DIYEFI.org Forum

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.

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.

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?

Something like that, sort of, yes :-)

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

Fred.

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


Thanks.

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

Anish wrote: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