[simplex]

Hi,

I'm Balazs, a coder with some xp in automotive and AAA gamedev, mostly in C/C++.

I just bought a Dropbear for a Nissan VG30E D21 pickup.

I'd like to contribute to the project, and I have some questions about that.

I'd like to modify the firmware to support the staged injection for 6 cyl, and create a PR for it,
so everyone could benefit from it.

Are there any testing / development procedures that I should follow?
Like, is there some kind of tester board / etc.

How could I join the Slack dev chat? The link seems to be dead.

About the actual impl:

I assume the hw supports 6 cyl staged, as long as the injector layout is paired, and the board have 6 inj channels.
(at least, the comment in the code says so)

Is it OK to wire two injectors parallel, when injLayout == INJ_PAIRED?
Or two injectors in parallel is always safe?

As I assume it would halve the injector resistance, and I don't want to cause problems with the board.
What's the safe minimum resistance for injectors wired on a single channel?

Thanks!

[FiatDuino]

Drop Bear description on wiki says:
Pin Direction Max Current Purpose Comment
A1 Output 2A Injector 1 Injector 1 output

So 2 Amps is the limit.

You will have to measure impedance on your specific injectors and calculate what the draw will be when paired.
I did a calculation based on 12 ohms per injector and using 14 volts (the voltage that a running engine generates) and that would result in 2.3 amps per Pin. That would be too much current similar like a low impedance injector would consume.

Guidance for low impedance injectors says:
"Low-Z" ("peak and hold" or PWM-controlled) injectors that are lower impedance are used, the wiring will require series resistors on each injector to avoid damaging the board with excessive current.

You will have to check your specific conditions to determine that you can stay under the 2 amp limit.

[PSIG]

I'd like to contribute to the project, and I have some questions about that.

Awesome!

I assume the hw supports 6 cyl staged, as long as the injector layout is paired, and the board have 6 inj channels.

That should work, except you can't select paired with 12 injectors. The Staged section needs a complete review, as it doesn't work for many or most of the common combinations we see.

For example, it won't work properly for a 2 or 4-injector TBI and 6 or 8 cylinders (very common) as in a couple threads we've had this week. But it also won't work for the V6 and V8 Mustangs, Dodges, etc.

There is no provision for a V8 with 16 injectors on those, or a V6 with 2 injectors per-cylinder, which was one of the goals for cheap power adders. You could bank 3 injectors per channel for 12 injectors on 4 channels, but it won't time with 6 cylinders and ignition. And so on.

As many common staged combinations should be handled as possible, so it must be able to divide flows to #cylinders to number of staged channels. For example, selecting "TBI" should do that, but a simpler more-or-less than #cylinders should work without a TBI selection. Instead, perhaps enter number of INJ channels and it just works. It should not care how many injectors are on a channel (paired), only the number of channels and total flow per-channel. We already know the #cylinders for timing of fuel and ignition events.

Is it OK to wire two injectors parallel, when injLayout == INJ_PAIRED?
Or two injectors in parallel is always safe?

As I assume it would halve the injector resistance, and I don't want to cause problems with the board.
What's the safe minimum resistance for injectors wired on a single channel?

Paired injectors should be safe, but it depends on the specific board design, injector spec's and FETs used. Most standard 2x2 and 4x4 board designs will take 3 or 4 injectors per channel, but it is up to you to verify that! Thanks for volunteering.

[smb_29]

add a gate driver to the MCU output, then send to a MOSFET or IGBT, you have what you want

[JHolland]

How could I join the Slack dev chat? The link seems to be dead.

I think that they moved to Discord, try the link above.

[salsashocked]

How could I join the Slack dev chat? The link seems to be dead.

slope game

I think that they moved to Discord, try the link above.

I can not access this link.

[dazq]

How could I join the Slack dev chat? The link seems to be dead.

slope game

I think that they moved to Discord, try the link above.

I can not access this link.

Try this
https://discord.gg/Sa6Yy6zxK9

[Mira23]

slope game

I think that they moved to Discord, try the link above.

I can not access this link.

Try this
https://discord.gg/Sa6Yy6zxK9 word wipe

I tried and it worked, thanks