SunFounder Thales Kit, Manual

Page: 66 / 167

SunFounder Thales Kit for Raspberry Pi Pico, Release 1.0
When the program runs, it will start counting and print the numbers in the shell. When we press the button, it will stop
counting and enter the callback function to print “You press the button!”.
Go back to the original example. We need to make the LED turn off in a random time of 5 to 10 seconds, which is
achieved by the following two lines:
import machine
import utime
import urandom
led = machine . Pin( 15 , machine . Pin . OUT)
button = machine . Pin( 14 , machine . Pin . IN)
def button_press (pin):
button . irq(handler = None )
rection_time = utime . ticks_diff(utime . ticks_ms(), timer_light_off)
print ( "Your reaction time was " + str (rection_time) + " milliseconds!" )
led . value( 1 )
utime . sleep(urandom . uniform( 5 , 10 ))
led . value( 0 )
timer_light_off = utime . ticks_ms()
button . irq(trigger = machine . Pin . IRQ_RISING, handler = button_press)
The urandom library is loaded here. Use the urandom.uniform(5,10) function to generate a random number,
the ‘uniform’ part referring to a uniform distribution between those two numbers.
If needed, try running the following example of random number generation:
import machine
import utime
import urandom
while True :
print (urandom . uniform( 1 , 20 ))
utime . sleep( 1 )
The last two statements you need to understand are
utime.ticks_ms()
and
utime.ticks_diff()
.
import machine
import utime
import urandom
led = machine . Pin( 15 , machine . Pin . OUT)
button = machine . Pin( 14 , machine . Pin . IN)
def button_press (pin):
button . irq(handler = None )
rection_time = utime . ticks_diff(utime . ticks_ms(), timer_light_off)
print ( "Your reaction time was " + str (rection_time) + " milliseconds!" )
led . value( 1 )
utime . sleep(urandom . uniform( 5 , 10 ))
led . value( 0 )
timer_light_off = utime . ticks_ms()
button . irq(trigger = machine . Pin . IRQ_RISING, handler = button_press)
• The
utime.ticks_ms()
function will output the number of milliseconds that have passed since the
utime
library started counting and store it in the variable
timer_light_off
.
62 Chapter 3. For MicroPython User