## Consensus * MB board and Sub board * MB: Interconnect board * 110AC -> 5V(PI), 5V(Analog), ~~-5V(Reverse Bias of PD)~~ * [MPM05-5](https://www.mouser.tw/ProductDetail/MEAN-WELL/MPM-05-5?qs=xhbEVWpZdWcU8L2mtB5tIQ%3D%3D) * [MPM20-5](https://www.mouser.tw/ProductDetail/MEAN-WELL/MPM-20-5?qs=wd5RIQLrsJhLy6m2%252BvI%2F%2Fw%3D%3D) * 4 unisolated SPI buffer * USB-A supplied for PI4 * [Can Pi 4 be powered through GPIO pins? ](https://forums.raspberrypi.com/viewtopic.php?t=248280) * [Back Powering the Pi via the GPIO Header](https://github.com/raspberrypi/hats/blob/master/designguide.md#back-powering-the-pi-via-the-gpio-header) * ![](https://raw.githubusercontent.com/raspberrypi/hats/master/backpowering-diagram.png) * Sub: PD fornt-ene and ADC board * 16 PD channels * Analog Vcc: 5V -> 3.3V * Fixed PD resistor: 100M or 200M * Make 2 board for these 2 type * 1 isolated SPI buffer (4 boards) * Connect MB and Sub with *VGA* cable * [Cable](https://24h.pchome.com.tw/prod/DCACV6-A9008T0XD) * Screw Sub boards on panel * Need to design panel * Speed up SPI bus: 1M -> 10M (clock) * Need to test ## Dissensus * Reverse bias can be removed, see [here](https://hackmd.io/UwS9hF7XS0qMJhsoVnYbEg?view#3-Reverse-bias-of-Photodiode-Maybe-is-not-necessary) * Powering path for PI and IO buffers * Involve noise of power and whether supplied current is enough