Thank you all for your responses
4 aarg :- I will omit the 10K pull up resistor and use the internal pull up resistor of arduino :)
Optocoupler will be mounted on the same PCB.
7 Wolframore :- The Output won't be indeterminate i feel as when Opto is off , Arduino will get ~+5V (Logic 1)(Due to internal pull up high resistor) and when opto is on arduino will get ~ 0(Logic 0)
8 Paul_KD7HB :- Paul the Truck will be having the standard 2x 12VDC (24VDC) battery only.
if you refer the article :- https://www.autobatteries.com/en-us/battery-testing-and-maintenance/car-battery-voltage-and-testing
it shows that when the battery is charged potential will be 12.6 VDC i.e (2 x 12.6 :- 25.2 V DC ) across battery terminal and while charging or during high throttle it can go up-to 14.7 V DC(29.4 VDC) .
Truck is Diesel truck hence while starting the truck , We observe a drop of potential of around 1 V DC hence on safer side I have mentioned 22 V DC .
Yes my system will be connected and is expected to work while starter motor is engage and starting the truck engine.
9 Wolframore :- Exactly I want my design to be fool proof , Kindly suggest to improve it's reliability
10 wvmarle :- you mean ,as I am using optocoupler the protection against negative transients won't be required (am i right in understanding your point?)
:- I will definitely remove the 10K pull up resistor.
11 railroader :- it's a diesel truck , with two 12V battery. (Thanks I will be using optocoupler )
12 Paul__B :- I will be using LM-2596-5 buck converter
:- I will be using PIC847 (4 packs opto coupler) , Optocoupler will be mounted on the same PCB as that of Arduino board
:- I did not exactly get your ground part kindly confirm if my understanding is correct :- You mean that i should separately route the optocoupler input ground and Optocoupler output ground. But what would be the benefit of it as the chassis ground and battery ground will be same (After Euro-4 all the chassis is connected with battery ground).
My Questions :-
1) LM-2596-5 Buck converter I am using is correct or some better alternative is available.
2) As suggested by Paul__B , What's would be the benefit of routing separate optocoupler input and output ground as ultimately the chassis and battery ground is same.
3) As suggested by wolframore :- Kindly suggest some protection circuitry that I can add to increase system robustness and reliability
4) LM 2596-5 voltage variation will be between (4.8 to 5.2 V DC) so should I connect it to VCC pin of Arduino ? ( as the RAW pin accepts voltage between 6V to 20V DC)