Showing posts with label distance measurement. Show all posts
Showing posts with label distance measurement. Show all posts

Thursday 23 December 2021

Hug Avoider 3 - experiments with Python and 4Tronix Eggbit

via GIPHY


4Tronix's Eggbit (in fact I bought three of them 
https://shop.4tronix.co.uk/collections/bbc-micro-bit/products/eggbit-three-pack-special  :-) recently) is a cute add-on for the microbit (see above). In two previous posts I looked at eggbit using microcode to  produce a hug avoider - warns when people at too close.

This post replicates some of this, but this time using Python and shows the stages of the build
  • Get the ultrasound to find the distance;
  • Produce smile and surprise on the eggbit's 'mouth';
  • Produce rainbow on the neopixels or all the pixels turning red;
  • Bring it all together so if the person is too close, less than 30cm it reacts.

 
1. Ultrasonic detection

Probably the most challenging bit of this was getting the ultrasonic distance measrement working. It actually is not that difficult; especially using code from  https://firialabs.com/blogs/lab-notes/ultrasonic-distance-sensor-with-python-and-the-micro-bit as the basis of the solution and pin15 does both triggering and receiving. Code sends a pulse out, picked up  and processed to get the distance from the delay. The code is shown below:

from microbit import *
from machine import time_pulse_us

sonar =pin15
sonar.write_digital(0)

while True:
    sonar.write_digital(1)
    sonar.write_digital(0)
    
    timeus=time_pulse_us(sonar,1)
    echo=timeus/1000000
    dist=(echo/2)*34300
    sleep(100)
    display.scroll(str(dist))


2. LEDs
To get a greater understanding of how 4Tronix's makecode extension (used in the previou posts) for the Eggbit controls the various pins the best resource was to reverse engineering the code  from https://github.com/4tronix/EggBit/blob/main/eggbit.ts in their github respository for the Eggbit. 

This gave the colours and the correct pin for the LEDs the code is shown below. Producing a rainbow method and a method to set the LEDs/neopixels to red. 

import neopixel


fireled=neopixel.NeoPixel(pin13,9)

def rainbow():
    fireled[0] = (255, 0, 40)
    fireled[1]=  (255,165,0)
    #block=yellow
    fireled[2] = (255,255,0)
    #block=green
    fireled[3] = (0,255,0)
    #block=blue
    fireled [4] = (0,0,255)
    # block=indigo
    fireled[5] = (75,0,130)
    # block=violet
    fireled[6] = (138,43,178)
    #block=purple
    fireled[7] = (255,0,255)
    fireled.show()
    
def blank_it():
    for j in range(8):
        fireled[j] = (63, 0, 0)
    fireled.show()



3. 'Face'
Eggbit has set of LEDs that represent a mouth, controlled via three pins. Only two of those are used in this example

'Smile' is pin2.write_digital(1) the 'lower' part of the mouth and turn off upper part of the mouth pin0.write_digital(0)

'Surprise' uses both parts 
pin2.write_digital(1)
pin0.write_digital(1)


4. Overall

So putting this altogether 

from microbit import *
from machine import time_pulse_us
import neopixel

sonar =pin15
sonar.write_digital(0)
fireled=neopixel.NeoPixel(pin13,9)

def rainbow():
    fireled[0] = (255, 0, 40)
    fireled[1]=  (255,165,0)
    #block=yellow
    fireled[2] = (255,255,0)
    #block=green
    fireled[3] = (0,255,0)
    #block=blue
    fireled [4] = (0,0,255)
    # block=indigo
    fireled[5] = (75,0,130)
    # block=violet
    fireled[6] = (138,43,178)
    #block=purple
    fireled[7] = (255,0,255)
    fireled.show()
    
def blank_it():
    for j in range(8):
        fireled[j] = (63, 0, 0)
    fireled.show()

def howfar():
    sonar.write_digital(1)
    sonar.write_digital(0)
    
    timeus=time_pulse_us(sonar,1)
    echo=timeus/1000000
    dist=(echo/2)*34300
    sleep(100)
    return dist

while True:
    dist=howfar()
    if dist>30:
        pin2.write_digital(1)
        pin0.write_digital(0)
        rainbow()
        display.show(Image.HAPPY)
    else:
        pin2.write_digital(1)
        pin0.write_digital(1)
        blank_it()
        display.show(Image.ANGRY)



All opinions in this blog are the Author's and should not in any way be seen as reflecting the views of any organisation the Author has any association with. Twitter @scottturneruon

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