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)
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