VX Dash

View this project on CADLAB.io.

What is it ?

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.

What can it do ?

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

What makes it tick ?

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

What is the timeline ?

Currently, this is the status of the project :

A-sample

• 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

B-sample

• 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

C-sample

• Hopefully just bug-fixing ? LOL
• Enclosure refinements
• Ultimate schematic changes
• HMI refinements
• PCB DFM iterations ( probably with PCBWay SMT services )
• ??????
• Enjoy