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# BUTCube
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Modules:
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- Solar panels (XY, Z) (not in stack)
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- EPS
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- Flight Computer
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- Mission computer
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- Communication
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- Sun sensor module (not in stack)
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- ? Attitude control
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- Access port module (not in stack)
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# Solar panels
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## Solar cells
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#### SM141K04L
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- Link: https://www.digikey.nl/short/fvpwbf4h
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- Panel count: 8 (2S 4P)
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- Maximal power: 0.98 W
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- Voltage: 4.46 V (MPPT)
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- Dimensions: 29 x 23 mm
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- Weight: 3g (24g)
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- Price (for 1 side): 28 € (750 CZK)
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#### SM141K04LV
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- Link: https://www.digikey.cz/short/r589mmbj
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- Panel count: 8 (2S 4P)
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- Maximal power: 0.98 W
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- Voltage: 4.46 V (MPPT)
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- Dimensions: 45 x 15 mm
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- Weight: 2.5g (20g)
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- Price (for 1 side): 28 € (750 CZK)
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## Solar module
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- Two sizes of solar panel PCBs
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- Z - 100x100 mm with cutouts in corners for rails
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- X,Y - 100x83
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- In center of module is hole for another module
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- Approximate size of module is 46x30 mm
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- Mounting to frame is via 4 bolts in corners of board
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- Integrated components: Optodiode, temperature measuring IC
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## Sensors
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- Temperature sensor: AT30TS74
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- Photo diode:
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- VEMD5510C - 550nm (450-750) - visible
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- VEMD5060X - 800nm (500-1000) - visible + IR
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- VEMD5160X - 850nm (750-950) - IR (used)
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- ADC for photodiode: ADS7142
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# Cables
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- https://www.digikey.cz/product-detail/en/adafruit-industries-llc/3165/1528-1733-ND/6193585
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- https://www.digikey.cz/product-detail/en/adafruit-industries-llc/3167/1528-1735-ND/6193587
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- https://www.digikey.cz/product-detail/en/adafruit-industries-llc/3168/1528-1736-ND/6193588
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- https://www.digikey.cz/product-detail/en/adafruit-industries-llc/3164/1528-1732-ND/6193584
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- 30AWG resistance 0.3R per meter
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- Length in CubeSat cca 10-15 cm
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- Power loss in cables is 0.5mW in peek (0.05% per solar module)
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- Similar power loss will be at cable connectors
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# Stack connector
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- [https://cz.mouser.com/ProductDetail/200-SSQ12002TD]
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- 2x20 pins
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- Limits board to thickness of 1mm or less
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- Board spacing: 8.51 mm
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# EPS
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- Two identical modules on one board
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- Both connected to stack connector
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- Other board could be connected to both or one of then
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- Power oring must be solved
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- Connected to main CAN
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## Power output
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- 3 regulated and monitored power rails - 1V8, 3V3, 5V
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- Output regulator - TPS63002DRCR
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- 0.8A (boost) up to 1.2A (buck) output
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- 2.2 uH coil
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- 1 unregulated output of battery, monitored
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- Monitoring via current sensors (INA??)
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## Battery
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- Limit for CubeSat is 50Wh
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- Suggested battery has form factor 21700
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- One battery per EPS
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- Battery is mounted in battery holder
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- Keystone 1122 - 1122
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- Probably additional fixation is requested
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- Selected battery - https://www.conrad.cz/p/samsung-inr21700-50e-specialni-akumulator-21700-flat-top-li-ion-akumulator-36-v-4900-mah-2114678
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- 3.6V, 4900mAh, 17.64Wh
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- EPS module has around 35Wh (well in limit)
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## Battery heating
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- https://www.ges.cz/cz/odl-20r81-GES06914579.html
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- https://www.ges.cz/cz/odl-53r1-GES06914581.html
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- https://www.gme.cz/odporovy-drat-odp-kan02-3m
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- https://www.gme.cz/odporovy-drat-odp-kon03-3m
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- Heating should be designed for power around 1-4W
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- With 5.4R/m and battery input source (3.7V) length of wire for 2W heating should be around 1.2m (current 0.5A)
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- 0.5A is probably to much, values around 0.2A are better -> 1W heating
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- For regulation could be used power switch with constant current regulation
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# Access port module
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Connectors:
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- USB-C
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- data connected to mission computer or flight computer
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- power connected to EPS for battery charging
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- 2x SWD port for programing and debugging of Flight and Mission computer
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- main CAN bus connector
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- UART debug port
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- Realized as stack of two PCB boards
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- Front acts only as cover for connectors
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- Connectors are mounted on rear board
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- Connectors are accessible via cutouts in frontz board
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- Rear board is mounted to front via column spacers
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# Other parts:
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- LTC4415 - Dual ideal diode with ORing
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- MAX16171 - Ideal Diode Controller with Reverse-Current Protection
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- BQ25798 - solar battery charger with dual-input selector and MPPT, I2C, https://www.ti.com/product/BQ25798
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- BAT54W-G - Low drop shottky diode, solar blocking diode
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- BQ27421YZFT-G1A - Fuel gauge
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# Digikey orders
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https://www.digikey.cz/short/8nmn4tr3
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https://www.digikey.cz/short/d4n94tbz
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