16 payload bytes: declared rates change wire timeSPI · 1 MHz128.0 µs — 128 clocks; no added overheadI2C · 400 kHz382.5 µs — 153 clocks; simple writeUART · 1152001388.9 µs — 160 wire bits; 8N1Excludes device processing, software gaps and unmodeled protocol timing.