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2023-05-12 18:04:56 -07:00

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# Oresat CFC Mini-Backplane
This is the backplane for UMBC's Air Harp 2 sensor, which is going to include a PIRT SWIR sensor using OreSat's CFC system.
## Requirements:
* Match the DXF outline from Joe, including placement of connectors and the fastener holes.
* Probably remove solder mask from both sides of those fastener holes just in case.
* Probably put the external connectors in the upper right hand corner.
* Use an OreSat 20 pin debug connector on this backplane so we can run USB from the CFC processor to the external connector using the CFC processor's debug connector.
* External connections
* Power should come through a 0.2 inch euroterminal for two 20 AWG wires.
* USB should be via a [Harwin M80-5400442](https://www.digikey.com/en/products/detail/harwin-inc/M80-5400442/4953167) connector. Pin-out is determined by us.
* signals: USB D+, USB D-, Vbus, and GND.
* Vbus should go through a 10k ohm resistor between the 20 pin debug connector and the Harwin connector.
## Required changes to the CFC Processor and CFC sensor boards
Easiest thing to do:
* Both OPDs should come on by default, so we need to bypass or hack the OPDs to turn on.
* We may want to figure out some way to power the local OPDs so they're not doing anything weird with their connections to the Octavo.
A Ben Idea:
* Add a 8.4V to 5V LDO, a Trinket M0, two 4.7K resistors, and use Oliver Rew's Arduino code to turn on both CFC cards
* This assumes we have Trinkets, which I believe we have a bunch lying around.
* This is cute because we don't have to modify the sensor or processor card, which I hate doing.
* Be careful of the 8.4V max input voltage can power the trinket without frying it (thus the 5V LDO).