Miller-Spec
Member
So I'm designing a module that reads and then sends analog and digital inputs over CAN bus.
I'm having trouble deciding how to tackle the digital input design.
In motorsport electronics these type of inputs normally have quite a bit of flexibility.
Some engine management systems incorporate all possible digital functions in every pin for maximum flexibility.
Everything from simple button switch inputs (active ground or active high mind you), to frequency measuring capability for speed inputs with waveform capture capability (positive and negative voltages).
The speed inputs will support both hall effect and inductive (variable reluctance) speed sensors which can sweep positive and negative sometimes over 100v..
Since they also have the ability to adjust voltage thresholds and hysteresis in software They can support almost any digital signal, with diagnostics for each input for detecting threshold and hysteresis noise and rejected pulses..
How can they accept so many different types of signals on any pin (some ecu's have up to 12 of these pins)? are they using high speed analog inputs and analyzing the signals and emulating a digital signal in software?
Are they using tons of digitals potentiometers and adjusting comparators? In the past I would design a different circuit for each of these features and give that pin a specific functionality.
Id just like to see how other people would approach this; I might be over thinking it. which I do often. I've yet to go very deep into digital input circuitry so far..
Thanks,
Xavier M
I'm having trouble deciding how to tackle the digital input design.
In motorsport electronics these type of inputs normally have quite a bit of flexibility.
Some engine management systems incorporate all possible digital functions in every pin for maximum flexibility.
Everything from simple button switch inputs (active ground or active high mind you), to frequency measuring capability for speed inputs with waveform capture capability (positive and negative voltages).
The speed inputs will support both hall effect and inductive (variable reluctance) speed sensors which can sweep positive and negative sometimes over 100v..
Since they also have the ability to adjust voltage thresholds and hysteresis in software They can support almost any digital signal, with diagnostics for each input for detecting threshold and hysteresis noise and rejected pulses..
How can they accept so many different types of signals on any pin (some ecu's have up to 12 of these pins)? are they using high speed analog inputs and analyzing the signals and emulating a digital signal in software?
Are they using tons of digitals potentiometers and adjusting comparators? In the past I would design a different circuit for each of these features and give that pin a specific functionality.
Id just like to see how other people would approach this; I might be over thinking it. which I do often. I've yet to go very deep into digital input circuitry so far..
Thanks,
Xavier M