VX Dash is an attempt at proposing a modular, cheap and entirely open-source digital instrument cluster for the Vauxhall VX220 ( also known as the Opel Speedster ). It is based on an ESP32 MCU coupled over Serial with a Nextion screen and an inexpertly designed vehicle interface PCB.
As this project is not yet in the prototype phase, the current base capabilities targeted are very similar to the original cluster :
- Full coverage of all the original Active Hi and Active Low inputs in the VX instrument clusters ( MIL light, Parking brake light, indicator lights ... )
- Fuel level display
- Engine coolant temperature display
- RPM and Speed display
Some additional functionalities are planned :
- Four 5V "ECU" sensor voltage inputs for things such as oil pressure sensors, MAP sensors, IAT/boost sensors...
- Four additional "VDO-style" analog resistive inputs, for "low impedance" voltage divider sensors, such as the ubiquitous VDO oil pressure and temperature sensors (typically 0-250Ohm)
- One "High Resistance" analog resistive input, for higher impedance sensors (typically 0-2K)
- Modular design to allow some changes between the analog resistive inputs (as in less low-R and more high-R inputs) with simple soldering
- User-personalizable sensor curves via simple code pages in Arduino IDE
- Additional free pins can be used and reassigned for variants with CAN interfaces for other vehicles
Currently the hardware design (under CERN OHL v2 Strongly Reciprocal license) features the following :
- Opto-isolated readouts of the Active Hi and Active Low cluster inputs (SFH617 optos)
- Cheap and easily flashable EPS32 dev kit C main MCU
- TVS diode protection for the 12V input, as well as a Schottky barrier for accidental over voltages
- 12V -> 5V power conversion stage built around the AP63200WU-7 converter, with a max 2A output
- 5V -> 3V3 power conversion stage built around the MP2322GQH, mimicking the power stages of the amazing Arduino Giga Wifi
- Speed and RPM pulses amplification and normalisation with an old-school C4050 non-inverting hex buffer CMOS
- Multiplexed non-critical binary inputs (Oil alarm, airbag light, ABS light, Ignition signal, Full beams light, Low coolant alarm, Brakes alarm, Alternator light, Parking Brake light, Immobilizer and Door light through a C4067 MUX
- JAE MX34036UF2 36 pin connector (unfortunately not native directly with the original harness, but adapters can be made
- Backfeed protection on the analog resistive sensor inputs
- ESD protection on the voltage sensor inputs
- Regulated 5V output to feed 5V sensors
- 3 to 4 ( in the current configuration ) direct interrupts from the binary inputs into the MCU for fast response.
- Odometer and trip distance saved in the flash memory of the MCU
- Serial communication towards a Nextion "Intelligent" 7in display (NX8048P070), with free user-customizable interface sets
- Not-yet designed, 3D printable and wrappable mechanical interface that should fit under the original instruments binnacle
Currently, this is the status of the project :
- Preliminary circuit schematic for default variant (A-sample)
- First PCB packaging
- Test of coolant temperature input readability
- Test of fuel level sensor
- Test of analog resistive sensor inputs
- Test of 5V sensor inputs
- Test of RPM pulse counter
- Test of Speed pulse counter
- Test of input muxing
- Preliminary screen HMI publication
- Arduino code first draft with only signal acquisition architecture (no odometer, no trip) and screen interface variables
- Implementation of sensor interpolation tables
- Publication of current consumption tables per functional modules
- Revision of power circuit
- Revision of fusing
- Revision of MCU input attributions
- Possible revision of MUXing strategy and "on-demand" MUXing on input change (OR CMOS needed)
- Revision of practical main connector pinout and I/O attributions (more V sensors, less R sensors, more direct MCU alarm lines ?)
- Implementation of Screen set-up pages
- Implementation of odometer and trip functions including flash saving
- PCB re-packaging
- Space-constrained enclosure design release
- Function-to-core splitting of the sensor detection loops and write-to-screen loops
- Hopefully just bug-fixing ? LOL
- Enclosure refinements
- Ultimate schematic changes
- HMI refinements
- PCB DFM iterations ( probably with PCBWay SMT services )
- ??????
- Enjoy