Greetings all,
As a part of my continuing effort to make my own life more difficult, I've spent the past few months reverse engineering the (early) digital cluster and it's power supply.
You may have seen the previous links to Reddit. Now, Reddit is particularly bad about storing information (only two sites are worse, I think) so this thread will serve as a continuing documentation of my progress, while my Github will document the finished product at each stage when I'm satisfied with the result.
As mentioned on reddit, I received the finished PCBs last weekend and then spent some time assembling them. I also received a few more filament driver demo boards, which will allow me to power and test integration with all the VFD packages (there are five) before designing the actual replacement power supply.
About the filament driver demo boards:
Ultimately, this is part of my much larger effort to develop replacements for most of the electronics in the car. As they come up they'll also be documented in the same way. Currently in queue are:
As a part of my continuing effort to make my own life more difficult, I've spent the past few months reverse engineering the (early) digital cluster and it's power supply.
You may have seen the previous links to Reddit. Now, Reddit is particularly bad about storing information (only two sites are worse, I think) so this thread will serve as a continuing documentation of my progress, while my Github will document the finished product at each stage when I'm satisfied with the result.
As mentioned on reddit, I received the finished PCBs last weekend and then spent some time assembling them. I also received a few more filament driver demo boards, which will allow me to power and test integration with all the VFD packages (there are five) before designing the actual replacement power supply.
About the filament driver demo boards:
- Each one has a linear regulator and a TI push-pull driver driving a center-tapped transformer. A negative "bias" voltage is supplied at the center tap, and the result is ~2V AC heating voltage set at -18.5VDC compared to the grids and anodes. A trim pot allows the output to be precisely tuned.
- The demo boards are actually grossly oversized due to an oversight early on. I anticipated between 800mA and 1600mA filament current (depending on the package) based on supply voltage and cold resistance. However, the filaments have a very strong positive temperature coefficient. Thus, actual current is ~100mA. As such, several components aren't needed, and the push-pull transformer can (probably) be downsized to a less expensive part than the $6 Wuerth one I had selected.
- Teensy 3.5/3.6
- Level-shifting bus drivers translate the 3.3V to the 5V logic expected by the display's HV shift registers
- Parallel-in serial-out shift registers take in the 4 buttons on the front of the cluster, and the discrete inputs from the car
- Separate ADC reads in the 7 analog signals from the car:
- Supply voltage
- Fuel Level 1
- Fuel Level 2
- Oil Pressure
- Water Temperature
- Manifold Pressure
- Illumination Brightness
- (Bonus! Power supply board temperature [planned])
- Protected inputs for the 3 frequency signals from the car:
- Tachometer
- Speedometer
- Fuel Injection Pulse Width
- CANbus transciever available
- SPI EEPROM/flash available for storing misc data, including replacing the odometer with a small display.
- Supply voltages broken up in such a way that should allow powering off everything except the uC itself, which can then enter sleep mode.
- Warning light pass through, or replacement with Neopixels
Ultimately, this is part of my much larger effort to develop replacements for most of the electronics in the car. As they come up they'll also be documented in the same way. Currently in queue are:
- Time Control Unit
- Center Gauge Pod
- Fuel Level Conversion Unit (being developed as a General Module; I'll probably use two or three of them throughout the car)
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