Add LEDC servo example and add LEDC examples to readme

vickash · vickash · commit 7ca1b6d353a9 · 2023-07-08T20:09:18.000-04:00
diff --git a/README.md b/README.md
@@ -39,6 +39,9 @@ The valiable `YOU_WISH_TO_TRY_FILE` can be replaced with one of the following:
   * _wifi_connect.rb_ - Connects to WiFi. You need to replace your SSID and password in this file.
   * _mqtt_publish.rb_ - Publishes to MQTT broker
   * _filesystem.rb_ - Write/Append/Read example 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 pizeo-electric buzzer
+  * _ledc_servo.rb_ - Controls position of a 180 degree hobby servo motor
 
 The clean command will clean both the ESP32 build and the mruby build:
 
diff --git a/main/examples/ledc_servo.rb b/main/examples/ledc_servo.rb
@@ -0,0 +1,37 @@
+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::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
+
+# This is for a 180 degree MG995 motor. Values will differ for other sweep angles,
+# or continuous rotation servos / ESCs. Values may vary between individual motors.
+#
+# Make sure to connect your servo motor to a separate power source!
+#
+5.times do
+  # Send 500us pulses for 2 seconds. Should map to 0 degrees.
+  ESP32::LEDC.set_duty(group, channel, microseconds_to_duty(500))
+  ESP32::System.delay(2000)
+  
+  # Send 2500us pulses for 2 seconds. Should map to 180 degrees.
+  ESP32::LEDC.set_duty(group, channel, microseconds_to_duty(2500))
+  ESP32::System.delay(2000)
+end
+
+# Turn it off.
+ESP32::LEDC.set_duty(group, channel, 0)
