Tag Archives: Servo

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.

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()
            time.sleep(.2)
        if decButState==0 and decButStateOld==1:
            servoAngle=servoAngle - 10
            if servoAngle>180:
                servoAngle=180
            if servoAngle<0:
                servoAngle=0
            moveServo()
            unlockStart=time.time()
            time.sleep(.2)
        incButStateOld=incButState
        decButStateOld=decButState

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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()

time.sleep(.2)

if decButState==0 and decButStateOld==1:

servoAngle=servoAngle - 10

if servoAngle>180:

servoAngle=180

if servoAngle<0:

servoAngle=0

moveServo()

unlockStart=time.time()

time.sleep(.2)

incButStateOld=incButState

decButStateOld=decButState

MicroPython, Raspberry Pi Pico

RFID Lock and Unlock Demonstration Project Raspberry Pi Pico W

May 13, 2025 admin

In this video lesson we explore using an RFID-RC522 and an RFID tag to lock and unlock our raspberry pi project. This demonstration will include an RGB LED which remains red while the system is locked, and then turns green when the system is unlocked by the RFID tag. Absence of user input, the system will lock again after 5 seconds. The following is the circuit diagram for the project:

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.

For your convenience, the code for the project is included below:

from mfrc522 import SimpleMFRC522
import time
from machine import Pin, PWM
unlockTime = 5
decPin = 20
incPin = 21
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

butCount = 0

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

def readRFID():
    global cardID
    print()
    print("System LOCKED")
    print("Reading . . . Please Place the Card")
    cardID,readText = reader.read()
    print()
    print("ID: ",cardID)
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:
            butCount=butCount+1
            print("Button Count: ",butCount)
            unlockStart=time.time()
            time.sleep(.2)
        if decButState==0 and decButStateOld==1:
            butCount=butCount-1
            print("Button Count: ",butCount)
            unlockStart=time.time()
            time.sleep(.2)
        incButStateOld=incButState
        decButStateOld=decButState

from mfrc522 import SimpleMFRC522

import time

from machine import Pin, PWM

unlockTime = 5

decPin = 20

incPin = 21

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

butCount = 0

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

def readRFID():

global cardID

print()

print("System LOCKED")

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

cardID,readText = reader.read()

print()

print("ID: ",cardID)

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:

butCount=butCount+1

print("Button Count: ",butCount)

unlockStart=time.time()

time.sleep(.2)

if decButState==0 and decButStateOld==1:

butCount=butCount-1

print("Button Count: ",butCount)

unlockStart=time.time()

time.sleep(.2)

incButStateOld=incButState

decButStateOld=decButState

MicroPython, Raspberry Pi Pico

Control Raspberry Pi Pico PIO State Machines in a Micropython Class

December 24, 2024 admin

In this video lesson we show how you can control a PIO State Machine on the Raspberry Pi Pico W inside of a micropython class. We demonstrate with the practical example of controlling servos with a servo Class which we create. The objective is to ‘hide’ all the complex code in the class, allowing less adept users to interact with the servo with simple python commands. For your convenience the code developed in this video is included below. Enjoy!

import time
from machine import Pin
import rp2
class servoState:
    counter=0
    @rp2.asm_pio(set_init=rp2.PIO.OUT_LOW,out_shiftdir=rp2.PIO.SHIFT_RIGHT)
    def servoSet():
        wrap_target()
        mov(x,osr)
        mov(y,isr)
        set(pins,0)
        label('timeLoop')
        jmp(x_not_y,'nxt')
        set(pins,1)
        label('nxt')
        jmp(y_dec,'timeLoop')    
        wrap()
    
    def __init__(self,servoPin):
        self.sm = rp2.StateMachine(servoState.counter,servoState.servoSet, freq=2000000, set_base=Pin(servoPin))
        self.sm.active(1)
        self.sm.put(20000)
        self.sm.exec("pull()")
        self.sm.exec("mov(isr,osr)")
        print("State Machine: "+str(servoState.counter)+" created")
        servoState.counter=servoState.counter+1
    def servoAngle(self,angle):
        pw=int(500+angle*2000/180)
        self.sm.put(pw)
        self.sm.exec("pull()")
myServo1=servoState(20)
myServo2=servoState(21)
myServo3=servoState(22)
myServo4=servoState(23)
myServo5=servoState(24)
myServo6=servoState(25)
myServo7=servoState(26)
myServo8=servoState(27)
while True:
    for angle in range(0,180,1):
        myServo1.servoAngle(angle)
        myServo7.servoAngle(180-angle)
    time.sleep(5)
    for angle in range(180,0,-1):
        myServo1.servoAngle(angle)
        myServo7.servoAngle(180-angle)
    time.sleep(5)

import time

from machine import Pin

import rp2

class servoState:

counter=0

@rp2.asm_pio(set_init=rp2.PIO.OUT_LOW,out_shiftdir=rp2.PIO.SHIFT_RIGHT)

def servoSet():

wrap_target()

mov(x,osr)

mov(y,isr)

set(pins,0)

label('timeLoop')

jmp(x_not_y,'nxt')

set(pins,1)

label('nxt')

jmp(y_dec,'timeLoop')

wrap()

def __init__(self,servoPin):

self.sm = rp2.StateMachine(servoState.counter,servoState.servoSet, freq=2000000, set_base=Pin(servoPin))

self.sm.active(1)

self.sm.put(20000)

self.sm.exec("pull()")

self.sm.exec("mov(isr,osr)")

print("State Machine: "+str(servoState.counter)+" created")

servoState.counter=servoState.counter+1

def servoAngle(self,angle):

pw=int(500+angle*2000/180)

self.sm.put(pw)

self.sm.exec("pull()")

myServo1=servoState(20)

myServo2=servoState(21)

myServo3=servoState(22)

myServo4=servoState(23)

myServo5=servoState(24)

myServo6=servoState(25)

myServo7=servoState(26)

myServo8=servoState(27)

while True:

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

myServo1.servoAngle(angle)

myServo7.servoAngle(180-angle)

time.sleep(5)

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

myServo1.servoAngle(angle)

myServo7.servoAngle(180-angle)

time.sleep(5)

MicroPython, Raspberry Pi Pico

Sweeping Servo Position Using the PIO State Machine on the Raspberry Pi Pico PIO State Machine

December 10, 2024 admin

In this video lesson we show how you can use the Raspberry Pi Pico PIO State Machine to sweep a servo through its full range of motion. The video will take you through things step-by-step. For your convenience the code developed in the video is included below. Enjoy!

import time
from machine import Pin
import rp2
@rp2.asm_pio(set_init=rp2.PIO.OUT_LOW,out_shiftdir=rp2.PIO.SHIFT_RIGHT)
def servoSet():
    wrap_target()
    mov(x,osr)
    mov(y,isr)
    set(pins,0)
    label('timeLoop')
    jmp(x_not_y,'nxt')
    set(pins,1)
    label('nxt')
    jmp(y_dec,'timeLoop')    
    wrap()  
sm0 = rp2.StateMachine(0,servoSet, freq=2000000, set_base=Pin(20))
sm0.active(1)
sm0.put(20000)
sm0.exec("pull()")
sm0.exec("mov(isr,osr)")
while True:
    for angle in range(0,180,1):
        pw=int(500+angle*2000/180)
        sm0.put(pw)
        sm0.exec("pull()")
    time.sleep(5)
    for angle in range(180,0,-1):
        pw=int(500+angle*2000/180)
        sm0.put(pw)
        sm0.exec("pull()")

import time

from machine import Pin

import rp2

@rp2.asm_pio(set_init=rp2.PIO.OUT_LOW,out_shiftdir=rp2.PIO.SHIFT_RIGHT)

def servoSet():

wrap_target()

mov(x,osr)

mov(y,isr)

set(pins,0)

label('timeLoop')

jmp(x_not_y,'nxt')

set(pins,1)

label('nxt')

jmp(y_dec,'timeLoop')

wrap()

sm0 = rp2.StateMachine(0,servoSet, freq=2000000, set_base=Pin(20))

sm0.active(1)

sm0.put(20000)

sm0.exec("pull()")

sm0.exec("mov(isr,osr)")

while True:

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

pw=int(500+angle*2000/180)

sm0.put(pw)

sm0.exec("pull()")

time.sleep(5)

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

pw=int(500+angle*2000/180)

sm0.put(pw)

sm0.exec("pull()")

MicroPython, Raspberry Pi Pico

Control Servo Position Using a Raspberry Pi Pico PIO State Machine

December 3, 2024 admin

In this video tutorial we show you how you can use a Raspberry Pi Pico PIO Statemachine to control the position of a servo. For your convenience, the code from this lesson is presented below. Enjoy!

from machine import Pin
import rp2
@rp2.asm_pio(set_init=rp2.PIO.OUT_LOW,out_shiftdir=rp2.PIO.SHIFT_RIGHT)
def servoSet():
    set(x,0b11111)
    in_(x,5)
    set(x,0b0100)
    in_(x,4)
    #set(x,0b00000)
    #in_(x,1)
    mov(osr,isr)
    
    mov(isr,null)
    set(y,0b10011)
    in_(y,5)
    set(y,0b10001)
    in_(y,5)
    set(y,0b00000)
    in_(y,5)
    
    wrap_target()
    mov(x,osr)
    mov(y,isr)
    set(pins,0)
    label('timeLoop')
    jmp(x_not_y,'nxt')
    set(pins,1)
    label('nxt')
    jmp(y_dec,'timeLoop')    
    wrap()
    
sm0 = rp2.StateMachine(0,servoSet, freq=2000000, set_base=Pin(20))
sm0.active(1)

from machine import Pin

import rp2

@rp2.asm_pio(set_init=rp2.PIO.OUT_LOW,out_shiftdir=rp2.PIO.SHIFT_RIGHT)

def servoSet():

set(x,0b11111)

in_(x,5)

set(x,0b0100)

in_(x,4)

#set(x,0b00000)

#in_(x,1)

mov(osr,isr)

mov(isr,null)

set(y,0b10011)

in_(y,5)

set(y,0b10001)

in_(y,5)

set(y,0b00000)

in_(y,5)

wrap_target()

mov(x,osr)

mov(y,isr)

set(pins,0)

label('timeLoop')

jmp(x_not_y,'nxt')

set(pins,1)

label('nxt')

jmp(y_dec,'timeLoop')

wrap()

sm0 = rp2.StateMachine(0,servoSet, freq=2000000, set_base=Pin(20))

sm0.active(1)

Technology Tutorials

Tag Archives: Servo

RFID Project to Lock and Unlock Control of Servo

RFID Lock and Unlock Demonstration Project Raspberry Pi Pico W

Control Raspberry Pi Pico PIO State Machines in a Micropython Class

Sweeping Servo Position Using the PIO State Machine on the Raspberry Pi Pico PIO State Machine

Control Servo Position Using a Raspberry Pi Pico PIO State Machine

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