NK Labs, LLC

There have been interesting developments in the world of small FPGA's over the last five years. Tiny "chip scale" FPGAs under 4.5 mm x 4.5 mm containing a large number [6,000 (for Lattice Crosslink MD6000) - 8,000 (for the Intel/Altera MAX 10M08)] of LUTs have become available. This is equivalent to the largest Xilinx XC4000 series FPGA from the year 2000. In fact, these new FPGAs are much better; they have built-in configuration flash, which is capable of self-updating. They

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