Purchased a $22 HDMI switcher with picture-in-picture. It came with a power brick and an IR remote.
Pretty amazing, considering that these used to be > $1000 not that long ago...
Taking a look inside, it's based around a Silicon Image (now Lattice) SiI9687A, with a small STM8S00 SK6T6C MCU, and some discretes, connectors & two VRs.
The specs for the device say full 4K HDMI, but the chip specifications only support 4K at 4:2:0. Not too bad.
The MCU communicates via I2C. The 9687A comes with "pre-programmed HDCP keys and Key Selection Vector (KSV) stored in the on-chip non-volatile memory”, according to the data sheet. Has quite a few features that can be controlled over I2C, but the "Programmer's Reference" isn't as easy to find... Of course, the basic functions could easily be sniffed off the bus.
HDMI is such a ground loop disaster. I’ve actually seen someone draw an arc off the shield when plugging in an HDMI connector.
It's amazing that they actually can make a profit off this for $22. Take a look at the mis-alignment of this SMT transistor. Wonder what their rework percentage is fresh off the line...
No EMI gasket on the metal enclosure, so I’ll bet this doesn’t pass Part 15.
Can’t say that I’m anywhere near as impressed with the power brick that came with the HDMI switcher:
Got to love that PCB-trace “fuse”. At least they have a fairly wide isolation between AC/HVDC/LVDC. Looks like they’re taking line AC & putting it through a bridge rectifier. At 240V in, they’re dealing with almost 350 volts DC on this PCB! At least the cap immediately after the bridge rectifier is rated for 400V.
Looking inside these cheap power bricks always makes me nervous.