Hi Rauf,

this is also an important point. There are 3 ways:

1. Bad reliability:
You lost a lot of the profit because guarantee maintenance.

2. Moderate reliability:
You sell your equipment very cheap and make the most profit with maintenance.

3. Good reliability:
Your equipment need very low maintenance and you lost this profit source at the first view.
But the customer can be amazed, because today most other use the 2. way. And so he want to buy more from you and can promote you.
So this way can give the most profit in future.


How do good reliability ?

There is always a stormy weather outside the micro, especially on industrial environment. So you should use R, C, suppressor diodes on every input to let the storm (noise, high voltage spikes, e.g. from switching big motors) outside.
If speed not important, use integrating ADCs (e.g. dual-slope).

Also outputs must be proofed, especially to switch power loads (use relays or opto isolators).

And naturally your own power must be filtered. A clean VCC is the first condition for reliable working.

Nevertheless an external watchdog and reset circuit should be used to restart proper operation automatically in any case.


Software reliability:

Use never trial and error.
Calculate every step and than program it. And only, if you get the previous calculated result, accept it.
If not, you must try to find the fault and understand it.
Try never to build a work around around the faulty (most only as faulty assumed) routine.


... many other points of reliability ...


Its really a stony way until good reliability.


Peter