Key Engineering Takeaways
- •Accelerometers measure gravity + linear acceleration; gyroscopes measure angular rate but suffer from integration drift.
- •Quadrature encoders output two 90-degree out-of-phase square waves (Channel A and B), enabling 4x decoding resolution and direction detection.
- •Place 100nF ceramic decoupling capacitors directly adjacent to every sensor VCC pin to eliminate high-frequency ripple.
Prerequisites
- • Digital logic signals
- • I2C and SPI basics
Quadrature Optical & Magnetic Encoders
Quadrature encoders generate two pulse signals $A$ and $B$ shifted by $90^\circ$ electrical degrees. When rotating clockwise, $A$ leads $B$. When rotating counter-clockwise, $B$ leads $A$.
By triggering hardware interrupts on **both rising and falling edges** of both channels, you achieve **4X resolution**:
$$\text{Effective Counts Per Revolution (CPR)} = \text{Base CPR} \times 4$$
If your motor has a 500 CPR disc connected to a 30:1 gearbox:
$$\text{Output Shaft Resolution} = 500 \times 4 \times 30 = 60,000\text{ ticks per rotation!}$$
Tags:#Sensors#IMU#LiDAR#Encoders#I2C#SPI#Hardware Noise