State machines
You will learn
How a synthesizer finds a state machine in your design, or refuses to.
Many designs are state machines: a register that holds the current state and logic that picks the next one. yosys looks for them and, when it finds one, can re-encode it. When it refuses, it says why. The widget draws the graph yosys extracted from real designs, a UART receiver and a SPI flash master, and shows a case it refused.
Try it
Open the uart_rx sample and count its states and transitions.
All lessons
Module 1 · The chip
What an FPGA is, which chip we use, and how its pins meet the board.
Module 2 · Numbers in hardware
Bits, trits and number formats, and what arithmetic costs in logic.
Module 3 · Your t27 program
Write a spec, test it, and see why compiling is not the same as being right.
Module 4 · Inside t27c
How the compiler reads a spec and what it writes, including the native t27b.
Module 5 · From spec to hardware
The Verilog t27c writes, the cells it becomes, and what one LUT does.
Module 6 · Reading synthesis
What yosys reports about your design, and which warnings matter.
Module 7 · Place, route, timing
Where the cells land on the die, and whether the clock is met.
Module 8 · The bitstream
How a routed design becomes the bits the chip loads, with no Vivado.
Module 9 · On the board
Ask the chip who it is, load the bits, and check them.
Module 10 · Lab: our own research
A number format of our own, an honest scoreboard, and a model's tables multiplied on the board.