---
# System prepended metadata

title: 'Design: Beam Test 2 Board'
tags: [Design, DeWei]

---

## 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
