Проектирование платы
Project Name: Universal IoT Controller (OpenCPU ML307R)
Version: 2.0 (Multi-purpose: Car Wash / Access Control)
Core Module: OneMO (China Mobile) ML307R
1. Project Overview
Design a compact PCB for telemetry and control based on the ML307R LTE Cat.1 module.
Architecture: OpenCPU (No external MCU). All logic is implemented within the ML307R processor.
Application: The board will be used in two modes:
Car Wash/Vending: Counting pulses from Coin/Bill acceptors.
Access Control: Reading RFID cards via Wiegand interface.
2. Power Supply System (Critical Requirement)
The device operates in harsh environments with voltage drops.
Input Voltage: 9V ... 30V DC (Nominal 12V/24V).
Main Regulator: Synchronous Buck Converter (DC-DC).
Target Chip: MP1584EN or TPS54331. DO NOT use LDOs.
Output: Strictly 3.8V (VBAT).
Current Capability: Min 2.5A peak.
Stability: Required Tantalum Capacitor (min 470uF, Case D/E) or Polymer Low-ESR cap (1000uF) on the VBAT line to prevent reboots during LTE transmission.
Protection: Reverse polarity protection (Schottky Diode), PTC Fuse, TVS diode on input.
3. Inputs & Interfaces
A. Payment Inputs (Pulse/Switch)
Qty: 2 Independent Channels (Input 1, Input 2).
Type: Optoisolated (PC817 / EL357).
Connector: Screw Terminal.
Logic: Detect 12V/24V pulses from Coin/Bill acceptors.
B. Access Control Input (Wiegand Protocol)
Qty: 1 Interface (Data 0, Data 1).
Connector: 4-pin Terminal (12V Out, GND, D0, D1).
Level Shifting (CRITICAL):
Wiegand readers output 5V logic.
ML307R GPIOs accept 1.8V max.
Requirement: Implement a Hardware Level Shifter (MOSFET-based or logic IC) to safely connect 5V D0/D1 lines to 1.8V modem GPIOs.
Power Output: 12V passthrough to power the reader (protected by fuse).
C. Communication
UART: 2 ports (JST XH 4-pin) for external Display/Printer.
Must include Level Shifters (1.8V <-> 3.3V/5V).
USB: Type-C (for Firmware Download/Debug).
SIM: Nano-SIM slot with ESD protection.
4. Outputs (Relay Control)
Qty: 2 Channels.
Type: Dry Contact (COM/NO).
Driver: MOSFET (2N7002) driving a small Relay or PhotoMOS (Solid State).
Load: Capable of switching 12V/24V solenoids (with Flyback diode protection).
5. PCB Layout & Form Factor
Reference: See attached photos of the original green board.
Connectors:
Power & Inputs (Pulse/Wiegand) on the bottom edge (Screw Terminals).
Relay Outputs on the bottom edge (Screw Terminals).
UARTs on the side (JST).
Indication (LEDs): Power (3.8V), Net Status, Relay 1 Active, Relay 2 Active.
Mounting: 4 mounting holes (M3).
6. Deliverables
Schematic Diagram (PDF + Source).
PCB Layout (Gerber Files + Source).
BOM (Bill of Materials) with LCSC part numbers.
Pick & Place file (CPL) for assembly.
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20 days1500 USD
408 12 1 20 days1500 USDHello, my name is Stepan. I have solid experience in PCB design. I can help you realize your project with a competent component layout, a well-designed electrical schematic, and a high-quality PCB, fully aligned with your requirements.
I work with a strong focus on quality and safety. My goal is to deliver a product without mistakes, since errors usually lead to additional PCB orders and extra costs for the client.
Your project is very interesting and requires careful and thoughtful design, which is exactly what I can offer.
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30 days300 USD
274 7 2 30 days300 USDReady to complete your project. For discussing details, write in the personal account.
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15 days300 USD
300 1 1 15 days300 USDGood day! I have reviewed your technical specification, I can complete it. Write to me and we will discuss the details and get to work.
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2 days100 USD
2259 5 1 2 days100 USDHello! I have reviewed your assignment and believe that I can successfully complete it. I would be happy to collaborate, please write to me personally for further details.
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30 days250 USD
1098 9 0 30 days250 USDI can do it without any special problems, I have experience, I will do it in EasyEda.
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21 days200 USD
1832 12 1 21 days200 USDHello, there are some developments, the compilation of which will provide a normal reliable solution. All the outlined issues are already taken into account in these pieces of the scheme, there are no problems at all with level conversion.
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