class DisplayData – Display Data

The DisplayData class provides access to the side-channel links of an attached HDMI / DisplayPort display:

  • DDC (Display Data Channel) is an I2C bus that carries the display’s EDID – a structured block describing the panel capabilities (manufacturer, supported resolutions and refresh rates, colour and audio formats, …). Source devices query it once at startup to discover what the sink supports.

  • CEC (Consumer Electronics Control) is a single-wire bidirectional bus that lets connected HDMI / DisplayPort devices exchange short control packets – power on/off, input switching, volume, remote-control forwarding, etc.

Either or both channels can be enabled at construction. The raw EDID is read with display_id(); CEC frames can be sent with send_frame(), polled synchronously via receive_frame(), or routed to a callback with frame_callback().

Example – query the connected display’s EDID and listen for CEC frames addressed to logical address 0:

import display

data = display.DisplayData(cec=True, ddc=True)

# Read the EDID once at startup.
edid = data.display_id()
print("EDID:", edid)

def on_frame(src, payload):
    print("CEC from {:#x}: {}".format(src, payload))

data.frame_callback(on_frame, 0)

Constructors

class display.DisplayData(*, cec: bool = False, ddc: bool = False, ddc_addr: int = 0x50)

cec set to True to enable CEC communication with an external display.

ddc set to True to enable DDC communication with an external display.

ddc_addr I2C address of the external display EEPROM.

display_id() → bytes

Returns the external display EDID data as a bytes object. EDID headers and checksums are verified and all sections are concatenated into a single bytes object. Raises OSError on failure.

send_frame(dst_addr: int, src_addr: int, data: bytes) → None

Sends a CEC frame to dst_addr from src_addr containing data. Raises OSError on failure.

receive_frame(dst_addr: int, *, timeout: int = 1000) → tuple[int, bytes]

Waits up to timeout milliseconds for a CEC frame addressed to dst_addr. Returns a tuple of (src_addr, data). Raises OSError on timeout or failure.

frame_callback(callback: Callable[[int, bytes], None] | None, dst_addr: int) → None

Registers callback to be called when a CEC frame addressed to dst_addr is received. The callback is invoked with two arguments: the source address as an int and the frame payload as a bytes object.

Pass None as callback to disable reception. While a callback is registered, do not call DisplayData.receive_frame().