2.5 HPD Snoop Option
To accommodate systems that do not properly resend DDC commands after HPD goes low, we have
implemented an HPD snoop mode on the TMDS1204 EVM. This mode allows the HPD line to be routed around
the TMDS1204, but remain connected to the TMDS1204 on the sink side to allow the TMDS1204 to snoop its
state.
• Populate R131, no populate R129 for HPD on
• No populate R131, populate R129 for HPD snoop-only
2.6 Local I2C Access
Access to TMDS1204s local I2C signals is provided through the J5 connector. The TMDS1204 supports either
1.2 V, 1.8, and 3.3 V LVCMOS levels. The TMDS1204 VIO pin is used to select which voltage level is used for
the following 2-level control pins: SCL/CFG0 and SDA/CFG1. It is important that the I2C signalling levels meet
the TMDS1204 LVCMOS levels when I2C interface is accessed through the connector.
A standalone external I2C host can be connected through J5 for debug and control purposes. An example of an
external I2C Host controller is the Total Phase Aardvark I2C/SPI Host Adapter (Total Phase Part#: TP240141).
Sample scripts for this I2C host controller are provided by request.
The target I2C address for the TMDS1204 can be modified by the EVM jumper JMP8. Please refer to the
TMDS1204 ADR/EQ pin setting and its corresponding I2C address. Refer to TMDS1204 data sheet for the 7-bit
I2C target address options.
Table 2-4. Aardvark I2C (J5) Pinout
J5 pin #
Description
J5 pin #
Description
1
SCL_CTL
2
GND
3
SDA_CTL
4
NC
5
NC
6
NC
7
NC
8
NC
9
NC
10
GND
3 Quick Start Guide
The following instructions assume the EVM is configured for pin-strap mode and is powered from barrel jack. To
start the EVM, do the following:
1. Insert the +5 V DC power source into the barrel jack. Turn on SW2.
2. If using external I2C configuration instead of pin-straps, then please configure TMDS1204 at this step.
3. Insert an HDMI source using a standard HDMI cable into P1 (HDMI receptacle).
4. Insert an HDMI video sink into P2 (HDMI receptacle) using a standard HDMI cable.
5. Video output on HDMI sink should be observed.
Hardware Configuration
6
TMDS1204 EVM User's Guide
SLLU341 – JULY 2022
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