Custom Teensy Automotive Diagnostics Board
Budget: €30 – €250 EUR
1. Project Overview
The objective of this project is to design a professional, industrial-grade custom carrier board (PCB) for a Teensy 4.1 microcontroller. The board will be used in an automotive test-bench environment to sniff data from a VAG DQ200 DSG gearbox, read high-speed engine RPM from a 3-wire Hall effect sensor, monitor real-time supply voltage via an I2C sensor, and transmit all telemetry data over an RS485 bus to an external display.
CRITICAL NOTE FOR THE FREELANCER: This project covers HARDWARE DESIGN ONLY (Schematic Capture, PCB Layout, and Manufacturing Files generation). Firmware and software development are completely excluded from this scope and will be handled internally by the client.
2. Hardware Pin Mapping & Software Particulars
To maintain absolute compatibility with our internal firmware development, all hardware interfaces must be routed strictly to the following native Teensy 4.1 pins:
• RS485 Communication (Serial1):
o Digital Pin 0 (RX1) $\rightarrow$ Connected to the RO (Receiver Output) pin of the RS485 transceiver.
o Digital Pin 1 (TX1) $\rightarrow$ Connected to the DI (Driver Input) pin of the RS485 transceiver.
o Digital Pin 5 $\rightarrow$ Connected to the tied DE/RE (Driver Enable / Receiver Enable) pins for software-managed hardware direction switching.
• CAN 1 Interface (Classic):
o Digital Pin 44 (CTX1) and Digital Pin 45 (CRX1) $\rightarrow$ Routed to the first CAN transceiver.
• CAN 2 Interface (Classic):
o Digital Pin 3 (CTX2) and Digital Pin 2 (CRX2) $\rightarrow$ Routed to the second CAN transceiver.
• CAN 3 Interface (High-Speed CAN-FD):
o Digital Pin 23 (CTX3) and Digital Pin 22 (CRX3) $\rightarrow$ Routed to the third CAN transceiver (designated for high-speed CAN-FD data).
• Senzor Hall Input (RPM Reading):
o Digital Pin 4 $\rightarrow$ Connected to the isolated collector output of the optocoupler. When a magnet passes the sensor, the optocoupler must pull Pin 4 down to the internal Teensy GND, generating a hardware-friendly FALLING edge trigger.
• Voltage Monitor Interface (I2C Bus):
o Digital Pin 18 (SDA) and Digital Pin 19 (SCL) $\rightarrow$ Routed to the digital power monitor IC.
• Ethernet Interface:
o The 6 internal Ethernet pads located on the Teensy 4.1 PCB $\rightarrow$ Routed directly to the board-mounted RJ45 connector.
3. Detailed Hardware Block Requirements
3.1 Power Supply Stage (Automotive Grade Step-Down)
• Input Voltage: 12V–14.8V DC (Vehicle battery / Bench power supply).
• Reverse Polarity Protection: A P-MOSFET circuit configuration (Reference part: AOSS21311C or equivalent) must be used to provide robust reverse polarity safety with zero forward voltage drop.
• Transient Suppression: A high-power TVS Diode (Reference part: SMAJ36) must be placed immediately at the 12V input rail to clamp inductive spikes, cranking noise, and vehicle load dumps.
• Primary Regulator: A high-efficiency DC-DC Step-Down Buck Converter delivering a stable 5V DC output to the Teensy VIN pin (Reference design: XL1509-5.0 or similar integrated switcher layout).
• Auxiliary Power Rail: An on-board dedicated 3.3V LDO regulator to power auxiliary ICs (all transceivers and sensors), completely offloading the Teensy 4.1 internal regulator to prevent thermal stress.
3.2 Triple CAN Bus Interface
• Transceivers: 3x Independent CAN interfaces using MCP2562FD-E/SN (or compatible high-speed TJA1044GT) transceivers, ensuring all 3 physical lines fully support CAN-FD high-speed protocols (up to 5-8 Mbps).
• Voltage Logic Level Matching: Transceivers must use the 5V rail for VDD (bus power) and the Teensy 3.3V rail for VIO to ensure native logic-level compatibility with the MCU processing pins.
• Termination Resistors: Each of the 3 CAN channels must feature an on-board 120-Ohm termination resistor connected through a physical 2-pin header/jumper for manual circuit activation.
• ESD Protection: Dedicated low-capacitance ESD protection diode arrays (Reference part: PESD1CAN) must be placed on all physical CAN High and CAN Low external signal lines.
3.3 RS485 Communication Interface
• Transceiver: 1x RS485 Transceiver operating natively at 3.3V logic (Reference part: MAX3485 or SP3485).
• Direction Control: DE and RE pins must be tied together and routed to Digital Pin 5 for firmware-driven stream management.
3.4 Optically Isolated RPM Sensor Input
• Interface: A 3-pin terminal block for a standard 5V Hall Effect speed sensor (VCC 5V, GND, Signal).
• Galvanic Isolation: The incoming pulse signal must be isolated from the Teensy via a high-speed PC817 optocoupler. This prevents ground loops between the engine block and the test bench from corrupting the MCU rails. The isolated output transistor must switch Teensy Digital Pin 4 to internal GND.
3.5 Digital I2C Voltage Monitoring Stage
• Sensor IC: 1x INA219 (or INA226) digital power/voltage monitor IC mapped to I2C pins 18 and 19.
• Bus Hardware: Include 2x 4.7k-Ohm pull-up resistors on the SDA and SCL lines tied directly to the 3.3V auxiliary power rail.
• Measurement Target: The sensor’s $V_{BUS}$ sensing pin must tap the main 12V automotive input line after the TVS diode and MOSFET protection stage to read true system voltage sags during motor operations.
3.6 Dedicated USB Protection Stage
• Data Line ESD Protection: A dedicated, ultra-low capacitance ESD protection diode array (Reference part: USBLC6-2SC6 or PRTR5V0U2X) must be placed inline on the USB D+ and D- high-speed data lines between the external USB connector and the Teensy 4.1 USB pads.
• Power Isolation Jumper: The VBUS (5V USB) trace from the external USB connector must pass through a physical, manually switchable 2-pin header/jumper before connecting to any internal rail. This guarantees that the diagnostic laptop's USB power can be completely isolated from the on-board 12V-to-5V Buck converter, preventing backfeeding currents.
• Noise Filtering: Include a ferrite bead on the USB shield/GND path to isolate high-frequency test-bench noise.
3.7 Ethernet Interface
• Differential pairs must be routed from the Teensy 4.1 internal 6-pin Ethernet pad layout directly to a board-mounted RJ45 MagJack connector featuring integrated isolation transformers (Reference part: HR911105A).
4. Deliverables & Production Files Requirements
The freelancer must supply a complete, turnkey manufacturing package optimized for direct submission to automated PCB fabrication and SMT component assembly houses (e.g., JLCPCB, PCBWay). The required outputs are:
1. Gerber Files: Extended Gerber format (RS-274X or Gerber X2) including all copper layers, solder masks, silkscreens, and drill-guide board outlines.
2. NC Drill Files: Excellon format specifying precise coordinates for all through-holes and vias.
3. Bill of Materials (BOM): A structured spreadsheet (.csv or .xlsx) containing Component Designators, Quantities, Footprint packages, Descriptions, and explicit LCSC, DigiKey, or Mouser Part Numbers to guarantee exact matching during automated picking.
4. Component Placement List (CPL / Centroid File): A precise coordinate data file (.csv or .txt) mapping X/Y positions, exact rotation angles, and layer placement (Top/Bottom) for all SMD devices to calibrate automated SMT assembly robots.
5. Stencil Files: Solder paste stencil mask layers (GTP for Top / GBP for Bottom).
6. Assembly Drawings: High-resolution PDF visual layouts clearly identifying component orientations, polarization markers (Pin 1 dots, diode bands, capacitor polarities).
7. Native Design Files: The complete, uncompiled original project structure and schematics from the chosen EDA platform (KiCad, EasyEDA, or Altium Designer) for future design iterations.
The objective of this project is to design a professional, industrial-grade custom carrier board (PCB) for a Teensy 4.1 microcontroller. The board will be used in an automotive test-bench environment to sniff data from a VAG DQ200 DSG gearbox, read high-speed engine RPM from a 3-wire Hall effect sensor, monitor real-time supply voltage via an I2C sensor, and transmit all telemetry data over an RS485 bus to an external display.
CRITICAL NOTE FOR THE FREELANCER: This project covers HARDWARE DESIGN ONLY (Schematic Capture, PCB Layout, and Manufacturing Files generation). Firmware and software development are completely excluded from this scope and will be handled internally by the client.
2. Hardware Pin Mapping & Software Particulars
To maintain absolute compatibility with our internal firmware development, all hardware interfaces must be routed strictly to the following native Teensy 4.1 pins:
• RS485 Communication (Serial1):
o Digital Pin 0 (RX1) $\rightarrow$ Connected to the RO (Receiver Output) pin of the RS485 transceiver.
o Digital Pin 1 (TX1) $\rightarrow$ Connected to the DI (Driver Input) pin of the RS485 transceiver.
o Digital Pin 5 $\rightarrow$ Connected to the tied DE/RE (Driver Enable / Receiver Enable) pins for software-managed hardware direction switching.
• CAN 1 Interface (Classic):
o Digital Pin 44 (CTX1) and Digital Pin 45 (CRX1) $\rightarrow$ Routed to the first CAN transceiver.
• CAN 2 Interface (Classic):
o Digital Pin 3 (CTX2) and Digital Pin 2 (CRX2) $\rightarrow$ Routed to the second CAN transceiver.
• CAN 3 Interface (High-Speed CAN-FD):
o Digital Pin 23 (CTX3) and Digital Pin 22 (CRX3) $\rightarrow$ Routed to the third CAN transceiver (designated for high-speed CAN-FD data).
• Senzor Hall Input (RPM Reading):
o Digital Pin 4 $\rightarrow$ Connected to the isolated collector output of the optocoupler. When a magnet passes the sensor, the optocoupler must pull Pin 4 down to the internal Teensy GND, generating a hardware-friendly FALLING edge trigger.
• Voltage Monitor Interface (I2C Bus):
o Digital Pin 18 (SDA) and Digital Pin 19 (SCL) $\rightarrow$ Routed to the digital power monitor IC.
• Ethernet Interface:
o The 6 internal Ethernet pads located on the Teensy 4.1 PCB $\rightarrow$ Routed directly to the board-mounted RJ45 connector.
3. Detailed Hardware Block Requirements
3.1 Power Supply Stage (Automotive Grade Step-Down)
• Input Voltage: 12V–14.8V DC (Vehicle battery / Bench power supply).
• Reverse Polarity Protection: A P-MOSFET circuit configuration (Reference part: AOSS21311C or equivalent) must be used to provide robust reverse polarity safety with zero forward voltage drop.
• Transient Suppression: A high-power TVS Diode (Reference part: SMAJ36) must be placed immediately at the 12V input rail to clamp inductive spikes, cranking noise, and vehicle load dumps.
• Primary Regulator: A high-efficiency DC-DC Step-Down Buck Converter delivering a stable 5V DC output to the Teensy VIN pin (Reference design: XL1509-5.0 or similar integrated switcher layout).
• Auxiliary Power Rail: An on-board dedicated 3.3V LDO regulator to power auxiliary ICs (all transceivers and sensors), completely offloading the Teensy 4.1 internal regulator to prevent thermal stress.
3.2 Triple CAN Bus Interface
• Transceivers: 3x Independent CAN interfaces using MCP2562FD-E/SN (or compatible high-speed TJA1044GT) transceivers, ensuring all 3 physical lines fully support CAN-FD high-speed protocols (up to 5-8 Mbps).
• Voltage Logic Level Matching: Transceivers must use the 5V rail for VDD (bus power) and the Teensy 3.3V rail for VIO to ensure native logic-level compatibility with the MCU processing pins.
• Termination Resistors: Each of the 3 CAN channels must feature an on-board 120-Ohm termination resistor connected through a physical 2-pin header/jumper for manual circuit activation.
• ESD Protection: Dedicated low-capacitance ESD protection diode arrays (Reference part: PESD1CAN) must be placed on all physical CAN High and CAN Low external signal lines.
3.3 RS485 Communication Interface
• Transceiver: 1x RS485 Transceiver operating natively at 3.3V logic (Reference part: MAX3485 or SP3485).
• Direction Control: DE and RE pins must be tied together and routed to Digital Pin 5 for firmware-driven stream management.
3.4 Optically Isolated RPM Sensor Input
• Interface: A 3-pin terminal block for a standard 5V Hall Effect speed sensor (VCC 5V, GND, Signal).
• Galvanic Isolation: The incoming pulse signal must be isolated from the Teensy via a high-speed PC817 optocoupler. This prevents ground loops between the engine block and the test bench from corrupting the MCU rails. The isolated output transistor must switch Teensy Digital Pin 4 to internal GND.
3.5 Digital I2C Voltage Monitoring Stage
• Sensor IC: 1x INA219 (or INA226) digital power/voltage monitor IC mapped to I2C pins 18 and 19.
• Bus Hardware: Include 2x 4.7k-Ohm pull-up resistors on the SDA and SCL lines tied directly to the 3.3V auxiliary power rail.
• Measurement Target: The sensor’s $V_{BUS}$ sensing pin must tap the main 12V automotive input line after the TVS diode and MOSFET protection stage to read true system voltage sags during motor operations.
3.6 Dedicated USB Protection Stage
• Data Line ESD Protection: A dedicated, ultra-low capacitance ESD protection diode array (Reference part: USBLC6-2SC6 or PRTR5V0U2X) must be placed inline on the USB D+ and D- high-speed data lines between the external USB connector and the Teensy 4.1 USB pads.
• Power Isolation Jumper: The VBUS (5V USB) trace from the external USB connector must pass through a physical, manually switchable 2-pin header/jumper before connecting to any internal rail. This guarantees that the diagnostic laptop's USB power can be completely isolated from the on-board 12V-to-5V Buck converter, preventing backfeeding currents.
• Noise Filtering: Include a ferrite bead on the USB shield/GND path to isolate high-frequency test-bench noise.
3.7 Ethernet Interface
• Differential pairs must be routed from the Teensy 4.1 internal 6-pin Ethernet pad layout directly to a board-mounted RJ45 MagJack connector featuring integrated isolation transformers (Reference part: HR911105A).
4. Deliverables & Production Files Requirements
The freelancer must supply a complete, turnkey manufacturing package optimized for direct submission to automated PCB fabrication and SMT component assembly houses (e.g., JLCPCB, PCBWay). The required outputs are:
1. Gerber Files: Extended Gerber format (RS-274X or Gerber X2) including all copper layers, solder masks, silkscreens, and drill-guide board outlines.
2. NC Drill Files: Excellon format specifying precise coordinates for all through-holes and vias.
3. Bill of Materials (BOM): A structured spreadsheet (.csv or .xlsx) containing Component Designators, Quantities, Footprint packages, Descriptions, and explicit LCSC, DigiKey, or Mouser Part Numbers to guarantee exact matching during automated picking.
4. Component Placement List (CPL / Centroid File): A precise coordinate data file (.csv or .txt) mapping X/Y positions, exact rotation angles, and layer placement (Top/Bottom) for all SMD devices to calibrate automated SMT assembly robots.
5. Stencil Files: Solder paste stencil mask layers (GTP for Top / GBP for Bottom).
6. Assembly Drawings: High-resolution PDF visual layouts clearly identifying component orientations, polarization markers (Pin 1 dots, diode bands, capacitor polarities).
7. Native Design Files: The complete, uncompiled original project structure and schematics from the chosen EDA platform (KiCad, EasyEDA, or Altium Designer) for future design iterations.