LED Blink

This example demonstrates how to blink a LED on several FPGA board. It is one of the simplest possible BondMachine architectures, and is a good starting point for learning how to use BondMachine. The generated architecture is minimalistic, it only contains 3 instructions, 2 registers of a single bit, and some ROM memory for the program. The example originates from the following BASM code:

%section code .romtext
	entry _start    ; Entry point
_start:
	inc	r0	; Increment register 0
	r2o	r0,o0	; Write register 0 to output port
	j	_start	; Jump to _start
%endsection

%meta cpdef	cpu	romcode: code
%meta ioatt	testio	cp:cpu, index:0, type:output
%meta ioatt	testio	cp:bm, index:0, type:output
%meta bmdef	global	registersize:1

The example is simple, it increments a register and writes it to the output port. The program is executed in a loop, so the output port will blink. The example is also used to demonstrate the use of the ioatt meta-attribute, which is used to define the input/output ports of the architecture. The bmdef meta-attribute is used to define the size of the register in the architecture. The meta attributes are used to define the architecture, and the section and endsection directives are used to define the program code. The program code is written in BASM assembly language, which is a simple assembly language that is used to define the program code of the architecture.

if the following requirements are met:

• the FPGA tools for the specific board installed and in the PATH
• the board connected to the computer

then the example can be build and run using the following commands within the [boardname]_blink directory:

make apply
make program

Following is the output of the make specs command. It shows the details of the generated architecture in terms of the number of instructions, registers, ROM memory, and other details. It shows how tiny the architecture is, with only 3 instructions, 2 registers, and a small ROM memory.

Register size: 1
Processors:
  0:
    Domain ID: 0
    ROM width/Word size: 4
    ROM depth: 4
    RAM width: 1
    RAM depth: 1
    Registers: 2
    Inputs: 0
    Outputs: 1
    ISA:
        Istructions: 3(2)
        inc(3),j(4),r2o(4)
    Modes: ha
    ROM Code:
      000 - 0000 - inc r0
      001 - 1000 - r2o r0 o0
      002 - 0100 - j 0
    ROM Data: