Meaning
Numerical representation utilizes a fixed number of digits for both the integer and fractional parts of a value. Employing fixed-point arithmetic allows embedded processors without a dedicated floating point unit to perform complex mathematical operations. This method relies on scaling factors to manage the decimal position during calculation.
Computational Performance
Integer operations execute markedly faster than software-based floating point libraries on low power microcontrollers. By using fixed-point arithmetic, a firmware engineer can implement digital filters and signal processing loops with minimal latency. This efficiency is necessary for real time control in battery operated sensors.
Precision Constraint
Rounding errors and overflow risks require careful management of the word size and scaling. A developer choosing fixed-point arithmetic must analyze the dynamic range of the input data to prevent clipping or loss of significant bits. The selection of a Q format determines the trade off between the range of the numbers and the accuracy of the fractional part while ensuring that intermediate products do not exceed the register width during multiplication.
Logic Design
Standardizing the bit width across the entire signal chain simplifies the hardware interface between modules. Within fixed-point arithmetic, the alignment of the binary point is often hardcoded into the logic gates or the instruction sequence. This architectural choice reduces the silicon area required for the arithmetic logic unit.