add LED examples

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)