Introduction¶
Chips is a high level, FPGA design tool inspired by Python.
Design components in C, design FPGAs in Python¶
A Chips design resembles a network of computers implemented in a single chip. A chip consists of many interconnected components operating in parallel. Each component acts like a computer running a C program.
Components communicate with each other sending messages across buses. The design of a chip - the components and the connections between them - is carried out in Python.
Chips come in three parts:
- A Python library to build and simulate chips by connecting together digital components using high speed buses.
- A collection of ready made digital components.
- A C-to-hardware compiler to make new digital components in the C programming language.
A quick example¶
from chips.api.api import *
#create a new chip
chip = Chip("knight_rider")
#define a component in C
scanner = Component(C_file = """
/* Knight Rider */
unsigned leds = output("leds");
void main (){
unsigned i;
while(1)
{
for(i=1; i<=0x80; i<<=1) fputc(i, leds);
for(i=0x80; i>=1; i>>=1) fputc(i, leds);
}
}
""", inline=True)
#capture simulation output in Python
scanner_output = Response(chip, "scanner", "int")
#add scanner to chip and connect
scanner(chip, inputs = {}, outputs = {"leds":scanner_output})
#generate synthesisable verilog code
chip.generate_verilog()
#run simulation in Python
chip.simulation_reset()
while len(scanner_output) < 16:
chip.simulation_step()
#check the results
print list(scanner_output)
[1, 2, 4, 8, 16, 32, 64, 128, 128, 64, 32, 16, 8, 4, 2, 1]
Work at a higher level of abstraction¶
In Chips, the details of gates, clocks, resets, finite-state machines and flow-control are handled by the tool, this leaves the designer free to think about the architecture and the algorithms. This has some benefits:
- Designs are simpler.
- Simpler designs take much less time to get working.
- Simpler designs are much less likely to have bugs.
With Chips the batteries are included¶
With traditional Hardware Description Languages, there are many restrictions on what can be translated into hardware and implemented in a chip.
With Chips almost all legal code can be translated into hardware. This includes division, single and double precision IEEE floating point, maths functions, trig-functions, timed waits, pseudo-random numbers and recursive function calls.
Python is a rich verification environment¶
Chips provides the ability to simulate designs natively in Python. Python is an excellent programming language with extensive libraries covering many application domains. This makes it the perfect environment to verify a chip.
NumPy , SciPy and MatPlotLib will be of interest to engineers, but thats just the start .
Under the hood¶
Behind the scenes, Chips uses some novel techniques to generate compact and efficient logic - a hybrid of software and hardware.
Not only does the compiler translate the C code into CPU instructions, it also generates a customised pipelined RISC CPU on the fly. The CPU provides the optimal instruction set for any particular C program.
By minimising the logic required to perform each concurrent task, designers can reduce power and area or cost. Performance gains can be achieved by increasing the number of concurrent tasks in a single device (tens in a small device to around a thousand or more large device).
While the code generated by chips is compact and efficient, die hard FPGA designers will be pleased to know that they can still hand craft performance critical data paths if they need to. There are even a few hand crafted components thrown in!