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Whats a super fast Analog I/O Processor?

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Gumby83:
Hello friends, i am looking for some advice. I am 100% a newbie, but i just recently got interested in a specific project i have. so i have only been learning about electronics for 4-5 days. I had an electrical engineer helping with the basics, but it really wasnt his field. So i come to you fine folk with a few questions.   
 
First i have to discribe what i am trying to do, this is an automotive application so 12vdc, i am trying to take 8 injector signals for a set of high impedance fuel injectors (saturated circut style) and duplicate them to two sets of 8.   
 
The Engine control computer has +12v running to one side of all the injectors at all times, then fires them individually using a ground signal, that ground signal will be shorter or longer for more or less fuel depending on engine loads and fuel demands.   
 
The injector drivers in the engine control computer cannot handle 16 injectors, so i am going to try to build a logic board that has 16 injector drivers (transistors AFAIK) that will duplicate the original injector signal to two sets of 8 with its own power/ground supply. 
 
Lets call them "injector set A" and "injector set B". Idea is to have a 0-5v sensor determine when injector set A is in operation (0-2.5v) and when Injector set B is in operation (2.5-5v), however i need to have a crossover period of around 100ms (where both injectors are working together before shutting down the other injector set)   
 
Ideally with the lowest possible latancy. I would also like the ability to adjust when the crossover happens. The application requires high durability and if possible no risk of crashing or freezing. 
 
i enrolled in a PLC course to see if thats the right way to going about it, but it seems its more for industrial automation and the form factor of these PLC's seem to be more in line with server rack stuff. i intend on having a PCB board made with the required components once i know what components i should be looking at. I went to winsource electronics website and the sheer amount of components is extremely daunting, i am hoping maybe one of you could help me by pointing me at in the right direction of where to start learning. I appreciate your time!

brucehoult:

--- Quote from: Gumby83 on May 16, 2024, 10:13:20 pm ---Ideally with the lowest possible latancy.

--- End quote ---

Latency in single digit ns is easily possible.

A 4 stroke engine running at 10,000 RPM fires each spark plug once every 12ms or 12,000,000ns.

This is not "super fast". A 100 kHz 1970s microprocessor can do this.

Gumby83:

--- Quote from: brucehoult on May 16, 2024, 10:53:47 pm ---Latency in single digit ns is easily possible.

A 4 stroke engine running at 10,000 RPM fires each spark plug once every 12ms or 12,000,000ns.

This is not "super fast". A 100 kHz 1970s microprocessor can do this.


--- End quote ---


This is great news, i didnt know if it was possible. i figured time recieving the signal, to time outputting the signal would add miliseconds onto the original signal. It sounds like i could ask for more even, would it be possible to delay the start of a signal on 8 of the injectors by a milisecond or two with any accuracy? Could the signal input be a ground? and could the microprocessor duplicate that signal on a output accurately like a repeater?

cortex_m0:

--- Quote from: Gumby83 on May 16, 2024, 10:13:20 pm ---i enrolled in a PLC course to see if thats the right way to going about it, but it seems its more for industrial automation and the form factor of these PLC's seem to be more in line with server rack stuff. i intend on having a PCB board made with the required components once i know what components i should be looking at. I went to winsource electronics website and the sheer amount of components is extremely daunting, i am hoping maybe one of you could help me by pointing me at in the right direction of where to start learning. I appreciate your time!

--- End quote ---

FYI, WinSource is a "grey market" source, known as a component broker. They buy surplus components, and re-sell them. Component brokers are a common way to be bothered by fake components, and are rarely enough lower priced to warrant the risk.
Engineers usually like Digikey & Mouser as a starting point.


There are plenty of automotive microcontrollers out there. When you say "high speed analog", and "automotive" I think about the Microchip ATSAMV7 family. That's a pretty beefy product (300 MHz ARM core, 64 to 144 pins, up to 2MB flash, up to 384KB RAM).

There is probably something lower end you could use. But if you want to minimize latency before all else, you should start with something big. If you find the ATSAMV7 can do the calculations in 20ns but 200ns would be fine, you could step down from the 300MHz part to something rated for 48 or even 32 MHz.


--- Quote ---The application requires high durability and if possible no risk of crashing or freezing. 
--- End quote ---

The microcontroller choice has relatively little to do with this. There are automotive qualified microcontrollers out there, and you should probably use one. But the reason for "crashing and freezing" is almost entirely due to software problems.

Gumby83:
Thank you Cortex, good food for thought here.. i am running into a theme here.. my interpretation of fast is vastly different then what some of these top notch microprocessors are capable of. I honestly would be really happy with milisecond or so of response time. I would like to try to keep this project on the cheaper end so maybe i can get away with a 32mhz microchip. Any brand recommendations? id like to find something that can accept 10-16 inputs,16-24 outputs and runs off 12vdc.

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