The question that I asked in the technical support Mikrotik and they could not answer and asked to ask this question on forum … Actually a question:
What is the source of IRQ 18 on board RB493G?
I almost got run a temperature sensor and voltage on the board RB493G remained just that, because we do not know what needs to generate IRQ 18 and try to emulate it with an interval timer to 20ms and fail with it (measurement go, the linear dependence is, but in a very narrow range and with a huge load on the processor and range is repeat. Most likely it is strob through IRQ and not timer) sad.
Give whatever they can because I am at a dead end and where to dig further do not understand … Thank you!