Add example code for Adafruit IO + QR Codes guide

Author: jepler

CircuitPython_qr_io/code.py

@@ -0,0 +1,137 @@
+# SPDX-FileCopyrightText: Copyright (c) 2021 Jeff Epler for Adafruit Industries
+#
+# SPDX-License-Identifier: Unlicense
+
+"""
+This demo is designed for the Kaluga development kit version 1.3 with the
+ILI9341 display.  Your secrets.py must be populated with your wifi credentials
+and your Adafruit IO credentials.
+"""
+
+import ssl
+from secrets import secrets
+from ulab import numpy as np
+from terminalio import FONT
+import board
+import busio
+import displayio
+import qrio
+import socketpool
+import wifi
+import adafruit_ov2640
+from adafruit_display_text.bitmap_label import Label
+from adafruit_ili9341 import ILI9341
+from adafruit_io.adafruit_io import IO_MQTT
+import adafruit_minimqtt.adafruit_minimqtt as MQTT
+
+# To change the name of the feed on adafruit_io, just modify this string:
+feed_name = "qrstring"
+
+print("Initializing display")
+displayio.release_displays()
+spi = busio.SPI(MOSI=board.LCD_MOSI, clock=board.LCD_CLK)
+display_bus = displayio.FourWire(
+    spi, command=board.LCD_D_C, chip_select=board.LCD_CS, reset=board.LCD_RST
+)
+display = ILI9341(display_bus, width=320, height=240, rotation=90)
+
+print("Initializing camera")
+bus = busio.I2C(scl=board.CAMERA_SIOC, sda=board.CAMERA_SIOD)
+cam = adafruit_ov2640.OV2640(
+    bus,
+    data_pins=board.CAMERA_DATA,
+    clock=board.CAMERA_PCLK,
+    vsync=board.CAMERA_VSYNC,
+    href=board.CAMERA_HREF,
+    mclk=board.CAMERA_XCLK,
+    mclk_frequency=20_000_000,
+    size=adafruit_ov2640.OV2640_SIZE_QQVGA,
+)
+cam.flip_x = False
+cam.flip_y = False
+cam.colorspace = adafruit_ov2640.OV2640_COLOR_YUV
+
+print("Connecting to WIFI")
+wifi.radio.connect(secrets["ssid"], secrets["password"])
+pool = socketpool.SocketPool(wifi.radio)
+
+print("Connecting to Adafruit IO")
+mqtt_client = MQTT.MQTT(
+    broker="io.adafruit.com",
+    username=secrets["aio_username"],
+    password=secrets["aio_key"],
+    socket_pool=pool,
+    ssl_context=ssl.create_default_context(),
+)
+mqtt_client.connect()
+io = IO_MQTT(mqtt_client)
+# Blank out any previously published message
+io.publish(feed_name, "\ufeff")
+
+qrdecoder = qrio.QRDecoder(cam.width, cam.height)
+bitmap = displayio.Bitmap(cam.width, cam.height, 65536)
+
+# Create a greyscale palette
+pal = displayio.Palette(256)
+for i in range(256):
+    pal[i] = 0x10101 * i
+
+label = Label(
+    font=FONT,
+    text="Scan QR Code...",
+    color=0xFFFFFF,
+    background_color=0x0,
+    padding_top=2,
+    padding_left=2,
+    padding_right=2,
+    padding_bottom=2,
+    anchor_point=(0.5, 1.0),
+    anchored_position=(160, 230),
+)
+# Show the camera image at 2x size
+g1 = displayio.Group(scale=2)
+view = np.frombuffer(bitmap, dtype=np.uint8)
+tg = displayio.TileGrid(
+    bitmap,
+    pixel_shader=pal,
+)
+tg.flip_y = True
+g1.append(tg)
+g = displayio.Group()
+g.append(g1)
+g.append(label)
+display.show(g)
+display.auto_refresh = False
+
+i = 0
+spin = ".oOo"
+old_payload = None
+while True:
+    cam.capture(bitmap)
+
+    for row in qrdecoder.decode(bitmap, qrio.PixelPolicy.EVEN_BYTES):
+        payload = row.payload
+        try:
+            payload = payload.decode("utf-8")
+        except UnicodeError:
+            payload = str(payload)
+        if payload != old_payload:
+            label.text = payload
+            print(payload)
+            for i in range(3):
+                try:
+                    io.publish(feed_name, payload)
+                    old_payload = payload
+                    break
+                except OSError as e:
+                    print(e)
+                    mqtt_client.reconnect()
+            old_payload = payload
+        else:
+            print(end="+")
+    print(spin[(i := (i + 1) % len(spin))], end="\10")
+
+    # Clear out the odd bytes, so that the bitmap displays as greyscale
+    view[1::2] = 0
+    bitmap.dirty()
+    display.refresh(minimum_frames_per_second=0)