Wednesday, November 6, 2013
For some work developing HDMI-compatible FPGA code, I needed to observe the control signals with a scope. So I built up this little breakout PCB. The high-speed video TMDS signals are routed directly through from one connector to the other. I tried to keep them equal length and as short as possible. Don't have any way to verify impedance and reflections, but it works ok on one TV with short HDMI cables.
The low speed (CEC, SCL, etc) signals are brought out to the header in the back in the photo. Jumpers allow the signals to pass through, or they can be disconnected to test and modify them.
The PCB is shared on OshPark. See http://oshpark.com/profiles/sensicomm if you want to use this design. It uses standard HDMI female connectors, available from DigiKey and many other vendors. Soldering the fine-pitch surface mount pins on the connectors is a bit of a challenge. I tried soldering individual pins, but ended up using the flood it with solder and mop up the excess with solder-wick method.