Custom OPT8241 adapter board have been assembled. Those ф=220um BGA packages are hell to assemble. I have integrated all power supplies on board, so I can run it on single 5V adapter with FPGA board.

Left to right - unassembled board, board for power supply tests and fully assembled board. Compared to an AAA battery.

My PRECIOUS!!!!

Next step is connect to DE0-Nano-SoC. OPT8241 i2c register map is not public thought :( (but I have a backup plan)