The C3 ("Command, Control, and Communications") card is the main on-board computer (OBC) / housekeeping unit (HKU) / Command and Data Handling (CDH) subsystem for the open source OreSat CubeSat system. The C3 card:

Connects to the backplane with a main connector and two RF ports
Has an L band radio receiver based on the AT86RF215.
Has a UHF radio transceiver based on the AT86RF215
Has a radiation tolerant watchdog timer (with a cheap commercial replacement if you're not going to orbit)
Controls the OreSat Power Domain (OPD), which turns on and off and controls other cards
Talks to both CAN OreSat CAN busses

Documentation Links

C3 hardware Git repository: https://github.com/oresat/oresat-c3-hardware
C3 software Git reposity: https://github.com/oresat/oresat-c3-software
TODO: C3 Design Notes + Design Review Notes

Documentation Files

Filename	Notes
README.pdf	This README file
PROJECT-NAME-outline.dxf	Board outline (with holes) in DXF format
PROJECT-NAME-pcba.step	3D model of PCBA (with components)
PROJECT-NAME-render-bot.jpg	Render of the top of the 3D model
PROJECT-NAME-render-bot.jpg	Render of the bottom of the 3D model
PROJECT-NAME-schematic.pdf	PDF of board schematics

Contact Information

Website: https://www.oresat.org/
Email: oresat@pdx.edu
Instagram: @pdxaerospace

Board Renders

{width=50%} {width=50%}

\newpage

Printed Circuit Board (PCB) Fabrication Information

Board Info

4 layer board
Bounding box is 99.8 x 94.6 mm (3.93 x 3.72 in)
Board thickness is 1.59 mm (0.063 inch)
Important: See Materials and Stack Up sections below

Board Requirements

Design Rules
- Minimum Trace / Space design rules
  - Outer layers: 0.127 mm (5.0 mil) / 0.127 mm (5.0 mil)
  - Inner layers: 0.127 mm (5.0 mil) / 0.127 mm (5.0 mil)
- Outer dimension router tolerance: +/- 0.254 mm (10.0 mil)
- Hole placement tolerance: +/- 0.075 mm (3.0 mil)
- Inner tab routed slot tolerance: +/- 0.254 mm (10.0 mil)
Drills
- Drill Positional Tolerance: 0.051 mm (2.0 mil)
- Drill Size tolerance: +/- 0.064 mm (2.5 mil)
Plated/Un-plated holes
- There are 6 un-plated (NPT) holes
- There are 1477 plated through (PTH) holes
- PTH minimum diameter: 0.254 mm (10 mil)
- PTH minimum annulus: 0.102 mm (4 mil) radius
Outline/Routing
- Requires a 1.0 mm or smaller diameter routing bit
Slots
- There are no slots.
Cutouts
- There are no cutouts
There are 3 fiducials on the top layer.
Panel tabs ("mouse bites")
- Card edges must be smooth; no mouse bites or other intrusions into the card outline.
- If external mouse bites are required, minimize and customer will remove by hand before assembly.
If not otherwise specified, build to IPC 6012 Class 2 or better.

Materials

Controlled impedance
- The stackup is critical for the performance of high speed signals on this board.
- As long as the stackup is controlled, the board is not considered controlled impedance.
Isola FR408HR or material with equivalent Dk.
Board Surface treatment should be ENIG, althogh immersion Silver is acceptable.
White silkscreen on top and bottom surface
Taiyo PSR-4000 or equivalent soldermask on top and bottom, no requirements for color.

Stack Up

Layer	Thickness	Notes
Top Copper	0.043 mm / 1.7 mil	Layer 1 foil, 1 oz Cu after plating
prepreg	0.200 mm / 7.9 mil	Prepreg - Isola FR408HR 2113
Layer 2	0.018 mm / 0.7 mil	Layer 2 foil, 0.5 oz Cu
Core	0.991 mm / 39 mil	Core Isola FR408HR
Layer 3	0.018 mm / 0.7 mil	Layer 3 foil, 0.5 oz Cu
prepreg	0.200 mm / 7.9 mil	Prepreg - Isola FR408HR 2113
Bottom Copper	0.043 mm / 1.7 mil	Layer 4 foil, 1 oz copper after plating
Total Stackup	1.588 mm / 62.5 mil

Array / Panel Information

Coordinate with Contract Manufacturer (CM) for optimal size of this panel.
If no feedback from CM, then produce single boards (no panel).

Fabrication Files

IPC-2581 File

Filename	Notes
PROJECT-NAME-ipc2581.xml	IPC-2581 board information file

Legacy PCB Files

Filename	Notes
PROJECT-NAME-Edge_Cuts.gbr	RS274X file for the dimension (outline) layer
PROJECT-NAME-F_Silkscreen.gbr	RS274X file for the top silkscreen
PROJECT-NAME-F_Mask.gbr	RS274X file for the top soldermask
PROJECT-NAME-F_Cu.gbr	RS274X file for the top copper layer
PROJECT-NAME-In1_Cu.gbr	RS274X file for the layer 2 copper
PROJECT-NAME-In2_Cu.gbr	RS274X file for the layer 3 copper
PROJECT-NAME-B_Cu.gbr	RS274X file for the bottom copper layer
PROJECT-NAME-B_Mask.gbr	RS274X file for the bottom soldermask
PROJECT-NAME-B_Silkscreen.gbr	RS274X file for the bottom silkscreen
PROJECT-NAME-NPTH.drl	Excellon file for non-plated through holes
PROJECT-NAME-PTH.drl	Excellon file for plated through holes

\newpage

Printed Circuit Board Assembly (PCBA) Information

Assembly Info

All components are on the top side of the board.
This PCBA is mostly surface mount (SMT) with a few (THT) components.

Assembly Requirements

Assemble to IPC Class 2 or better
Bake components that are not moisture sealed to appropriate levels as required.
Solder paste MUST be leaded.
Aqueous flux and wash strongly preferred.
- Clean to NASA Standard "Visibly Clean (VC)": No particles or residues are visible to the naked eye.
No conformal coating.
Ship in antistatic protective bag

Component Specific Assembly Information

SMPM connectors (J3, J4) should be hand-added (there is no solder paste for their footprints).
U1 and U28 are extremely expensive ($75 and $150 ea, respectively).
U15 and U21 are EOL and will be supplied in cut tape form.

Assembly Files

IPC-2581 File

Filename	Notes
PROJECT-NAME-ipc2581.xml	IPC-2581 board information file

Bill of Materials (BOM)

Filename	Description
PROJECT-NAME-bom.csv	BOM in Comma Separated Variable format

Solder Paste Stencils

Filename	Notes
PROJECT-NAME-B_Paste.gbr	RS274X file for top/front solder paste stencil
PROJECT-NAME-F_Paste.gbr	RS274X file for bottom/back solder paste stencil

Mounting/Placement Location

Filename	Description
PROJECT-NAME-3u.pos	Pick and place locations for components