Key Engineering Takeaways
- •A 16-element transition table in Flash RAM enables direction and count updates in fewer than 10 assembly instructions.
- •Declare tick count variables as `volatile int64_t` and protect reads on 8-bit/32-bit MCU boundaries using atomic blocks.
- •Calculate speed via low-pass filtered numerical differentiation $\omega = \frac{\Delta \theta}{\Delta t}$.
Prerequisites
- • Hardware interrupts
- • Bitwise shifting
Lookup Table Fast ISR Implementation
By storing the previous 2-bit state and shifting in the new 2-bit state, a 4-bit index `(prev_state << 2) | new_state` instantly returns +1, -1, or 0 (invalid glitch).
Tags:#Encoders#Interrupts#ISR#State Machine#C++#Motion Control