Merge pull request #19 from pimoroni/examples/leds

add LED examples

docs/reference.md

@@ -230,7 +230,7 @@ PicoGraphics is a wrapper around a big ol' chunk of RAM, which corresponds to th
 
 ## Basic Drawing Functions
 
-Since there are many, many things you can do with PicoGraphics that would be silly to repeat here, I'll send you over to our main MicroPython repository for [a full PicoGraphics function reference.][https://github.com/pimoroni/pimoroni-pico/blob/main/micropython/modules/picographics/README.md#function-reference]
+Since there are many, many things you can do with PicoGraphics that would be silly to repeat here, I'll send you over to our main MicroPython repository for [a full PicoGraphics function reference][https://github.com/pimoroni/pimoroni-pico/blob/main/micropython/modules/picographics/README.md#function-reference]
 
 ## Changing The Display Mode
 

examples/README.md

@@ -40,6 +40,14 @@ Displays light, accelerometer and temperature data!
 
 Gotta put something on that little breadboard, right! How about more buttons. You can never have enough buttons. The ones they keep taking out of cars must go somewhere!?
 
+# external_leds.py
+
+More bling for your breadboard! If you liked it then you should have put an LED on it.
+
+# external_rgb_led.py
+
+What's better than an ordinary LED? A RGB LED! (it's actually three teeny tiny ordinary LEDs smooshed together, but don't tell anyone!)
+
 # image_gallery.py
 
 At a loss for what to do with your Explorer. Clock just not your cup of tea? How about a digital photo frame! Those are still cool, right?

examples/external_leds.py

@@ -0,0 +1,46 @@
+"""
+Connect (up to) 3 LEDs to Explorer and turn them on and off with buttons A, B and C.
+
+Wire the long leg of your LEDs up to GP0, GP1 and GP2. The other leg should be wired to ground.
+(Note that you don't need to include a resistor in your circuit to current-limit the LEDs with Explorer, as there are resistors on the board).
+"""
+
+from machine import Pin
+import time
+from explorer import display, button_a, button_b, button_c, BLACK, WHITE
+
+# Set up the LEDs
+led_0 = Pin(0, Pin.OUT)
+led_1 = Pin(1, Pin.OUT)
+led_2 = Pin(2, Pin.OUT)
+
+# Clear all layers first
+display.set_layer(0)
+display.set_pen(BLACK)
+display.clear()
+display.set_layer(1)
+display.set_pen(BLACK)
+display.clear()
+
+# Set the layer we're going to be drawing to.
+display.set_layer(0)
+
+# Draw some text to the screen
+display.set_pen(WHITE)
+display.text("Wire up some LEDs to GP0, GP1 and GP2, and then push buttons A, B and C", 0, 0, 320, 4)
+display.update()
+
+while True:
+    # Start the loop with all LEDs off
+    led_0.off()
+    led_1.off()
+    led_2.off()
+    # Because we're using Pin.PULL_UP the logic is reversed - '0' is pushed and '1' is unpushed
+    if button_a.value() == 0:
+        led_0.on()
+    if button_b.value() == 0:
+        led_1.on()
+    if button_c.value() == 0:
+        led_2.on()
+    # Short pause to stop Thonny from falling over
+    time.sleep(0.01)

examples/external_rgb_led.py

@@ -0,0 +1,80 @@
+"""
+Connect an old school four legged RGB LED up to Explorer and toggle the Red, Green and Blue channels with buttons A, B and C.
+Press X for rainbows!
+
+Position your LED so the long leg is pin 2 - this leg should be connected to ground.
+The other three legs (pins 1, 3 and 4) are R, G and B - these should be wired to GP0, GP1 and GP2.
+(Note that you don't need to include resistors in your circuit with Explorer, as there are resistors on the board).
+"""
+import time
+from explorer import display, button_a, button_b, button_c, button_x, BLACK, WHITE
+from pimoroni import RGBLED
+
+
+# From CPython Lib/colorsys.py
+def hsv_to_rgb(h, s, v):
+    if s == 0.0:
+        return v, v, v
+    i = int(h * 6.0)
+    f = (h * 6.0) - i
+    p = v * (1.0 - s)
+    q = v * (1.0 - s * f)
+    t = v * (1.0 - s * (1.0 - f))
+    i = i % 6
+    if i == 0:
+        return v, t, p
+    if i == 1:
+        return q, v, p
+    if i == 2:
+        return p, v, t
+    if i == 3:
+        return p, q, v
+    if i == 4:
+        return t, p, v
+    if i == 5:
+        return v, p, q
+
+
+# Set up an old school 4 pin RGB LED connected to GP0, GP1 and GP2
+led = RGBLED(0, 1, 2, invert=False)
+
+# Variables to keep track of rainbows
+rainbow_mode = False
+h = 0
+
+# Clear all layers first
+display.set_layer(0)
+display.set_pen(BLACK)
+display.clear()
+display.set_layer(1)
+display.set_pen(BLACK)
+display.clear()
+
+# Set the layer we're going to be drawing to.
+display.set_layer(0)
+
+# Draw some text to the screen
+display.set_pen(WHITE)
+display.text("Wire an RGB LED up to GP0, GP1 and GP2, and then press A, B, C or X", 0, 0, 320, 4)
+display.update()
+
+while True:
+    # Toggle rainbow mode if button X is pushed
+    if button_x.value() == 0:
+        rainbow_mode = not rainbow_mode
+    if rainbow_mode is True:  # then apply rainbow magic
+        h += 1
+        r, g, b = [int(255 * c) for c in hsv_to_rgb(h / 360.0, 1.0, 1.0)]
+        led.set_rgb(r, g, b)
+
+    # Because we're using Pin.PULL_UP the logic is reversed - '0' is pushed and '1' is unpushed
+    else:
+        led.set_rgb(0, 0, 0)
+        if button_a.value() == 0:  # set LED to red
+            led.set_rgb(255, 0, 0)
+        if button_b.value() == 0:  # set LED to blue
+            led.set_rgb(0, 255, 0)
+        if button_c.value() == 0:  # set LED to green
+            led.set_rgb(0, 0, 255)
+    # Short pause to stop Thonny from falling over
+    time.sleep(0.01)