Help regarding programming ECU.

[Anish]

Hi,
I am new to Engines as I basically took electronics engineering. I have a project to design a ECU for small engines (35cc). I am planning to use ARM-Cortex-M4 based controller @ 80Mhz. The problem is, I am not clear about stuff like volumetric efficiency etc etc. All I know is that Sensors are interfaced to the controller which modulates the pulse to the fuel injector which injects the fuel.

I now wanted to know how to program the fuel maps into the controller. I mean how do you accomplish that? I browsed the forum and found a guy used formula based approach of real time estimation of amount of fuel to be injected (with parallex controller). My concern is that, is this approach reliable? and also, I feel that at 80Mhz, the controller can outsmart the engine at real time computations. Can anyone kindly guide me?

Thanks.

[Fred]

For a single cylinder, that MCU should be a nice choice.

Don't use formulas, use tables. Give yourself a way to edit the tables live.

Does it have an FPU? If so, the math will be trivial.

Don't forget ignition.

Fred.

[Anish]

Hi fred,
thanks for your reply.
yes the mcu has a fpu. so, can i use the formula approach?
I just learned about the tables... but have no idea how to program them. I mean how to place the table in the memory such thing. I assume arrays (2d) are used to hold the value, and conditional statements are used to look for particular spot on the table. Am I correct?

[Fred]

Something like that, sort of, yes :-)

Get your hands dirty, it's the best way!

Fred.

[Anish]

Hi Fred,
Thankyou, I ll post the progressof my project. By the way, why is not this forum accessible by tapatalk?


Thanks.

[Fred]

It requires a plugin. I don't have time for that. Use a computer ;-)

[russian]

but have no idea how to program them. I mean how to place the table in the memory such thing. I assume arrays (2d) are used to hold the value, and conditional statements are used to look for particular spot on the table. Am I correct?

I am also playing with an ARM-based ECU so you might want to have a glance at my code for table lookup, it even has unit tests & interpolation:

http://sourceforge.net/p/rusefi/code/HE ... polation.c