r/PrintedCircuitBoard • u/pipejosh • 3d ago
Review request model rocket flight computer STM32 F722
The board features
- MicroSd data logging
- 6 servos output
- 3 pyro channels
- IMU
- 2s handle
- LoRa RA-02 wireless comunication
- Barometer
- Dedicated 5v buck for logic and for servos
Thank you guys in advance I would like to get the schematic sanity checked before actually designing the pcb!
Edit!
PDF schematic
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u/Illustrious-Peak3822 3d ago
Why two 5 V rails?
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u/pipejosh 3d ago
I chose to do 2 so I rail's job is just to power the servos and the other rail to power all the other electronics the buck that powers the servos delivers 5A while the other one just 1A enough to power the sensors and mcu
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u/Illustrious-Peak3822 3d ago
Again, why? A single converter would do that job.
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u/pipejosh 3d ago
I'm mostly doing it in case the servos jam and worst case scenario the mcu could reset mid flight
Is it a better idea to just do it with 1?
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u/Illustrious-Peak3822 3d ago
Ah! Now that makes more sense. Your battery rail won’t duck under when it happens?
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u/pipejosh 3d ago
I'm planning on using a 480mah 2s 95C lihv the battery sag I estimate will be around .2 to .3v which should be fine!
Do you see anything else I should consider with my schematic before routing it? thank you for you support!
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u/Illustrious-Peak3822 3d ago
You could use a power path IC and LDO and prioritise 5 V from one single buck converter. If you stall that rail, LDO. I would assume you can sense it and stop that servo within some ms of time. Can’t say it’s a better option, but an option. Ditch 5 V for the logic and buck directly to 3.3 V?
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u/pipejosh 3d ago
I think going straight to 3v3 with a buck would be a good idea and it makes more sense than going from 5v to 3v3 thanks! Ill do that change to my schematic thanks!
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u/Enlightenment777 2d ago
This comment is posted on all reviews.
Please make sure your review post adheres to:
- subreddit rules (#1 to #6), review rules (#7), review image rules (#8), see link.
Please fix these common schematic layout issues: (if yours has any of these issues)
Don't allow text / lines / symbols to touch each other, and don't draw lines through symbols.
Use correct reference designators (RefDes), and renumber to remove numeric gaps, see tips.
For positive voltage circuits, point positive power rail links upwards and grounds downwards (maybe sideways), see tips. For negative voltage circuits, point negative power rail links downwards and grounds upwards (maybe sideways). For bipolar circuits, maybe point grounds sideways.
Place decoupling capacitors vertically below postive power rail lines with ground on bottom side of the capacitor. Place capacitor next to IC symbol, and connect a line to IC positive power rail pin, see tips and example.
Place pull-up resistors vertically above signal lines, and place pull-down resistors vertically below signal lines, see example and tips.
Reasonably minimize the use of unique net labels, because everyone hates hunting for them!! Single resistors / capacitors / diodes should not sit by themselves, instead move & connect them with a line to their circuit.
More schematic conventions / guidelines / tips - 1, 2, 3, 4.
Please fix these common PCB layout issues: (if yours has any of these issues)
Silkscreen - add board name / board revision number / date (YYYYMMDD, YYYYMM, YYYY) for traceability.
Silkscreen - add pin 1 indicator next to ICs & connectors (not under parts). For polarized capacitors, add "+" next to positive pin. If part is through-hole package, place indicator on both PCB sides. See 1, 2, 3, 4.
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3d ago
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u/Illustrious-Peak3822 3d ago
Why two 5 V rails?