

try:

f=open("/dict.json","r")

servoDict=ujson.load(f)

f.close()

except:

myDict={}

f=open('dict.json','w')

ujson.dump(myDict,f)

f.close()

def readRFID():

global cardID,servoAngle

print()

print("System LOCKED")

print("Reading . . . Please Place the Card")

cardID,readText = reader.read()

print()

print("ID: ",cardID)

try:

f=open('/dict.json','r')

servoDict = ujson.load(f)

f.close()

servoAngle=servoDict[cardID]

print(servoAngle)

moveServo()

except:

f=open('/dict.json','r')

myDict=ujson.load(f)

f.close()

myDict[cardID]=servoAngle

f = open('/dict.json','w')

ujson.dump(myDict,f)

f.close()

moveServo()

def moveServo():

writeVal = 6553/180*servoAngle + 1638

myServo.duty_u16(int(writeVal))

f=open('/dict.json','r')

myDict =ujson.load(f)

f.close()

myDict[cardID]=servoAngle

f=open('/dict.json','w')

ujson.dump(myDict, f)

f.close()

while True:

redLED.on()

greenLED.off()

blueLED.off()

readRFID()

print("System Unlocked by Card: ",cardID)

unlockStart= time.time()

while time.time()-unlockStart<unlockTime:

redLED.off()

greenLED.on()

incButState=incBut.value()

decButState=decBut.value()

if incButState==0 and incButStateOld==1:

servoAngle=servoAngle + 10

if servoAngle>180:

servoAngle=180

if servoAngle<0:

servoAngle=0

moveServo()

unlockStart=time.time()

ts=.2

time.sleep(ts)

if decButState==0 and decButStateOld==1:

servoAngle=servoAngle - 10

if servoAngle>180:

servoAngle=180

if servoAngle<0:

servoAngle=0

moveServo()

unlockStart=time.time()

ts=.2

time.sleep(.2)

incButStateOld=incButState

decButStateOld=decButState

Python, Raspberry Pi Pico

Simple Client Server Project for the Raspberry Pi Pico W

February 25, 2025 admin

In this video lesson we demonstrate a simple client server project on the Raspberry Pi Pico W. The Pico is configures as the server, and your desktop pc or laptop is configures to be the client. You will be running python on your PC. The project requests the user on the PC to specify a desired color. The color is then sent to the Pico, the Server.

For this lesson we are not using the breadvolt power supply, but we will use it in future lessons. For this lesson, you do not need to attach it, and if you do attach it, leave it ‘off’.

Below is the schematic for the Server Side of the project:

LED and Buttons — Schematic for Circuit to Demonstrate a Client Server Example on Pi Pico

For your convenience, this is the code we developed in the video

# ====================================================================
# DISCLAIMER:
# This code is provided as-is for educational and experimental 
# purposes only. The author makes no representations or warranties of 
# any kind concerning the safety, suitability, or accuracy of this 
# code. Use at your own risk. The author assumes no liability for any 
# damages, system failures, security breaches, or network issues 
# resulting from the use or implementation of this script.
# ====================================================================

import network
import usocket as socket
import secrets
import time

greenLED=machine.Pin(18,machine.Pin.OUT)
yellowLED=machine.Pin(19,machine.Pin.OUT)
redLED=machine.Pin(20,machine.Pin.OUT)
# Set up WiFi connection
wlan = network.WLAN(network.STA_IF)
wlan.active(True)
print(secrets.SSID,secrets.PASSWORD)
wlan.connect(secrets.SSID,secrets.PASSWORD)

# Wait for connection
ts=1
while not wlan.isconnected():
    time.sleep(ts)
print("Connection Completed")
print('WiFi connected')
print(wlan.ifconfig())

# Set up UDP server
server_socket = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
server_socket.bind((wlan.ifconfig()[0], 12345))
print("Server is Up and Listening")
print(wlan.ifconfig()[0])

while True:
    print('Waiting for a request from the client...')
    # Receive request from client
    color, client_address = server_socket.recvfrom(1024)
    color=color.decode()
    print("Client Request:",color)
    print("FROM CLIENT",client_address)
    
    if (color=="green"):
        greenLED.on()
        yellowLED.off()
        redLED.off()
    if (color=="yellow"):
        greenLED.off()
        yellowLED.on()
        redLED.off()
    if (color=="red"):
        greenLED.off()
        yellowLED.off()
        redLED.on()
    if (color=="off"):
        greenLED.off()
        yellowLED.off()
        redLED.off()
    
    # Send data to client
    data="LED "+color+" executed"
    server_socket.sendto(data.encode(), client_address)
    print(f'Sent data to {client_address}')
    
    # Optional: Pause for a short period to prevent overwhelming the client
    time.sleep(ts)

# ====================================================================

# DISCLAIMER:

# This code is provided as-is for educational and experimental

# purposes only. The author makes no representations or warranties of

# any kind concerning the safety, suitability, or accuracy of this

# code. Use at your own risk. The author assumes no liability for any

# damages, system failures, security breaches, or network issues

# resulting from the use or implementation of this script.

# ====================================================================

import network

import usocket as socket

import secrets

import time

greenLED=machine.Pin(18,machine.Pin.OUT)

yellowLED=machine.Pin(19,machine.Pin.OUT)

redLED=machine.Pin(20,machine.Pin.OUT)

# Set up WiFi connection

wlan = network.WLAN(network.STA_IF)

wlan.active(True)

print(secrets.SSID,secrets.PASSWORD)

wlan.connect(secrets.SSID,secrets.PASSWORD)

# Wait for connection

ts=1

while not wlan.isconnected():

time.sleep(ts)

print("Connection Completed")

print('WiFi connected')

print(wlan.ifconfig())

# Set up UDP server

server_socket = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)

server_socket.bind((wlan.ifconfig()[0], 12345))

print("Server is Up and Listening")

print(wlan.ifconfig()[0])

while True:

print('Waiting for a request from the client...')

# Receive request from client

color, client_address = server_socket.recvfrom(1024)

color=color.decode()

print("Client Request:",color)

print("FROM CLIENT",client_address)

if (color=="green"):

greenLED.on()

yellowLED.off()

redLED.off()

if (color=="yellow"):

greenLED.off()

yellowLED.on()

redLED.off()

if (color=="red"):

greenLED.off()

yellowLED.off()

redLED.on()

if (color=="off"):

greenLED.off()

yellowLED.off()

redLED.off()

# Send data to client

data="LED "+color+" executed"

server_socket.sendto(data.encode(), client_address)

print(f'Sent data to {client_address}')

# Optional: Pause for a short period to prevent overwhelming the client

time.sleep(ts)

Remember you must create a secrets.py file, and save it on the Pi Pico in the lib folder. You need to specify YOUR WiFi name and password in the file.

SSID="YOUR WIFI NAME"
PASSWORD="YOUR WIFI PASSWORD"

1 2	SSID="YOUR WIFI NAME" PASSWORD="YOUR WIFI PASSWORD"

And finally, here is the code to run on the client side on your PC

# ====================================================================
# DISCLAIMER:
# This code is provided as-is for educational and experimental 
# purposes only. The author makes no representations or warranties of 
# any kind concerning the safety, suitability, or accuracy of this 
# code. Use at your own risk. The author assumes no liability for any 
# damages, system failures, security breaches, or network issues 
# resulting from the use or implementation of this script.
# ====================================================================

import socket
import time

# Set up UDP client
client_socket = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
server_address = ('192.168.88.71', 12345)  # Adjust IP address and port as needed

while True:
    # Send request to the server
    myColor=input("Please Input Your Color (Green, Yellow, Red, Off )")
    myColor=myColor.lower()
    client_socket.sendto(myColor.encode(), server_address)
    
    # Receive data from the server
    data, addr = client_socket.recvfrom(1024)
    print('Received data:', data.decode())

# ====================================================================

# DISCLAIMER:

# This code is provided as-is for educational and experimental

# purposes only. The author makes no representations or warranties of

# any kind concerning the safety, suitability, or accuracy of this

# code. Use at your own risk. The author assumes no liability for any

# damages, system failures, security breaches, or network issues

# resulting from the use or implementation of this script.

# ====================================================================

import socket

import time

# Set up UDP client

client_socket = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)

server_address = ('192.168.88.71', 12345) # Adjust IP address and port as needed

while True:

# Send request to the server

myColor=input("Please Input Your Color (Green, Yellow, Red, Off )")

myColor=myColor.lower()

client_socket.sendto(myColor.encode(), server_address)

# Receive data from the server

data, addr = client_socket.recvfrom(1024)

print('Received data:', data.decode())

Arduino

Create a Bouncing Pixel on the Arduino Uno R4 WiFi LED Matrix

August 8, 2024 admin

In this video lesson we create a bouncing pixel on the Arduino Uno R4 LED Matrix. For your convenience we include the code developed in the video below.

#include "Arduino_LED_Matrix.h"
ArduinoLEDMatrix matrix;

int br=115200;
int dt=50;
int xPos=3;
int yPos=2;
int deltaX=1;
int deltaY=1;

int i;
int j;

byte frame[8][12];

void setup() {
  // put your setup code here, to run once:
Serial.begin(br);
matrix.begin();
}
void loop() {
  // put your main code here, to run repeatedly:
for ( i=0;i<=11;i=i+1){
  for (j=0;j<=7;j=j+1){
    frame[j][i]=0;
    if (i==xPos && j==yPos){
      frame[j][i]=1;
    }
  }
}
matrix.renderBitmap(frame,8,12);
if (xPos>=11 || xPos<=0){
  deltaX=-deltaX;
}
if (yPos>=7 || yPos<=0){
  deltaY=-deltaY;
}
xPos=xPos+deltaX;
yPos=yPos+deltaY;
delay(dt);
}

#include "Arduino_LED_Matrix.h"

ArduinoLEDMatrix matrix;

int br=115200;

int dt=50;

int xPos=3;

int yPos=2;

int deltaX=1;

int deltaY=1;

int i;

int j;

byte frame[8][12];

void setup() {

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

Serial.begin(br);

matrix.begin();

}

void loop() {

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

for ( i=0;i<=11;i=i+1){

for (j=0;j<=7;j=j+1){

frame[j][i]=0;

if (i==xPos && j==yPos){

frame[j][i]=1;

}

matrix.renderBitmap(frame,8,12);

if (xPos>=11 || xPos<=0){

deltaX=-deltaX;

}

if (yPos>=7 || yPos<=0){

deltaY=-deltaY;

}

xPos=xPos+deltaX;

yPos=yPos+deltaY;

delay(dt);

}

MicroPython, Raspberry Pi Pico

MicroPython MultiCore Programming on the Raspberry Pi Pico Using Threading

May 7, 2024 admin

In this video I show how to use both cores on the Raspberry Pi Pico W. We will explore an example using threading where we will operate 2 LED and a servo.

# ====================================================================
# DISCLAIMER:
# This code is provided as-is for educational and experimental 
# purposes only. The author makes no representations or warranties of 
# any kind concerning the safety, suitability, or accuracy of this 
# code. Use at your own risk. The author assumes no liability for any 
# damages, system failures, security breaches, or network issues 
# resulting from the use or implementation of this script.
# ====================================================================

from machine import Pin
import time
import _thread
import SERVO

greenPin=14
redPin=15
servoPin=17

LED=""

redLED=Pin(redPin,Pin.OUT)
greenLED=Pin(greenPin,Pin.OUT)

delOn=.1
delOff=.1
myServo=SERVO.servo(servoPin)
running =True

def othCore(del1,del2):
    global LED
    while True:
        if LED=="RED":
            redLED.value(1)
            time.sleep(del1)
            redLED.value(0)
            time.sleep(del2)
        if LED=="GREEN":
            greenLED.value(1)
            time.sleep(del1)
            greenLED.value(0)
            time.sleep(del2)
_thread.start_new_thread(othCore,(delOn,delOff))
ts=.25
time.sleep(ts)
ts=.01
while True:
    LED="RED"
    for i in range(0,180,1):
        myServo.pos(i)
        time.sleep(ts)
    LED="GREEN"
    for i in range(180,0,-1):
        myServo.pos(i)
        time.sleep(ts)

# ====================================================================

# DISCLAIMER:

# This code is provided as-is for educational and experimental

# purposes only. The author makes no representations or warranties of

# any kind concerning the safety, suitability, or accuracy of this

# code. Use at your own risk. The author assumes no liability for any

# damages, system failures, security breaches, or network issues

# resulting from the use or implementation of this script.

# ====================================================================

from machine import Pin

import time

import _thread

import SERVO

greenPin=14

redPin=15

servoPin=17

LED=""

redLED=Pin(redPin,Pin.OUT)

greenLED=Pin(greenPin,Pin.OUT)

delOn=.1

delOff=.1

myServo=SERVO.servo(servoPin)

running =True

def othCore(del1,del2):

global LED

while True:

if LED=="RED":

redLED.value(1)

time.sleep(del1)

redLED.value(0)

time.sleep(del2)

if LED=="GREEN":

greenLED.value(1)

time.sleep(del1)

greenLED.value(0)

time.sleep(del2)

_thread.start_new_thread(othCore,(delOn,delOff))

ts=.25

time.sleep(ts)

ts=.01

while True:

LED="RED"

for i in range(0,180,1):

myServo.pos(i)

time.sleep(ts)

LED="GREEN"

for i in range(180,0,-1):

myServo.pos(i)

time.sleep(ts)

Raspberry Pi

Create a Dimmable LED with a Potentiometer on the Raspberry Pi

June 23, 2022 admin

In this video lesson, we show how to create a dimmable LED on the raspberry pi using a potentiometer. Below is the schematic of the circuit we will be using.

Then we used the following code to read values through the ADC0834 analog to digital chip, and then apply a PWM signal to control the brightness of the LED.

# ====================================================================
# DISCLAIMER:
# This code is provided as-is for educational and experimental 
# purposes only. The author makes no representations or warranties of 
# any kind concerning the safety, suitability, or accuracy of this 
# code. Use at your own risk. The author assumes no liability for any 
# damages, system failures, security breaches, or network issues 
# resulting from the use or implementation of this script.
# ====================================================================
 
import RPi.GPIO as GPIO
import ADC0834
import time

GPIO.setmode(GPIO.BCM)

LEDPin=23
GPIO.setup(LEDPin,GPIO.OUT)
myPWM=GPIO.PWM(LEDPin,1000)
myPWM.start(0)
ADC0834.setup()
try:
    while True:
        analogVal=ADC0834.getResult(0)
        print('Raw= ',analogVal, 'Vol= ', analogVal/255*5)
        DC=analogVal*100/255
        myPWM.ChangeDutyCycle(DC)
        time.sleep(.2)
        
except KeyboardInterrupt:
    GPIO.cleanup()
    print('GPIO Good to Go')

# ====================================================================

# DISCLAIMER:

# This code is provided as-is for educational and experimental

# purposes only. The author makes no representations or warranties of

# any kind concerning the safety, suitability, or accuracy of this

# code. Use at your own risk. The author assumes no liability for any

# damages, system failures, security breaches, or network issues

# resulting from the use or implementation of this script.

# ====================================================================

import RPi.GPIO as GPIO

import ADC0834

import time

GPIO.setmode(GPIO.BCM)

LEDPin=23

GPIO.setup(LEDPin,GPIO.OUT)

myPWM=GPIO.PWM(LEDPin,1000)

myPWM.start(0)

ADC0834.setup()

try:

while True:

analogVal=ADC0834.getResult(0)

print('Raw= ',analogVal, 'Vol= ', analogVal/255*5)

DC=analogVal*100/255

myPWM.ChangeDutyCycle(DC)

time.sleep(.2)

except KeyboardInterrupt:

GPIO.cleanup()

print('GPIO Good to Go')

Technology Tutorials

Tag Archives: LED

RFID Project to Lock and Unlock Control of Servo

Simple Client Server Project for the Raspberry Pi Pico W

Create a Bouncing Pixel on the Arduino Uno R4 WiFi LED Matrix

MicroPython MultiCore Programming on the Raspberry Pi Pico Using Threading

Create a Dimmable LED with a Potentiometer on the Raspberry Pi

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