Tag Archives: State Machines

In this video lesson we will show you how to get precise distance measurements with the HC-SR04 Ultrasonic sensor. We show how measurement stability and accuracy can be improved by using the Raspberry Pi Pico PIO State Machines to trigger and monitor the sensor. For your convenience, the code is presented 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.
# ====================================================================

import rp2
from machine import Pin
import time

@rp2.asm_pio(set_init=rp2.PIO.OUT_LOW)
def pulse_program():
    wrap_target()
    pull(block)
    mov(x,osr)
    set(pins,1)[10-1]
    set(pins,0)
    wait(1,pin,0)
    label("land")
    mov(y,pins) # 1 clock cycle
    jmp(not_y,"moveOn") #1 clock cycle
    jmp(x_dec,"land") # 1 clock cycle
    label("moveOn")
    mov(isr,invert(x))
    push()
    wrap()
triggerPin = Pin(16,Pin.OUT)
echoPin = Pin(17, Pin.IN)
sm=rp2.StateMachine(0,pulse_program, freq=1000000, set_base=triggerPin,in_base=echoPin)
sm.active(1)
ts=.25
while True:
    sm.put(0xFFFFFFFF)
    print("Pulse Launched")
    clockCycles=sm.get()*3/2
    distance=clockCycles*.0342
    print("Distance to Target: ",distance)
    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 rp2

from machine import Pin

import time

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

def pulse_program():

wrap_target()

pull(block)

mov(x,osr)

set(pins,1)[10-1]

set(pins,0)

wait(1,pin,0)

label("land")

mov(y,pins) # 1 clock cycle

jmp(not_y,"moveOn") #1 clock cycle

jmp(x_dec,"land") # 1 clock cycle

label("moveOn")

mov(isr,invert(x))

push()

wrap()

triggerPin = Pin(16,Pin.OUT)

echoPin = Pin(17, Pin.IN)

sm=rp2.StateMachine(0,pulse_program, freq=1000000, set_base=triggerPin,in_base=echoPin)

sm.active(1)

ts=.25

while True:

sm.put(0xFFFFFFFF)

print("Pulse Launched")

clockCycles=sm.get()*3/2

distance=clockCycles*.0342

print("Distance to Target: ",distance)

time.sleep(ts)

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.

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

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

# 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 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

Python, Raspberry Pi Pico

Raspberry Pi Pico PIO State Machine IRQ Interrupts

January 7, 2025 admin

<span data-mce-type="bookmark" style="display: inline-block; width: 0px; overflow: hidden; line-height: 0;" class="mce_SELRES_start"></span> In the video lesson above, we show how to incorporate IRQ interrupts on the Pi Pico PIO State Machines. The state machines will monitor the buttons, watching for button presses. When a button is pressed, an interrupt is set. That interrupt can then be used by that same state machine, a different state machine on the same PIO, or in the main micropython program. Our first example will be to toggle the LED in the main python program, based on the interrupt from the state machine. In the second example, one state machine monitors the button, and the second state machine controls the LED. This is a schematic for the circuit we will be using.

This first code controls the LED from the main python program.

# ====================================================================
# 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 rp2
from machine import Pin
import time

# Define PIO program for SM0 to trigger an interrupt on button press
@rp2.asm_pio()
def button_irq():
    wrap_target()
    wait(1, pin, 0)  [31]  # Wait for the button press (low signal on GPIO 11)
    nop() [31]
    nop() [31]
    nop() [31]
    nop() [31]
    irq(block, 0)      # Trigger interrupt 0
    wait(0, pin, 0)    # Wait for the button release (high signal on GPIO 11)
    nop() [31]
    nop() [31]
    nop() [31]
    nop() [31]
    wrap()
# Initialize State Machine 0 for the button (GPIO 11)
button_pin = Pin(11, Pin.IN, Pin.PULL_DOWN)
sm_button = rp2.StateMachine(0, button_irq, freq=2000, in_base=button_pin)
# GPIO pin for the LED (GPIO 18)
led_pin = Pin(18, Pin.OUT)
# Interrupt handler for the button press
def button_handler(sm):
    led_pin.value(not led_pin.value())  # Toggle LED state
# Attach the interrupt handler to the State Machine's IRQ
sm_button.irq(button_handler)
# Activate the state machine
sm_button.active(1)

# Keep the program running
ts=1
while True:
    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 rp2

from machine import Pin

import time

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

@rp2.asm_pio()

def button_irq():

wrap_target()

wait(1, pin, 0) [31] # Wait for the button press (low signal on GPIO 11)

nop() [31]

irq(block, 0) # Trigger interrupt 0

wait(0, pin, 0) # Wait for the button release (high signal on GPIO 11)

nop() [31]

wrap()

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

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

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

# GPIO pin for the LED (GPIO 18)

led_pin = Pin(18, Pin.OUT)

# Interrupt handler for the button press

def button_handler(sm):

led_pin.value(not led_pin.value()) # Toggle LED state

# Attach the interrupt handler to the State Machine's IRQ

sm_button.irq(button_handler)

# Activate the state machine

sm_button.active(1)

# Keep the program running

ts=1

while True:

time.sleep(ts)

This next program uses only the state machines. Interrupts and LED control are both done in the state machines.

# ====================================================================
# 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 rp2
from machine import Pin
import time

@rp2.asm_pio()
def button_irq():
    wrap_target()
    wait(1, pin, 0) [31]
    nop() [31]
    nop() [31]
    nop() [31]
    nop() [31]
    irq(block,0)
    wait(0,pin,0)
    nop() [31]
    nop() [31]
    nop() [31]
    nop() [31]
    wrap()

@rp2.asm_pio(out_init=rp2.PIO.OUT_LOW)
def led_control():
    set(x,0b00000)
    wrap_target()
    wait(1, irq, 0)
    mov(x,invert(x))
    mov(pins,x)
    irq(clear, 0)
    wrap()

button_pin = Pin(11,Pin.IN,Pin.PULL_DOWN)
sm_button=rp2.StateMachine(0,button_irq, freq=2000, in_base=button_pin)

led_pin = Pin(18, Pin.OUT)
sm_led=rp2.StateMachine(1, led_control, freq=2000, out_base=led_pin)
sm_button.active(1)
sm_led.active(1)

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

# 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 rp2

from machine import Pin

import time

@rp2.asm_pio()

def button_irq():

wrap_target()

wait(1, pin, 0) [31]

nop() [31]

irq(block,0)

wait(0,pin,0)

nop() [31]

wrap()

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

def led_control():

set(x,0b00000)

wrap_target()

wait(1, irq, 0)

mov(x,invert(x))

mov(pins,x)

irq(clear, 0)

wrap()

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

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

led_pin = Pin(18, Pin.OUT)

sm_led=rp2.StateMachine(1, led_control, freq=2000, out_base=led_pin)

sm_button.active(1)

sm_led.active(1)

MicroPython, Raspberry Pi Pico

Using Multiple Raspberry Pi Pico PIO State Machines at the Same Time

December 17, 2024 admin

In this video lesson we show how you can work with more than one state machine at the same time in microPython on the Raspberry Pi Pico W. We show this in the context or controlling multiple servos. We show different ways to utilize multiple state machines. For your convenience, we provide the code developed in the video below. Enjoy!

# ====================================================================
# 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 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)")
sm1 = rp2.StateMachine(1,servoSet, freq=2000000, set_base=Pin(21))
sm1.active(1)
sm1.put(20000)
sm1.exec("pull()")
sm1.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()")
        sm1.put(3000-pw)
        sm1.exec("pull()")
    ts=5
    time.sleep(ts)
    for angle in range(180,0,-1):
        pw=int(500+angle*2000/180)
        sm0.put(pw)
        sm0.exec("pull()")
        sm1.put(3000-pw)
        sm1.exec("pull()")

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

# 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 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)")

sm1 = rp2.StateMachine(1,servoSet, freq=2000000, set_base=Pin(21))

sm1.active(1)

sm1.put(20000)

sm1.exec("pull()")

sm1.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()")

sm1.put(3000-pw)

sm1.exec("pull()")

ts=5

time.sleep(ts)

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

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

sm0.put(pw)

sm0.exec("pull()")

sm1.put(3000-pw)

sm1.exec("pull()")

Technology Tutorials

Tag Archives: State Machines

Precision Ultrasonic Distance Measurement With PIO State Machines on Raspberry Pi Pico W

Raspberry Pi Pico PIO State Machine IRQ Interrupts and Handlers

Raspberry Pi Pico PIO State Machine IRQ Interrupts

Using Multiple Raspberry Pi Pico PIO State Machines at the Same Time

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