5V Injector Signal

[cfordyce05]

I have a special injector that requires that it be driven from the manufacturer's driver circuit. The driver circuit requires a 5V logic level TTL signal to turn the injector on. Is there someplace in the MicroSquirt V2.0 injector driver circuit that I can tap into to get the 5V signal that is driving the injector MOSFET (I guess I'm assuming its a logic level input)? Maybe just solder a lead onto the INPUT on U6 VND5N07?

Would it be easier to convert the 12V injector pulse back to 5V? If so, what type of components/circuit would I use?

Is there an alternate output that can be used like the LEDs on the MegaSquirt?

I can use whatever firmware will support the feature if its available!

Thanks,

Casey

[cfordyce05]

I think I may try a resistor from the 12V signal and a zener diode to bring it down to 5.1V. I'll report back how that works.

[dontz125]

You're going to want a buffer circuit of some sort; a direct connection from the processor to the Great Outdoors (including your direct lead to the VND5N07) is a quick way to fry your processor.

The problem with converting the injector signal from +5v to +12v is that the uS injector is a grounding signal, not a positive pulse.

Can you provide a wiring schematic for this device - I assume it's like a 4-pin logic COP?

[abecedarian]

You might be able to use a PNP transistor: MS injector output to the base, 5v to the collector, your injector to the emitter. When the base goes to ground, the transistor will conduct 5v across the collector and emitter. Likely a P-channel mosfet might be better though, and wired similarly.

[cfordyce05]

That is actually the direction I'm headed in. I have the mosfet wired up but I haven't run it yet.