Command Processor Module

Vivado FPGA project implementing a command processor module with an AXI-based block design, GPIO-mapped control/status registers, BRAM access, and Integrated Logic Analyzer support for hardware debugging.

Building

Open Vivado, then run:

source scripts/build.tcl
open_project build/final.xpr

Running CPM Instructions

After generating the bitstream and programming the FPGA, load the CPM command script:

source scripts/run_cpm.tcl

Processor Tcl Commands

Command	Parameters	What it does
cpm_write_bram <index> <data>	index: BRAM word index 0-7 data: 32-bit value	Writes a 32-bit value into BRAM at 0xC0000000 + 4*index.
cpm_exec <opcode> <addr> [offset] [multiplier]	opcode: operation code addr: BRAM word index 0-7 offset: optional 8-bit offset multiplier: optional 8-bit multiplier	Executes one processor instruction, clears the execute bit, and reads the result.
cpm_read_result	None	Reads the 32-bit result register from GPIO.
cpm_cmd <opcode> <addr> <exec>	opcode: 3-bit opcode addr: BRAM word index 0-7 exec: 0 or 1	Builds the raw 8-bit command register value. Usually cpm_exec should be used instead.

Processor Opcodes

Tcl Variable	Opcode	Operation	Description
$OP_READ	000	Read	Returns the selected BRAM word unchanged.
$OP_COMP	001	Complement	Bitwise complements the selected BRAM word.
$OP_SHL	010	Shift left	Shifts the selected BRAM word left by 1 bit.
$OP_SHR	011	Shift right	Shifts the selected BRAM word right by 1 bit.
$OP_ADD	100	Add	Adds the offset value to the selected BRAM word.
$OP_SUB	101	Subtract	Subtracts the offset value from the selected BRAM word.
$OP_MUL	110	Multiply	Multiplies the selected BRAM word by the multiplier value.
$OP_MADD	111	Multiply-add	Multiplies the selected BRAM word by the multiplier, then adds the offset.

AXI Address Map

Address	Register	Description
0x40000000	CMDREG	Command register. Used to send opcode, BRAM address, and execute bit.
0x40000008	GPIO_RD	Result register. Used to read the processor output.
0x40010000	GPIO_OFFSET	Offset register. Used by ADD, SUBTRACT, and MULTIPLY-ADD.
0x40010008	GPIO_MULT	Multiplier register. Used by MULTIPLY and MULTIPLY-ADD.
0xC0000000	BRAM base	Shared BRAM base address. Word n is at 0xC0000000 + 4*n.