NK Labs, LLC

Suppose you need a fast serial link between one low-end FPGA and another. Which protocol would you use? You might consider SPI or I2C, but they both use multiple wires. You could choose asynchronous serial / RS-232, but then you need accurate clocks. Cheap FPGAs have built-in clock oscillators, but they are not very accurate, especially over the full temperature range. A simple solution is to use PWM: it's self-timed (so only needs a single wire), and does not require accurat