How fast does a PC have to be

[Howard]

In order to adequately emulate a good ECU?

Let's say I had a crate engine but wasn't satisfied with any of the available ECU options. Could I hook up a laptop with some sort of custom transceiver (for the proper voltage I/O and wiring) and control it using PC software?

 

[Yuriman]

I believe people have made custom ECUs before with an arduino, though modern cars probably have more going on, higher polling rates, etc. and likely require some extra processing power.

 

[KentState]

Any modern PC can handle the duties, the problem is the OS and software. You would not want processing to be waiting on the OS to complete a back ground task of some sort. A car will have a dedicated sub-system with built in redundancy. A system "stutter" is not something you want to see when knock is being detected

 

[nedfunnell]

Haltech ECU won't do it for you?

 

[Pulsar]

Windows is not a realtime operating system. It doesn't matter how fast the computer is practically speaking.

 

[LevelSea]

Any modern PC can handle the duties, the problem is the OS and software. You would not want processing to be waiting on the OS to complete a back ground task of some sort. A car will have a dedicated sub-system with built in redundancy. A system "stutter" is not something you want to see when knock is being detected

Do PC processors have PWMs, DACs, ADCs, programmable GPIOs, etc? Even if you had a RTOS, you'd need to have those analog interfaces to control injectors, read throttle position and such.

 

[KentState]

Do PC processors have PWMs, DACs, ADCs, programmable GPIOs, etc? Even if you had a RTOS, you'd need to have those analog interfaces to control injectors, read throttle position and such.

They do.

 

[LevelSea]

They do.

:thumbsup: Learn something new everyday.

 

[KentState]

:thumbsup: Learn something new everyday.

Still would be a very round about way to do something where a purpose built ECU is much more integrated and simplified.

 

[JCH13]

A PLC would likely be the way to go.

Why aren't the available ECU options satisfactory?

 

[Midwayman]

The amount of processing power is trivial by today's PC standards. The real issue is interface and OS. You'd probably get more mileage out of a dedicated ECU with PC software. I had a link ECU over a decade ago that did that.

 

[Howard]

A PLC would likely be the way to go.

Why aren't the available ECU options satisfactory?

I'm sure they are. The question is academic.

Don't PLCs have a scanning rate of only up to 10 Hz or so? I expect that to be too slow for what an engine needs.

 

[JCH13]

I'm sure they are. The question is academic.

Don't PLCs have a scanning rate of only up to 10 Hz or so? I expect that to be too slow for what an engine needs.

Rodger that.

Here's a random article I found that references 'typical' scan times of PLCs: http://www.electrocam.com/pdf/tech/SCANTIME.PDF

It notes 3-100ms, or 333-100hz. Not amazingly fast, but I imagine that faster PLCs exist. As long as the resolution of the timing in the PLC is good enough 333hz should be a plenty-fast scan rate (I would think).

Edit: A micro-controller, like an arduino, would also work. This is essentially what a Megasquirt is: a microcontroller with code and accessory hardware to run an engine.

I would be hesitant to use a PC to control an ECU, PLCs and microcontrollers are used for this type of application IRL for reasons beyond computing power, of which they have plenty.