LCD Shield
==========

The LCD Shield is a 1.8 inch 128x160 SPI TFT for showing live frames or debugging information directly from the OpenMV Cam. Ideal for field robotics and stand-alone deployments.

.. image:: ../lcd-shield-hero.jpg
    :alt: LCD Shield
    :width: 400px
    :align: center

For full datasheet, photos, and ordering see the
`LCD Shield product page <https://openmv.io/products/lcd-shield>`_.

Highlights
----------

* 1.8 inch TFT LCD, 128x160, RGB565
* Controllable backlight

Pinout
------

.. image:: ../pinout-lcd-shield.png
    :alt: LCD Shield Pinout
    :width: 700px

Pin reference
-------------

.. csv-table::
   :header: "Pin", "Function"
   :widths: 20, 80

   "P0",        "SPI MOSI — data out to the LCD"
   "P2",        "SPI clock"
   "P3",        "SPI chip select"
   "P5",        "Backlight control"
   "P7",        "LCD reset"
   "P8",        "SPI command (data / command select)"
   "3.3V rail", "Powers the LCD"
   "GND rail",  "Common ground"

.. note::

   Cut the solder trace on the back of the shield to disconnect P5
   from the backlight; the backlight is then permanently on.

Usage
-----

Stream camera frames to the 128×160 SPI display::

    import csi
    import display
    import image
    import time

    csi0 = csi.CSI()
    csi0.reset()
    csi0.pixformat(csi.RGB565)
    csi0.framesize((128, 160))

    lcd = display.SPIDisplay()
    clock = time.clock()

    while True:
        clock.tick()
        lcd.write(csi0.snapshot(), hint=image.CENTER | image.SCALE_ASPECT_KEEP)
        print(clock.fps())

Drive the backlight via PWM for adjustable brightness. Wrap
:class:`machine.PWM` in a small backlight controller class and pass
it to :class:`display.SPIDisplay` through its ``backlight`` argument —
:class:`~display.SPIDisplay` calls ``backlight(value)`` on the object
whenever it needs to update the level::

    import csi
    import time
    import display
    import image
    from machine import Pin, PWM


    class PWMBacklight:
        """Drives a backlight pin with machine.PWM (0–100 %)."""

        def __init__(self, pin, frequency=200):
            self._pwm = PWM(Pin(pin), freq=frequency, duty_u16=0)

        def backlight(self, value):
            self._pwm.duty_u16(int(value * 65535 / 100))

        def deinit(self):
            self._pwm.deinit()


    csi0 = csi.CSI()
    csi0.reset()
    csi0.pixformat(csi.RGB565)
    csi0.framesize((128, 160))

    lcd = display.SPIDisplay(backlight=PWMBacklight("P5"))
    lcd.backlight(50)  # 0–100
    clock = time.clock()

    while True:
        clock.tick()
        lcd.write(csi0.snapshot(), hint=image.CENTER | image.SCALE_ASPECT_KEEP)
        print(clock.fps())