esp32-camera: make the master_clock_pin really optional

[deshipu]

The master_clock_pin was already optional, but not specifying it would result in a crash. This fixes it, so it really can be omitted, when the camera module has its own clock source built in.

[deshipu]

To test this with a module that doesn't have a crystal, you can create the PWMOut yourself before creating the camera:

import board
import displayio
import adafruit_ili9341
import busio
import digitalio
import esp32_camera
import pwmio


displayio.release_displays()
display_bus = displayio.FourWire(
    busio.SPI(clock=board.IO7, MOSI=board.IO5),
    command=board.IO9,
    chip_select=board.IO3,
    baudrate=80_000_000,
)
display = adafruit_ili9341.ILI9341(
    display_bus,
    width=320,
    height=240,
)

pwm = pwmio.PWMOut(board.IO11, frequency=20_000_000)
pwm.duty_cycle = 65536//2

i2c = busio.I2C(scl=board.IO35, sda=board.IO33)
data_pins = (
    board.IO21, board.IO17, board.IO16, board.IO18,
    board.IO37, board.IO34, board.IO36, board.IO39,
)
c = esp32_camera.Camera(
    data_pins=data_pins,
#    external_clock_pin=board.IO11,
    pixel_clock_pin=board.IO12,
    vsync_pin=board.IO40,
    href_pin=board.IO38,
    pixel_format=esp32_camera.PixelFormat.RGB565,
    frame_size=esp32_camera.FrameSize.QVGA,
    i2c=i2c,
#    external_clock_frequency=20_000_000,
)

g = displayio.Group()
bitmap = None
while not bitmap:
    bitmap = c.take()
shader = displayio.ColorConverter(
    input_colorspace=displayio.Colorspace.BGR565_SWAPPED
)
tg = displayio.TileGrid(bitmap, pixel_shader=shader)
g.append(tg)
display.show(g)
display.auto_refresh = False
while True:
    bitmap = c.take()
    tg.x = 1 # make the grid dirty
    tg.x = 0
    display.refresh()

[dhalbert]

There are more files than I would expect to have changed in the changes for the esp32-camera submodule. Your PR to that changed only one file, I think.

[deshipu]

That is because the circuitpython branch contains all those changes, with my commit only being added on top of that. The current submodule points at a specific commit in the circuitpython branch, and I don't see any way of adding only my commit to it. Do you know if something like that is possible?

[deshipu]

On the other hand, I don't see those changes breaking anything, so maybe I could make a separate PR bringing the submodule to the commit just before my commit, and you could merge that first?

[dhalbert]

Ah, I see, #2 brought in a bunch of upstream changes, but the circuitpython repo didn't pick those up. Sorry, it's fine, then.

[dhalbert]

sounds good!