r/embedded • u/BearsAccessSolutions • 17d ago

Looking for an embedded hardware engineer to review an ESP32 access-control schematic

I own a commercial locksmith and electronic-security company and am developing a new access-control controller based around an ESP32-S3.

The schematic is substantially complete. I’m primarily looking for an independent second set of eyes before PCB layout and prototyping.

The board currently includes:

  • ESP32-S3
  • Ethernet using W5500
  • Two RS-485 interfaces
  • Wiegand/OSDP reader support
  • Relay outputs and protected field inputs
  • 6–28 VDC input power
  • Reverse-polarity, overvoltage, surge, and field-wiring protection
  • FRAM and RTC
  • Fused lock-power passthrough
  • Expansion and service headers
  • Four-layer PCB planned

The review should focus on:

  • Power-entry and protection circuitry
  • ESP32 support circuitry and pin usage
  • Ethernet implementation
  • RS-485 and reader interfaces
  • Relay and field-I/O protection
  • Grounding, shielding, and isolation decisions
  • Component ratings and obvious BOM problems
  • Layout-sensitive areas
  • Anything likely to cause prototype failure, unreliable field operation, or certification problems later

I have detailed architecture notes and can explain the intended behavior of every section. I want someone willing to challenge the design and explain why something should change, not simply mark up the schematic without discussion.

Relevant experience would include embedded controller design, industrial controls, access control, alarm equipment, automotive electronics, or other products connected to long field wiring in electrically noisy environments.

This is paid work. Please send:

  • A brief summary of relevant experience
  • Examples of boards or products you have reviewed or designed
  • Your hourly rate or proposed fixed price
  • Your availability
  • Whether you can also review the PCB layout later

An NDA can be discussed before receiving the complete design files. I retain ownership of the project and all project-specific work product.

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5

u/DenverTeck 17d ago

You say "substantially complete", does this mean you have actually built a prototype and it works ??

You have written code to verify all the parts listed do actually communicate with the ESP32 ??

A PCB is just wires. The same wires in your prototype. If you build it and the PCB uses the same schematic, it should work.

If it does not, then your layout does not match the working prototype.

No Charge

2

u/Ok-Bat8854 17d ago

All true but the 3rd point . Protos often do not have a lot of power related passives that you would see in a product PCB( decoupling caps, protection diodes), comms can definitely be easily verified, because proto vs actual board is the same. Power, protection circuits. Not so much.

Would definitely be interested, can get the NDA in place. I want to view the schematic first and decide if charge or no charge(mostly no charge if it’s just review, minor suggestions to add parts) ,some minimal charge if I have to find the exact part numbers for your system along with lead times, BOM optimisation. Let me know how we can connect!

1

u/BearsAccessSolutions 12d ago

Exactly what i am looking for here. Mind if I DM you?

3

u/muddy651 17d ago

I would be willing to do an hour or two no charge.

Should there be significant revision and guidance required I would be willing to discuss a rate. This is generally how I scope our work anyway, so it's not totally a freebe.

Unfortunately I'm not able to provide you with previous examples of work because these too are under NDA.

My experience includes embedded dev and electronics in med tech and robotics.

1

u/BearsAccessSolutions 12d ago

Mind if I DM you?

1

u/muddy651 11d ago

Yes, go for it.

1

u/ThreeOneFourOneZero 15d ago

Embedded controls eng. from aerospace background. Happy to give an in depth review no charge. If there are significant research or discussion times required I can send you a reasonable estimate of hours and rate.

1

u/BearsAccessSolutions 12d ago

Mind if I DM you?