ZombieVerter VCU V1.2

[tom91]

Instructions for the new ESP32 web-interface flashing https://openinverter.org/forum/viewtopi ... 433#p90433

[Jack Bauer]

Brilliant thanks Tom.

[wimboone]

DigiPots changed to a constant current driver that emulates a resistance range of approx 50 to 400 Ohms to ground. Inteded to drive analog fuel, temp gauges etc by emulating a resistance based sender.

So I just got the new v2 revision delivered. I was using the digipots on hardware rev1 for driving the fuel level signals on BMW E90. This was working great but doesnt work on the new v2 board. I guess this change has to do with it, but it seems the firmware does not yet include the changes? I have the latest from github master branch.

[Jack Bauer]

Thats right. The firmware does not yet support the new features. As I'm sure you are aware there are only a few of us working on this project and those that are have other commitments.

[wimboone]

Thats right. The firmware does not yet support the new features. As I'm sure you are aware there are only a few of us working on this project and those that are have other commitments.

Understood and no problem:) but I couldn't find any info on the exact hardware to implement it myself. Any schematic or is that on Patreon?

[Jack Bauer]

The schematic is in the first post of this thread. Design files will be release shortly once I confirm function on the next batch of boards due this week.

[wimboone]

Thanks, I had overlooked that.
Why is output 50 to 400 Ohm? the old digitalpot had 10k/256 steps is 39Ohm/step. and the fuelGaugeMap table being 1-19, that should be 39-741 Ohms for the fuel gauge in the E65/E90 right, or am I missing something? Otherwise I can't get the full gauge range. I have not been able to verify behaviour but will test tomorrow if I get the chance.
Firmware changes so far seems like we only need to write 1 byte extra for the channel before the value byte + hardware detection of course to not break V1 hardware.

[wimboone]

I was able to test the new digipot on hardware V2 in the car with this change to the software:

Code: Select all

void DigiPot::SetPot1Step() {
    DigIo::pot1_cs.Clear();
    spi_xfer(SPI3, 0x00); // channel 0
    spi_xfer(SPI3, Param::GetInt(Param::DigiPot1Step));
    DigIo::pot1_cs.Set();
}

void DigiPot::SetPot2Step() {
    DigIo::pot1_cs.Clear();
    spi_xfer(SPI3, 0x10); // channel 1
    spi_xfer(SPI3, Param::GetInt(Param::DigiPot2Step));
    DigIo::pot1_cs.Set();
}

After a bit of playing around with the digipot values I got this: byte value 130=100% on fuel meter in E90 dashboard. 190=75%, 222=50%, 252=25%. Notice it isn't linear, and doesn't get down to 0% which the old hardware did. I'm not very familiar with this constant current driver circuitry, anyone know what needs to be done to tune it? And just curious, why was the range of 50-400 Ohm chosen instead of the previous 0-10k?