Receiver Full Tilt Control & Stop Range

In addition to displaying the diamond when the y-axis tilt is close to level, the radio_tilt_bot_fb_with_stop_range script also makes the cyber:bot stay still.

Example script: radio_tilt_bot_fb_with_stop_range

  •     If you are in a classroom, adjust the channel= in the script to your assigned channel.
  •     Make sure the PWR switch is set to 1 first.
  •     Enter, save, and flash radio_tilt_bot_fb_with_stop_range into the micro:bit that's in the receiver cyber:bot.  
# radio_tilt_bot_fb_with_stop_range

from cyberbot import *
import radio

radio.on()
radio.config(channel=7, queue=1, length=64)

while True:

    packet = radio.receive()

    if packet:

        dictionary = eval(packet)
        x = dictionary.get('x')
        y = dictionary.get('y')
        needle = dictionary.get('needle') 

        fb = y / 10

        if abs(fb) > 8:
            display.show(Image.ALL_CLOCKS[needle])
            vL = fb
            vR = -fb
        else:
            display.show(Image.DIAMOND_SMALL)
            vL = None
            vR = None
       

        bot(18).servo_speed(vL)
        bot(19).servo_speed(vR)
  • Tilt the micro:bit transmitter and verify that the receiver cyber:bot displays a copy of the needle.
  • Hold the micro:bit tilt transmitter level, with the LEDs upward and the USB connector pointing toward you.
  • Verify that both the transmitter and receiver micro:bits display a diamond.
  • Set the cyber:bot board PWR switch to 2.

While still holding the transmitter micro:bit level, does the cyber:bot stay still?

As you tilt the tilt transmitter away from and then toward you, does it make the cyber:bot roll forward and backward?

  • Set the PWR switch back to 1.

How It Works

Here is the portion of radio_tilt_bot_fb_with_stop_range that’s different from the previous radio_tilt_bot_fb_only that it’s based on.  

        if abs(fb) > 8:
            display.show(Image.ALL_CLOCKS[needle])
            vL = fb
            vR = -fb
        else:
            display.show(Image.DIAMOND_SMALL)
            vL = None
            vR = None


Keep in mind that fb is y / 8, so instead of looking for y being outside the +/- 80 range, this program checks if fb is outside the +/- 8 range.  When the absolute value of fb is greater than 8, the script displays the tilt needle and sets the vL and vR variables just like it did in the previous radio_tilt_bot_fb_only script.  But when fb falls inside the -8 to 8 range, it displays the diamond and sets vL and vR to None.   

Whenever the else block sets vL and vR to None, it makes the servos stay still.  It’s actually better than setting vL and vR to zero because None causes servo_speed to stop sending control signals.  This prevents any slow wheel rotation that might otherwise occur when the servos are slightly out of calibration and the speeds are set to 0.   

        bot(18).servo_speed(vL)
        bot(19).servo_speed(vR)