SparkFun Qwiic Quad Solid State Relay Kit Hookup Guide

Contributors: El Duderino, Englandsaurus

Python Examples

Now that you have the Qwiic Relay Py package installed, it's time to check out the examples included with the package.

Example 1 - The Basics

This example demonstrates the basics of turning relays on and off. The code initializes the Qwiic Quad Solid State Relay on the I²C bus, turns on relays 1 and 3 and prints the status of all relays.

language:python
 if myRelays.begin() == False:
    print("The Qwiic Relay isn't connected to the system. Please check your connection", \
        file=sys.stderr)
    return

#Turn on relays one and three
myRelays.set_relay_on(1)
myRelays.set_relay_on(3)
time.sleep(1)

#Print the status of all relays
for relayNum in range(4):
    current_status = None
    if myRelays.get_relay_state(relayNum) is True:
        current_status = "On"
    else:
        current_status = "Off"
    print("Status 1: " + current_status + "\n")

Next, the code turns off relays 1 and 3 and turns on relays 2 and 4.

language:python
#Turn off 1 and 3, turn on 2 and 4
myRelays.set_relay_off(1)
myRelays.set_relay_on(2)
myRelays.set_relay_off(3)
myRelays.set_relay_on(4)
time.sleep(1)

Finally, the code turns all relays on for one second and then turns them all off.

language:python
#Turn all relays on, then turn them all off
myRelays.set_all_relays_on()
time.sleep(1)

myRelays.set_all_relays_off()

With the basics of toggling all the relays, it's time to move on to using the Slow PWM function to pulse our Solid State Relays.

Example 2 - Slow PWM

The second example included with the Python package demonstrates how to use the set_slow_pwm() function. The example starts just like the first by initializing the Quad SSR Kit on the I²C bus and then sets the PWM duty-cycle for each relay and uses the get_slow_pwm() function to print the PWM value set for each relay:

language:python
myRelays.set_slow_pwm(1, 30) #25% duty cycle
myRelays.set_slow_pwm(2, 60) #50% duty cycle
myRelays.set_slow_pwm(3, 90) #75% duty cycle
myRelays.set_slow_pwm(4, 120) #100% duty cycle

for relay_num in range(4):
    pwm_value = myRelays.get_slow_pwm(relay_num)
    print("PWM Value for relay ")
    print(relay_num)
    print(": ")
    print(pwm_value)
#Let the slow PWM run for a while
time.sleep(15)

Each relay is set to a different duty cycle to demonstrate how that affects the behavior of the load and will run for 15 seconds. Want your relay to pulse at a 50% duty cycle? Set the slow PWM value to 60. Note: Just like the Arduino Library, the PWM resolution is limited to 0-120 since there are only 120 times where the zero crossing relay can switch in one second.

After our 15 seconds is up, the code turns all relays off by setting the PWM value to 0 and prints out the new PWM values:

language:python
myRelays.set_slow_pwm(1, 0)
myRelays.set_slow_pwm(2, 0)
myRelays.set_slow_pwm(3, 0)
myRelays.set_slow_pwm(4, 0)


for relay_num in range(4):
    pwm_value = myRelays.get_slow_pwm(relay_num)
    print("PWM Value for relay ")
    print(relay_num)
    print(": ")
    print(pwm_value)

That's all for the basics of our Python package! Try using the various functions included here to write your own code for your next relay project.