Industrial PCB Designer (ESP32-S3, 24V Power, EMI/EMC, IP65 Enclosure) – IoT Pulse Controller for Car Wash/Vacuum
Budget: $250 – $750 USD
Project Overview
We are building a V1 industrial ESP32-S3 pulse controller for self-service car wash and vacuum stations.
The device receives paid commands from a backend (MQTTS/HTTPS), and generates deterministic “coin pulses” into existing industrial controllers.
This is not a hobby prototype. It is a field-deployed V1 pilot that must remain stable for years in harsh environments.
Operating Environment
• Outdoor installation (freeze/heat cycles)
• Electrical noise: motors, pumps, inductive loads, relays/contactors
• Expected ambient: −30°C to +40°C (design margin required)
• Inside sealed IP enclosure can rise due to self-heating (design for up to ~+70°C internal with reasonable margin)
• Humidity / condensation risk (design choices should be robust)
Key Hardware Requirements
1) Power Input – 24V DC Industrial
Design must include:
• Reverse polarity protection
• Input fuse or resettable protection (PTC) + rationale
• Surge protection (TVS) sized appropriately for 24V industrial lines
• EMI mitigation strategy (input filtering / layout / return paths)
• Industrial DC/DC: 24V → 5V (and 3.3V regulation if needed), with thermal headroom
• Bulk + local ceramic decoupling discipline
• Brownout-stable design (no unstable reset loops)
2) MCU / RF
• ESP32-S3 (module or WROOM-class module acceptable if industrial-grade variant)
• Flash: 16MB target (OTA dual partitions required)
• Proper RF layout:
• antenna keep-out
• ground strategy
• ESD considerations
• Provide recommendation for antenna approach (e.g., U.FL to external 2.4GHz antenna) and exact footprint/connector selection
3) Outputs (Pulse Interface to Car Wash/Vacuum Controllers)
PCB must support three output interface options:
• PhotoMOS SSR output
• Mechanical relay output (SPDT)
• Opto-isolated open-collector output
Requirements:
• Output stage protection appropriate for inductive environments (snubbers/TVS/diodes as applicable)
• Routing/layout that prevents coupling/jitter and avoids noise injection into MCU/RF domain
• Clear separation between:
• power switching/current loops
• MCU/RF / analog sensing
4) Analog Measurement (Firmware Alignment)
• Stable ADC voltage sensing (24V line scaled to ADC range)
• Noise-robust divider + RC filtering + layout guidance
5) Programming / Production Flashing
• Must support production flashing:
• UART header OR pogo-pin footprint
• clear labeling
• Provide optional debug header (if justified)
6) Mechanical & Enclosure
• PCB must fit in IP65/IP66 enclosure (exact enclosure dimensions will be provided before layout freeze)
• Mounting holes required
• Connector orientation must be suitable for industrial wiring and serviceability
• Consider strain relief / robust connector choice (screw terminals or industrial connectors)
PCB Stackup Requirement
• 2-layer PCB required for V1 unless the engineer provides a short written justification why 4-layer is necessary (EMI/return paths/RF), including cost impact.
Firmware–Hardware Alignment (Critical)
Firmware is already developed around:
• Idempotent command execution
• Brownout + watchdog recovery
• OTA dual partition strategy
• Heartbeat + logs, device health counters
• Voltage ADC sensing
Therefore:
• Pin map and I/O table will be provided as an attachment and must be respected.
• Any proposed GPIO changes must be explicitly approved before schematic freeze.
Deliverables (Must Provide)
1. Schematic: PDF + native CAD project
2. PCB layout source files (native CAD)
3. Gerbers + drill files
4. BOM with exact manufacturer part numbers (MPNs) + alternates for supply risk
5. Pick & Place file
6. Assembly drawings + connector pinout documentation
7. Production notes (important for assembly house)
8. Short design rationale document:
• power strategy
• EMI mitigation approach
• thermal considerations
Definition of Done
• ERC/DRC clean
• Pin-map matches attached firmware table (or approved changes documented)
• All critical components available from reputable distributors (EU/CH preferred)
• Industrial protection strategy implemented and justified
• Layout follows EMI discipline (loop minimization, return paths, domain separation)
• Ready for turnkey manufacturing and assembly
Skills Required
• Industrial PCB design (24V systems)
• EMI/EMC awareness & layout discipline
• ESP32 RF layout experience
• Power integrity / protection design
• CAD tool: KiCad or Altium (state which you use)
To Apply (Screening Questions)
Please answer briefly:
1. Which CAD tool will you use, and can you deliver full source files?
2. Show 1–2 examples of industrial 24V boards you designed (or similar noisy environment designs).
3. Describe your 24V surge + reverse polarity + EMI input strategy.
4. How will you separate power/relay domain from MCU/RF domain on a 2-layer board?
5. How will you ensure reliable ADC sensing on a noisy 24V line?
6. How many schematic/layout revision cycles are included in your quote?
7. Estimated timeline for: schematic → layout → manufacturing package.
We are building a V1 industrial ESP32-S3 pulse controller for self-service car wash and vacuum stations.
The device receives paid commands from a backend (MQTTS/HTTPS), and generates deterministic “coin pulses” into existing industrial controllers.
This is not a hobby prototype. It is a field-deployed V1 pilot that must remain stable for years in harsh environments.
Operating Environment
• Outdoor installation (freeze/heat cycles)
• Electrical noise: motors, pumps, inductive loads, relays/contactors
• Expected ambient: −30°C to +40°C (design margin required)
• Inside sealed IP enclosure can rise due to self-heating (design for up to ~+70°C internal with reasonable margin)
• Humidity / condensation risk (design choices should be robust)
Key Hardware Requirements
1) Power Input – 24V DC Industrial
Design must include:
• Reverse polarity protection
• Input fuse or resettable protection (PTC) + rationale
• Surge protection (TVS) sized appropriately for 24V industrial lines
• EMI mitigation strategy (input filtering / layout / return paths)
• Industrial DC/DC: 24V → 5V (and 3.3V regulation if needed), with thermal headroom
• Bulk + local ceramic decoupling discipline
• Brownout-stable design (no unstable reset loops)
2) MCU / RF
• ESP32-S3 (module or WROOM-class module acceptable if industrial-grade variant)
• Flash: 16MB target (OTA dual partitions required)
• Proper RF layout:
• antenna keep-out
• ground strategy
• ESD considerations
• Provide recommendation for antenna approach (e.g., U.FL to external 2.4GHz antenna) and exact footprint/connector selection
3) Outputs (Pulse Interface to Car Wash/Vacuum Controllers)
PCB must support three output interface options:
• PhotoMOS SSR output
• Mechanical relay output (SPDT)
• Opto-isolated open-collector output
Requirements:
• Output stage protection appropriate for inductive environments (snubbers/TVS/diodes as applicable)
• Routing/layout that prevents coupling/jitter and avoids noise injection into MCU/RF domain
• Clear separation between:
• power switching/current loops
• MCU/RF / analog sensing
4) Analog Measurement (Firmware Alignment)
• Stable ADC voltage sensing (24V line scaled to ADC range)
• Noise-robust divider + RC filtering + layout guidance
5) Programming / Production Flashing
• Must support production flashing:
• UART header OR pogo-pin footprint
• clear labeling
• Provide optional debug header (if justified)
6) Mechanical & Enclosure
• PCB must fit in IP65/IP66 enclosure (exact enclosure dimensions will be provided before layout freeze)
• Mounting holes required
• Connector orientation must be suitable for industrial wiring and serviceability
• Consider strain relief / robust connector choice (screw terminals or industrial connectors)
PCB Stackup Requirement
• 2-layer PCB required for V1 unless the engineer provides a short written justification why 4-layer is necessary (EMI/return paths/RF), including cost impact.
Firmware–Hardware Alignment (Critical)
Firmware is already developed around:
• Idempotent command execution
• Brownout + watchdog recovery
• OTA dual partition strategy
• Heartbeat + logs, device health counters
• Voltage ADC sensing
Therefore:
• Pin map and I/O table will be provided as an attachment and must be respected.
• Any proposed GPIO changes must be explicitly approved before schematic freeze.
Deliverables (Must Provide)
1. Schematic: PDF + native CAD project
2. PCB layout source files (native CAD)
3. Gerbers + drill files
4. BOM with exact manufacturer part numbers (MPNs) + alternates for supply risk
5. Pick & Place file
6. Assembly drawings + connector pinout documentation
7. Production notes (important for assembly house)
8. Short design rationale document:
• power strategy
• EMI mitigation approach
• thermal considerations
Definition of Done
• ERC/DRC clean
• Pin-map matches attached firmware table (or approved changes documented)
• All critical components available from reputable distributors (EU/CH preferred)
• Industrial protection strategy implemented and justified
• Layout follows EMI discipline (loop minimization, return paths, domain separation)
• Ready for turnkey manufacturing and assembly
Skills Required
• Industrial PCB design (24V systems)
• EMI/EMC awareness & layout discipline
• ESP32 RF layout experience
• Power integrity / protection design
• CAD tool: KiCad or Altium (state which you use)
To Apply (Screening Questions)
Please answer briefly:
1. Which CAD tool will you use, and can you deliver full source files?
2. Show 1–2 examples of industrial 24V boards you designed (or similar noisy environment designs).
3. Describe your 24V surge + reverse polarity + EMI input strategy.
4. How will you separate power/relay domain from MCU/RF domain on a 2-layer board?
5. How will you ensure reliable ADC sensing on a noisy 24V line?
6. How many schematic/layout revision cycles are included in your quote?
7. Estimated timeline for: schematic → layout → manufacturing package.