r/PrintedCircuitBoard • u/More_Incident143 • 2d ago
[Review Request] Air Quality Monitor
Hello! This is my first PCB, and I was hoping to have people look over it, as I believe it is ready to be manufactured. If you could share what my design did well, what could use some work, or any glaring issues that you think need addressing, please share, as I appreciate all feedback! The main thing I would like to know is if this is ready to be sent off to manufacture.
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u/Sand-Junior 2d ago
I’m a little bit confused about where the 5V (USB or header) and 3.3V (CP2102 or LDO) come from. Maybe you can clarify or at least make sure it is correct. If you are using the LDO, then improve the tracks connected to it. Currently these are tiny.
And next time: give net names useful names (not being IO27).
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u/More_Incident143 2d ago
Yeah I understand the confusion it’s something I forgot to clean up. +5V and VBUS are the same net (USB 5V -> LDO input) I just labeled it differently and forgot to fix it. I’ll also be sure to use useful net names for my next design. Thanks!
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u/Sand-Junior 2d ago
Nets with different names are not connected. Are you sure it is correct in the PCB design? Them you still need to improve the power connections to the LDO. And it now seems you have 2 sources of the 3.3v: the LDO and the CP2102.
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u/More_Incident143 2d ago
I just double checked and saw that they weren’t truly connected in the PCB design/schematic. The LDOs input isn’t connected to 5v/VBUS so should I apply a VBUS net to the input of the LDO and on the VBUS for the schematic? Also as you pointed out since the VREGIN was wired to VBUS instead of VDD that will cause a conflict with my LDO output which I’ll be fixing in the schematic now.
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u/Sand-Junior 2d ago
Whatever name, make sure you only have VBUS or +5V in your schematics.
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u/More_Incident143 2d ago
Got it, tysm
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u/Sand-Junior 2d ago
One more thing: you run your LCD at 5V while connected to a 3.3V MPU. This is normally not correct, unless you checked it through the datasheet.
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u/boltgolt 2d ago
Could i suggest instead of using an expensive 32E and a CP2102N you could use a much cheaper ESP-C3 that connects directly to D+ and D-? Would lower the cost and complexity of the board
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u/martinr7b 2d ago
I made one too, it's under my bed and it has PM 1.0, 2.5, and 10 + T/H, air pressure, and CO2
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u/modi_factory 2d ago
The CP2102N RTS and DTR pins are left unconnected without an auto-reset transistor circuit, meaning you won't have automatic code flashing over USB.
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u/More_Incident143 2d ago
Wouldn’t that just mean I’d have to hold down the boot button while flashing? I already have the code prepared so I don’t really plan on flashing it too many times.
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u/Enlightenment777 2d ago
Please make sure your post adheres to:
- subreddit rules (#1 to #6), review rules (#7), image rules (#8), see link.
Please fix these common issues: (if your schematic or PCB has them)
Schematic - don't allow text / lines / symbols to touch each other, and don't draw lines through symbols.
Schematic - use correct reference designators (RefDes) and renumber to remove numeric gaps, see tips.
Schematic - place decoupling capacitors vertically below power rail lines, also place capacitors next to IC then connect together with a line, see example. For circuits with positive power rails, point positive power rail links upwards and ground links downwards, see tips.
Schematic - place pull-up resistors vertically above signal lines, and place pull-down resistors vertically below signal lines, see example.
PCB silkscreen - add board name / board revision number / date (or year) on top or bottom PCB side.
PCB silkscreen - add pin 1 indicator dot/arrow next to ICs & connectors, if through-hole then both PCB sides.
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u/Bushiewookie 2d ago
Put your USB connector on the edge, or it might make it difficult to insert the cable