What happens if your bot wanders away and gets stuck under the couch? Will it sit there patiently waiting for someone to notice and rescue it? Let's give it a voice so it can at least call for help.
We could use the Circuit Playground Express's on board speaker to play a sound file or a tone. But that takes up a fair bit of memory, and is Circuit Playground Express specific. Part of the goal with this project is to focus on the CRICKIT, regardless of which model it is.
We could use the speaker output, but again that consumes memory for the waveform to play. The simplest solution that will address the problem (giving the bot a voice) is to use a drive output to switch on and off a buzzer. The one listed in the parts list is perfect for this: apply 5v and it outputs a steady, piercing 2kHz tone. The CRICKIT's drive outputs work at 5v.
You can also solder some wires to the buzzer to make the pins longer instead of stacking header pins.
The positive lead of the buzzer connects to the 5v connection in the drive section of the CRICKIT, and the other buzzer lead connects to one of the drive connections.
The leads on the buzzer line up nicely with the 5v and Drive 2 connectors, but are too short to reach. To solve this, you can use a 4-position long piece of stacking header. Pull out the middle 2 pins, leaving the outer two. This is just the right width for the buzzer leads. Bend the header pins as needed and secure them in the drive screw terminals as shown.
Now it's just a matter of inserting the buzzer pins into the header. Note the `+` pin on the buzzer. It has to be at the 5v connection on the CRICKIT.
Code
Adding the buzzer enables the bot to scream for help. The only additional code is at the very end. After exiting the loop and turning off the motors, the buzzer lets the bot call for help.
while True: for _ in range(3): crickit.drive_2.fraction = 1.0 time.sleep(0.1) crickit.drive_2.fraction = 0.0 time.sleep(.2) time.sleep(10.0)
Setting drive 2's fraction property to 1.0 turns the buzzer on, and setting it to 0.0 turns it off. This code sounds three short beeps every ten seconds. Very simple, yet very effective.
Save the code below as code.py on the Circuit Playground Express.
# SPDX-FileCopyrightText: 2018 Dave Astels for Adafruit Industries
#
# SPDX-License-Identifier: MIT
import time
import random
from adafruit_crickit import crickit
LEFT = False
RIGHT = True
random.seed(int(time.monotonic()))
ss = crickit.seesaw
left_wheel = crickit.dc_motor_1
right_wheel = crickit.dc_motor_2
RIGHT_BUMPER = crickit.SIGNAL1
LEFT_BUMPER = crickit.SIGNAL2
CENTER_BUMPER = crickit.SIGNAL3
ss.pin_mode(RIGHT_BUMPER, ss.INPUT_PULLUP)
ss.pin_mode(LEFT_BUMPER, ss.INPUT_PULLUP)
ss.pin_mode(CENTER_BUMPER, ss.INPUT_PULLUP)
# These allow easy correction for motor speed variation.
# Factors are determined by observation and fiddling.
# Start with both having a factor of 1.0 (i.e. none) and
# adjust until the bot goes more or less straight
def set_right(speed):
right_wheel.throttle = speed * 0.9
def set_left(speed):
left_wheel.throttle = speed
# Uncomment this to find the above factors
# set_right(1.0)
# set_left(1.0)
# while True:
# pass
# Check for bumper activation and move away accordingly
# Returns False if we got clear, True if we gave up
def react_to_bumpers():
attempt_count = 0
# keep trying to back away and turn until we're free
while True:
# give up after 3 tries
if attempt_count == 3:
return True
bumped_left = not ss.digital_read(LEFT_BUMPER)
bumped_right = not ss.digital_read(RIGHT_BUMPER)
bumped_center = not ss.digital_read(CENTER_BUMPER)
# Didn't bump into anything, we're done here
if not bumped_left and not bumped_right and not bumped_center:
return False
# If the middle bumper was triggered, randomly pick a way to turn
if bumped_center:
bumped_left |= random.randrange(10) < 5
bumped_right = not bumped_left
# Back away a bit
set_left(-0.5)
set_right(-0.5)
time.sleep(0.5)
# If we bumped on the left, turn to the right
if bumped_left:
set_left(1.0)
set_right(0.0)
# If we bumped on the right, turn left
elif bumped_right:
set_left(0.0)
set_right(1.0)
# time to turn for
time.sleep(random.choice([0.2, 0.3, 0.4]))
attempt_count += 1
def tack(direction, duration):
target_time = time.monotonic() + duration
if direction == LEFT:
set_left(0.25)
set_right(1.0)
else:
set_left(1.0)
set_right(0.25)
while time.monotonic() < target_time:
if not(ss.digital_read(LEFT_BUMPER) and
ss.digital_read(RIGHT_BUMPER) and
ss.digital_read(CENTER_BUMPER)):
return react_to_bumpers()
return False
while True:
if tack(LEFT, 0.75):
break
if tack(RIGHT, 0.75):
break
set_left(0)
set_right(0)
while True:
for _ in range(3):
crickit.drive_2.fraction = 1.0
time.sleep(0.1)
crickit.drive_2.fraction = 0.0
time.sleep(.2)
time.sleep(10.0)
Text editor powered by tinymce.
