class TVDisplay – TV Shield Driver

The TVDisplay class drives the OpenMV TV Shield, which converts an RGB565 framebuffer into an NTSC composite video signal (352x240, 60 fields/s interlaced) suitable for any television or analog video monitor.

Two shield variants are supported:

  • The wired TV Shield, which exposes the composite signal on a single RCA jack.

  • The Wireless TV Shield, which feeds the same signal into a 2.4 GHz analog video transmitter. The receiver channel (1–8) is selected at runtime via ioctl() with display.IOCTL_CHANNEL; until that call is made no channel is selected.

Resolution and framing are fixed – TVDisplay does not take a framesize argument. Frames are presented by passing an image.Image to write(), which handles scaling, ROI, palette and orientation transforms internally.

Example usage:

import csi
import display

csi0 = csi.CSI()
csi0.reset()
csi0.pixformat(csi.RGB565)
csi0.framesize(csi.SIF)              # 352x240, matches the TV output

tv = display.TVDisplay()

while True:
    tv.write(csi0.snapshot())

Constructors

class display.TVDisplay(triple_buffer: bool = True)

triple_buffer If True then makes updates to the screen non-blocking at the cost of 3X the display size in RAM. The default is board-dependent.

deinit() → None

Releases the I/O pins and RAM used by the class. This is called automatically on destruction.

width() → int

Returns the width of the screen (352).

height() → int

Returns the height of the screen (240).

refresh() → int

Returns the refresh rate (60).

triple_buffer() → bool

Returns if triple buffering is enabled.

write(image: image.Image, x: int = 0, y: int = 0, x_scale: float = 1.0, y_scale: float = 1.0, roi: Tuple[int, int, int, int] | None = None, rgb_channel: int = -1, alpha: int = 256, color_palette: int | 'image.Image' | None = None, alpha_palette: 'image.Image' | None = None, hint: int = 0) → None

Displays an image whose top-left corner starts at location x, y.

x_scale controls how much the displayed image is scaled by in the x direction (float). If this value is negative the image will be flipped horizontally.

y_scale controls how much the displayed image is scaled by in the y direction (float). If this value is negative the image will be flipped vertically.

roi is the region-of-interest rectangle tuple (x, y, w, h) of the image to display.

rgb_channel is the RGB channel (0=R, G=1, B=2) to extract from an RGB565 image and render on the display.

alpha controls how opaque the image is. A value of 256 displays an opaque image while a value lower than 256 produces a black transparent image. 0 results in a perfectly black image.

color_palette if not -1 can be a color palette enum or a 256 pixel in total RGB565 image to use as a color lookup table on the grayscale value of the input image.

alpha_palette if not -1 can be a 256 pixel in total GRAYSCALE image to use as an alpha palette which modulates the alpha value of the input image at a per-pixel level.

hint logical OR of the flags:

clear(display_off: bool = False) → None

Clears the screen to black.

display_off is accepted for API compatibility with other display classes and is ignored.

ioctl(cmd: int, *args) → object

Generic ioctl entry point.

Pass display.IOCTL_CHANNEL as cmd to set or get the wireless TV shield broadcast channel. With a second argument (1-8) the channel is set; with no second argument the current channel is returned. No channel is selected until the first set call is made.