Puma board for FreeEMS

[nitrousnrg]

Damn, you are right.
Microchip chips stands 25mA continuous... can't we switch back to a PIC? :P

I think the 25mA per port isn't a reliable approach neither (we use many ports so the micro can blow up, but I wouldn't consider all of them shorted). Lets put 1.6k and move on. Steady state depends on the temperature, and right now I'm not able to tell which is the cpu consumption.

[Locost_Johnh]

If using a 36 tooth wheel, and assuming a max engine RPM of 10,000 RPM, that would require a min input frequency of 360 Khz.

Maybe I'm missing something, but I think you needed a "divide by 60" in there to go from RPM to RPS. That would make the frequency only 6KHz. But since you most likely will want both edges, maybe 12KHz would be better? Still fits in the 50KHz window though.

John

[Fred]

Damn, you are right. Lets put 1.6k and move on.

Yay! :-)

I think the 25mA per port isn't a reliable approach neither (we use many ports so the micro can blow up, but I wouldn't consider all of them shorted).

I doubt that is a problem. With the above protection, the overall chip will be extremely unlikely to be over current.

I still concede that 1.6k is conservative and excessive, but I think it's a good place to be. Anything less is a risk.

[jharvey]

Maybe I'm missing something, but I think you needed a "divide by 60" in there to go from RPM to RPS. That would make the frequency only 6KHz. But since you most likely will want both edges, maybe 12KHz would be better? Still fits in the 50KHz window though.

Ah you are correct, and that would also support a min Nyquist requirement. Thanks for pointing out my math flaw.

[nitrousnrg]

The first template for a connector board:




Left and/or bottom edges should have more space for big connectors, lets see if I can rearrange some things. btw, is way too late, I shouldn't post anything being this tired.

[Fred]

Of course you should, late = funny! :-)

Is that a kicad graphic?

Fred.

[jharvey]

Yup that's KICAD graphics. I don't see the actual connectors, just the PCB to PCB connections. It's looking good.

[nitrousnrg]

Of course you should, late = funny! :-)

haha, yeah

I don't see the actual connectors, just the PCB to PCB connections

Because I intend to make different connection boards from this template.

I'd like to make a MS-like DB37 connector, so I can travel to Mendoza or Buenos Aires, and show the tuners our system in their MS cars. Fast, simple Plug&play.
I have to add to the db37 connector the constant 12v supply, extra ign outputs, cam VR, change the injectors wiring, and probably something else. Maybe this is not possible, I'm just looking at their wiring diagram, but I never had a MS in my hands. crank/cam position sensors may be a problem if the car uses the coil to sense rpm.
Well, this connector, plus a little app to create a FreeEMS config file from a MS config file would make FreeEMS easy to test and compare.

Then it would be nice to have our own universal connector (etchable @ home), and a few plug&play OEM connectors (VW, Chevrolet, Fiat). OEM connectors can be big, though. Also, there is space for an SDcard, and whatever we would want to put there. A guy asked for bluetooth too.

CAN,SPI, and UART lines are there (6-in-line pin array). The 20x2 pin array has analog and digital signals, inputs and outputs.

The analog part of the main board is being rearranged, when I complete the routing I'll update the images of the first post. Looks good so far.
Two important circuits aren't designed yet: key-driven 12v switch using *FETs, and knock sensing.

[tpsretard]

I really like this idea of a connector board

You can even do like aem and put car dependent adons if needed.

[nitrousnrg]

yeah, thats the plan!

For example, my car has two special things: Drive By Wire, and no cam sensor (though it is sequential).
In this upper board I could put the circuitry to drive the throttle and send a faked TPS signal; plus a signal to tell which phase (compression/exhaust) is occurring based on the differences of currents between the spark plugs (or something similar, I used to know how my car works).
I think this could open the possibility to drive V-tec, vanos or vvt controls through SPI or CAN.