Timers Checks

[simoneruffini]

The previous maintainer of this project probably defined timers ARR (auto reload registers) wrongly.
In stm32 family counters prescalers and ARR start from 0 (means division by 1 or not counting).

All timers prescalers, ARR and compare registers must be double checked, e.g:
if ARR=500 than it probably must have been 499.
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