UPSD3254 STMICROELECTRONICS [STMicroelectronics], UPSD3254 Datasheet - Page 86

• Manufacturer Part Number: UPSD3254
• Description: Flash Programmable System Devices with 8032 Microcontroller Core
• Manufacturer: STMICROELECTRONICS [STMicroelectronics]

UPSD3254A, UPSD3254BV, UPSD3253B, UPSD3253BV
Host Type Detection
The detection procedure conforms to the se-
quences proposed by VESA Monitor Display Data
Channel (DDC) specification. The monitor needs
to determine the type of host system:
Figure 41. Host Type Detection
86/175
Power on
EDID sent continously using
Is VSYNC present?
Stop sending of EDID
communication mode
DDC2B command
Is it DDC2B
command?
VSYNC as clock
Is DDC2 clock
switch to DDC2
Communication
Respond to
present?
isidle
DDC1 or OLD type host.
DDC2B host (Host is master, monitor is always
slave)
DDC2B+/DDC2AB(ACCESS.bus) host.
command detected?
DDC2B+/DDC2AB?
DDC2 communication
Respond to DDC2B+/
Has a command
DDC2AB command
been received?
Is 2B+/A.B
is idle.
Is
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