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Add/improve MQTT examples for event driven update #46

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2 changes: 2 additions & 0 deletions README.md
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Original file line number Diff line number Diff line change
Expand Up @@ -50,6 +50,8 @@ Replace `EXAMPLE_FILENAME` with one of the following:
* `wifi_connect.rb` - Connects to WiFi
* `wifi_socket.rb` - Connects to WiFi and makes a TCPSocket connection
* `mqtt_publish.rb` - Connects to WiFi and publishes to MQTT broker
* `mqtt_subscribe.rb` - Connects to WiFi, subscribes to MQTT broker, and prints received messages
* `mqtt_led_servo.rb` - Receives microsecond values over MQTT and writes them to a servo, while blinking LED in main loop
* `filesystem.rb` - Write/append/read a file on the virtual filesystem
* `ledc_breathe.rb` - Gradually fades the brightness of an LED up and down
* `ledc_buzzer.rb` - Plays a melody on a piezo-electric buzzer
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56 changes: 56 additions & 0 deletions main/examples/mqtt_led_servo.rb
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@@ -0,0 +1,56 @@
#
# Servo Setup
#
group = ESP32::LEDC_LOW_SPEED_MODE
channel = ESP32::LEDC_CHANNEL_0
timer = ESP32::LEDC_TIMER_0
resolution = ESP32::LEDC_TIMER_14_BIT
pin = ESP32::GPIO_NUM_4
frequency = 50

# Configure the channel and timer.
ESP32::LEDC.channel_config(pin, group, timer, channel)
ESP32::LEDC.timer_config(group, timer, resolution, frequency)

# Using 14-bit PWM @ 50Hz, 0-16383 maps from 0 to 20 milliseconds.
# Calculate how many microseconds each LSB of duty cycle represents.
US_PER_BIT = (1000000.0 / frequency) / (2 ** resolution)

# Convert from microseconds to duty cycle.
def microseconds_to_duty(us)
(us / US_PER_BIT).round
end

#
# WiFi Setup
#
print 'Connecting to wifi...'
wifi = ESP32::WiFi.new
wifi.connect('SSID', 'password')
puts "Connected"

#
# MQTT Setup
#
mqtt = ESP32::MQTT::Client.new('test.mosquitto.org', 1883)
mqtt.connect
mqtt.subscribe("mruby-esp32-mqtt") do |message|
puts "Servo mircoseconds: #{message}"
# Send microsecond values to move the servo.
ESP32::LEDC.set_duty(group, channel, microseconds_to_duty(message.to_i))
end

#
# Blink LED in main loop.
#
led = ESP32::GPIO_NUM_2
ESP32::GPIO::pinMode(led, ESP32::GPIO::OUTPUT)
loop do
ESP32::GPIO::digitalWrite(led, ESP32::GPIO::HIGH)
ESP32::System.delay(1000)
ESP32::GPIO::digitalWrite(led, ESP32::GPIO::LOW)
ESP32::System.delay(1000)
end

# Send a message using another MQTT client, or a site like:
# https://testclient-cloud.mqtt.cool/
4 changes: 1 addition & 3 deletions main/examples/mqtt_publish.rb
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print 'Connecting to wifi...'
wifi = ESP32::WiFi.new

puts 'Connecting to wifi'
wifi.connect('SSID', 'password')

puts "Connected"

mqtt = ESP32::MQTT::Client.new('test.mosquitto.org', 1883)
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20 changes: 20 additions & 0 deletions main/examples/mqtt_subscribe.rb
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TOPIC = "mruby-esp32-mqtt"

print 'Connecting to wifi...'
wifi = ESP32::WiFi.new
wifi.connect('SSID', 'password')
puts "Connected"

mqtt = ESP32::MQTT::Client.new('test.mosquitto.org', 1883)
mqtt.connect
mqtt.subscribe(TOPIC) do |message|
puts "Topic: #{topic}, message: #{message}"
end

# Message receive is event driven, so main loop can do whatever.
loop do
ESP32::System.delay(1000)
end

# Send a message using another MQTT client, or a site like:
# https://testclient-cloud.mqtt.cool/