add lcd viewfinder example

Author: jepler

circuitpython-esp32-camera/esp32-s3-eye-lcdview/code.py

@@ -0,0 +1,56 @@
+# SPDX-FileCopyrightText: 2017 Scott Shawcroft, written for Adafruit Industries
+# SPDX-FileCopyrightText: Copyright (c) 2021 Jeff Epler for Adafruit Industries
+#
+# SPDX-License-Identifier: Unlicense
+
+"""
+Use the built-in LCD as a viewfinder for the camera
+
+This example requires:
+ * ESP32-S3-EYE development kit from Espressif
+
+To use:
+
+Copy the project bundle to CIRCUITPY.
+"""
+
+import os
+import struct
+import time
+
+import adafruit_ticks
+import esp32_camera
+import board
+import displayio
+from adafruit_st7789 import ST7789
+
+cam = esp32_camera.Camera(
+    data_pins=board.CAMERA_DATA,
+    external_clock_pin=board.CAMERA_XCLK,
+    pixel_clock_pin=board.CAMERA_PCLK,
+    vsync_pin=board.CAMERA_VSYNC,
+    href_pin=board.CAMERA_HREF,
+    pixel_format=esp32_camera.PixelFormat.RGB565,
+    frame_size=esp32_camera.FrameSize.R240X240,
+    i2c=board.I2C(),
+    external_clock_frequency=20_000_000,
+    framebuffer_count=2,
+    grab_mode=esp32_camera.GrabMode.WHEN_EMPTY)
+
+cam.vflip = True
+
+board.DISPLAY.auto_refresh = False
+display_bus = board.DISPLAY.bus
+
+display_bus.send(36, struct.pack(">hh", 0, 239))
+display_bus.send(42, struct.pack(">hh", 0, 239))
+display_bus.send(43, struct.pack(">hh", 0, 80+239))
+t0 = adafruit_ticks.ticks_ms()
+while True:
+    frame = cam.take(1)
+    if isinstance(frame, displayio.Bitmap):
+        display_bus.send(44, frame)
+        t1 = adafruit_ticks.ticks_ms()
+        fps = 1000 / adafruit_ticks.ticks_diff(t1, t0)
+        print(f"{fps:3.1f}fps")  # typically runs at about 25fps
+        t0 = t1