notes: update notes with design of EPS

README.md

@@ -1,57 +1,42 @@
 # BUTCube
+Modules:
+- Solar panels (XY, Z) (not in stack)
+- EPS
+- Flight Computer
+- Mission computer
+- Communication
+- Sun sensor module (not in stack)
+- ? Attitude control
+- Access port module (not in stack)
 
-# Solar cells
-
-Digi-key filter: https://www.digikey.nl/products/en?FV=-5|23585
-
-Calculations for space are calculated with 1 mm space between panels
-In center of panel there should be attitude determination module with minimal size od 25mm x 25mm
-All calculation are only for one side of satelite
+# Solar panels
 
+## Solar cells
 #### SM141K04L
 - Link: https://www.digikey.nl/short/fvpwbf4h
-- Panel count: 10 (2S 5P)
-- Maximal power: 1.23 W
-- Voltage: 4.46 V
-- Dimensions: 29 x 23 mm (89 x 95 mm)
-- Weight: 3g (30g)
-- Configuration: 4 x 3 
-- Price (for 1 side): 28 € (750 CZK)
-
-#### KXOB25-05X3F
-- Link: https://www.digikey.nl/short/hdrrmtq3
-- Panel count: 32 (4S 8P)
+- Panel count: 8 (2S 4P)
 - Maximal power: 0.98 W
-- Voltage: 6.68 V
-- Dimensions: 23 x 8 mm (95 x 89 mm)
-- Weight: 0.5g (17g)
-- Configuration: 10 x 4
-- Price (for 1 side): 47 € (1229 CZK)
-- + Reflow solderable
-
-#### SM141K06LV
-- Link: https://www.digikey.nl/short/d80rrj7t
-- Panel count: 6 (2S 3P)
-- Maximal power: 1.10 W
-- Voltage: 6.7 V
-- Dimensions: 45 x 22 mm (91 x 91 mm)
-- Weight: 3g (18g)
-- Configuration: 2V 2H 2V
-- Price (for 1 side): 27 € (720 CZK)
+- Voltage: 4.46 V (MPPT)
+- Dimensions: 29 x 23 mm
+- Weight: 3g (24g)
+- Price (for 1 side): 28 € (750 CZK)
 
 #### SM141K04LV
 - Link: https://www.digikey.cz/short/r589mmbj
 - Panel count: 8 (2S 4P)
 - Maximal power: 0.98 W
-- Voltage: 5.52 V
-- Dimensions: 45 x 15 mm (81 x 95 mm)
+- Voltage: 4.46 V (MPPT)
+- Dimensions: 45 x 15 mm
 - Weight: 2.5g (20g)
-- Configuration: 2V 4H 2V
 - Price (for 1 side): 28 € (750 CZK)
 
 ## Solar module 
-- PCB with size cca 96x96 mm
-- In center of module is hole for another module (40x40 mm without corners)
+- Two sizes of solar panel PCBs
+    - Z - 100x100 mm with cutouts in corners for rails
+    - X,Y - 100x83
+- In center of module is hole for another module
+    - Approximate size of module is 46x30 mm
+    - Mounting to frame is via 4 bolts in corners of board
 - Integrated components: Optodiode, temperature measuring IC
 
 ## Sensors
@@ -59,15 +44,85 @@ All calculation are only for one side of satelite
 - Photo diode: 
     - VEMD5510C - 550nm (450-750)  - visible
     - VEMD5060X - 800nm (500-1000) - visible + IR
-    - VEMD5160X - 850nm (750-950)  - IR
+    - VEMD5160X - 850nm (750-950)  - IR (used)
 - ADC for photodiode: ADS7142
 
+# Cables
+- https://www.digikey.cz/product-detail/en/adafruit-industries-llc/3165/1528-1733-ND/6193585
+- https://www.digikey.cz/product-detail/en/adafruit-industries-llc/3167/1528-1735-ND/6193587
+- https://www.digikey.cz/product-detail/en/adafruit-industries-llc/3168/1528-1736-ND/6193588
+- https://www.digikey.cz/product-detail/en/adafruit-industries-llc/3164/1528-1732-ND/6193584
+
+- 30AWG resistance 0.3R per meter
+- Length in CubeSat cca 10-15 cm
+- Power loss in cables is 0.5mW in peek (0.05% per solar module)
+- Similar power loss will be at cable connectors
+
+# Stack connector
+- [https://cz.mouser.com/ProductDetail/200-SSQ12002TD]
+- 2x20 pins
+- Limits board to thickness of 1mm or less
+- Board spacing: 8.51 mm
+
+# EPS
+- Two identical modules on one board
+- Both connected to stack connector
+- Other board could be connected to both or one of then
+    - Power oring must be solved
+- Connected to main CAN
+
+## Power output
+- 3 regulated and monitored power rails - 1V8, 3V3, 5V
+    - Output regulator - TPS63002DRCR
+    - 0.8A (boost) up to 1.2A (buck) output
+    - 2.2 uH coil
+- 1 unregulated output of battery, monitored
+- Monitoring via current sensors (INA??)
+
+## Battery
+- Limit for CubeSat is 50Wh
+- Suggested battery has form factor 21700
+- One battery per EPS
+- Battery is mounted in battery holder
+    - Keystone 1122 - 1122
+    - Probably additional fixation is requested
+- Selected battery - https://www.conrad.cz/p/samsung-inr21700-50e-specialni-akumulator-21700-flat-top-li-ion-akumulator-36-v-4900-mah-2114678
+    - 3.6V, 4900mAh, 17.64Wh
+    - EPS module has around 35Wh (well in limit)
+
+## Battery heating
+- https://www.ges.cz/cz/odl-20r81-GES06914579.html
+- https://www.ges.cz/cz/odl-53r1-GES06914581.html
+- https://www.gme.cz/odporovy-drat-odp-kan02-3m
+- https://www.gme.cz/odporovy-drat-odp-kon03-3m
+
+- Heating should be designed for power around 1-4W
+- With 5.4R/m and battery input source (3.7V) length of wire for 2W heating should be around 1.2m (current 0.5A)
+    - 0.5A is probably to much, values around 0.2A are better -> 1W heating
+- For regulation could be used power switch with constant current regulation
+
+# Access port module
+Connectors:
+- USB-C
+    - data connected to mission computer or flight computer
+    - power connected to EPS for battery charging
+- 2x SWD port for programing and debugging of Flight and Mission computer
+- main CAN bus connector
+- UART debug port
+
+- Realized as stack of two PCB boards
+    - Front acts only as cover for connectors
+    - Connectors are mounted on rear board
+    - Connectors are accessible via cutouts in frontz board
+    - Rear board is mounted to front via column spacers
+
 # Other parts:
 - LTC4415 - Dual ideal diode with ORing
-- MAX16171
+- MAX16171 - Ideal Diode Controller with Reverse-Current Protection
 - BQ25798 - solar battery charger with dual-input selector and MPPT, I2C, https://www.ti.com/product/BQ25798
 - BAT54W-G - Low drop shottky diode, solar blocking diode
+- BQ27421YZFT-G1A - Fuel gauge
 
-
-
-
+# Digikey orders
+https://www.digikey.cz/short/8nmn4tr3
+https://www.digikey.cz/short/d4n94tbz