Add a "direct LCD access" example

The "direct LCD access" example shows how to copy the image directly to
an LCD of the right resolution.  It achieves a somewhat higher framerate
(4.1fps vs 2.5fps) but is not compatible with displayio.

Author: jepler

examples/ov2640_directio_kaluga1_3_ili9341.py

@@ -0,0 +1,176 @@
+# SPDX-FileCopyrightText: 2017 Scott Shawcroft, written for Adafruit Industries
+# SPDX-FileCopyrightText: Copyright (c) 2021 Jeff Epler for Adafruit Industries
+#
+# SPDX-License-Identifier: Unlicense
+
+"""
+The Kaluga development kit comes in two versions (v1.2 and v1.3); this demo is
+tested on v1.3.
+
+The audio board must be mounted between the Kaluga and the LCD, it provides the
+I2C pull-ups(!)
+
+The v1.3 development kit's LCD can have one of two chips, the ili9341 or
+st7789.  Furthermore, there are at least 2 ILI9341 variants, which differ
+by rotation.  This example is written for one if the ILI9341 variants,
+the one which usually uses rotation=90 to get a landscape display.
+
+This example also requires an SD card breakout wired as follows:
+ * IO18: SD Clock Input
+ * IO17: SD Serial Output (MISO)
+ * IO14: SD Serial Input (MOSI)
+ * IO12: SD Chip Select
+
+Insert a CircuitPython-compatible SD card before powering on the Kaluga.
+Press the "Record" button on the audio daughterboard to take a photo.
+"""
+
+import os
+import struct
+import time
+
+import analogio
+import board
+import busio
+import displayio
+import sdcardio
+import storage
+from adafruit_ili9341 import ILI9341
+import adafruit_ov2640
+
+V_MODE = 1.98
+V_RECORD = 2.41
+
+a = analogio.AnalogIn(board.IO6)
+
+# Release any resources currently in use for the displays
+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,
+    baudrate=80_000_000,
+)
+_INIT_SEQUENCE = (
+    b"\x01\x80\x80"  # Software reset then delay 0x80 (128ms)
+    b"\xEF\x03\x03\x80\x02"
+    b"\xCF\x03\x00\xC1\x30"
+    b"\xED\x04\x64\x03\x12\x81"
+    b"\xE8\x03\x85\x00\x78"
+    b"\xCB\x05\x39\x2C\x00\x34\x02"
+    b"\xF7\x01\x20"
+    b"\xEA\x02\x00\x00"
+    b"\xc0\x01\x23"  # Power control VRH[5:0]
+    b"\xc1\x01\x10"  # Power control SAP[2:0];BT[3:0]
+    b"\xc5\x02\x3e\x28"  # VCM control
+    b"\xc7\x01\x86"  # VCM control2
+    b"\x36\x01\x40"  # Memory Access Control
+    b"\x37\x01\x00"  # Vertical scroll zero
+    b"\x3a\x01\x55"  # COLMOD: Pixel Format Set
+    b"\xb1\x02\x00\x18"  # Frame Rate Control (In Normal Mode/Full Colors)
+    b"\xb6\x03\x08\x82\x27"  # Display Function Control
+    b"\xF2\x01\x00"  # 3Gamma Function Disable
+    b"\x26\x01\x01"  # Gamma curve selected
+    b"\xe0\x0f\x0F\x31\x2B\x0C\x0E\x08\x4E\xF1\x37\x07\x10\x03\x0E\x09\x00"  # Set Gamma
+    b"\xe1\x0f\x00\x0E\x14\x03\x11\x07\x31\xC1\x48\x08\x0F\x0C\x31\x36\x0F"  # Set Gamma
+    b"\x11\x80\x78"  # Exit Sleep then delay 0x78 (120ms)
+    b"\x29\x80\x78"  # Display on then delay 0x78 (120ms)
+)
+
+display = displayio.Display(display_bus, _INIT_SEQUENCE, width=320, height=240)
+
+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_QVGA,
+)
+
+cam.flip_x = False
+cam.flip_y = True
+pid = cam.product_id
+ver = cam.product_version
+print(f"Detected pid={pid:x} ver={ver:x}")
+# cam.test_pattern = True
+
+bitmap = displayio.Bitmap(320, 240, 65536)
+
+display.auto_refresh = False
+
+sd_spi = busio.SPI(clock=board.IO18, MOSI=board.IO14, MISO=board.IO17)
+sd_cs = board.IO12
+sdcard = sdcardio.SDCard(sd_spi, sd_cs)
+vfs = storage.VfsFat(sdcard)
+storage.mount(vfs, "/sd")
+
+
+def exists(filename):
+    try:
+        os.stat(filename)
+        return True
+    except OSError as e:
+        return False
+
+
+_image_counter = 0
+
+
+def open_next_image():
+    global _image_counter
+    while True:
+        filename = f"/sd/img{_image_counter:04d}.jpg"
+        _image_counter += 1
+        if exists(filename):
+            continue
+        print("#", filename)
+        return open(filename, "wb")
+
+
+def capture_image():
+    old_size = cam.size
+    old_colorspace = cam.colorspace
+    exposure = cam.exposure
+    try:
+        cam.size = adafruit_ov2640.OV2640_SIZE_UXGA
+        cam.colorspace = adafruit_ov2640.OV2640_COLOR_JPEG
+        cam.exposure = exposure
+        b = bytearray(cam.capture_buffer_size)
+        jpeg = cam.capture(b)
+
+        print(f"Captured {len(jpeg)} bytes of jpeg data")
+        with open_next_image() as f:
+            f.write(jpeg)
+    finally:
+        cam.size = old_size
+        cam.colorspace = old_colorspace
+        cam.exposure = exposure
+
+
+def main():
+    display.auto_refresh = False
+    display_bus.send(42, struct.pack(">hh", 0, 319))
+    display_bus.send(43, struct.pack(">hh", 0, 239))
+    t0 = time.monotonic_ns()
+    while True:
+        a_voltage = a.value * a.reference_voltage / 65535
+        record_pressed = abs(a_voltage - V_RECORD) < 0.05
+        if record_pressed:
+            capture_image()
+        cam.capture(bitmap)
+        display_bus.send(44, bitmap)
+        t1 = time.monotonic_ns()
+        print(1e9 / (t1 - t0), "fps")
+        t0 = t1
+        # bitmap.dirty()
+        # display.refresh(minimum_frames_per_second=0)
+
+
+main()