ECE 448 – FPGA and ASIC Design with VHDL

Lecture 14

PicoBlaze Instruction Set

2ECE 448 – FPGA and ASIC Design with VHDL

Required reading

• P. Chu, FPGA Prototyping by VHDL Examples

Chapter 15 PicoBlaze Assembly Code Development

Recommended reading

• K. Chapman, PicoBlaze for Spartan-6, Virtex-6, and

7-Series (KCPSM6)

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PicoBlaze-3 Programming Model

ECE 448 – FPGA and ASIC Design with VHDL

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PicoBlaze-6 Programming Model

ECE 448 – FPGA and ASIC Design with VHDL

FFC

FFD

FFE

FFF

Bank ABank B

Syntax and Terminology

Syntax Example Definition

sX

KK

PORT(KK)

PORT((sX))

RAM(KK)

s7

ab

PORT(2)

PORT((sa))

RAM(4)

Value at register 7

Value ab (in hex)

Input value from port 2

Input value from port specified by register a

Value from RAM location 4

Addressing modes

Direct mode

ADD sa, sf

INPUT s5, 2a

sa + sf sa

PORT(2a) s5

Indirect mode

STORE s3, (sa)

INPUT s9, (s2)

s3 RAM((sa))

PORT((s2)) s9

s7 – 07 s7

s2 + 08 + C s2

Immediate mode

SUB s7, 07

ADDCY s2, 08

PicoBlaze ALU Instruction Set Summary (1)

PicoBlaze ALU Instruction Set Summary (2)

PicoBlaze ALU Instruction Set Summary (3)

Logic instructions

1. AND AND sX, sY

sX and sY => sX AND sX, KK

sX and KK => sX

2. OR OR sX, sY

sX or sY => sX OR sX, KK

sX or KK => sX

3. XOR XOR sX, sY

sX xor sY => sX XOR sX, KK

sX xor KK => sX

IMM, DIR

C Z

IMM, DIR

IMM, DIR

0

0

0

Arithmetic Instructions (1)

IMM, DIR

C Z

Addition

ADD sX, sY

sX + sY => sX

ADD sX, KK

sX + KK => sX

ADDCY sX, sY

sX + sY + CARRY => sX

ADDCY sX, KK

sX + KK + CARRY => sX

Arithmetic Instructions (2)

Subtraction

SUB sX, sY

sX – sY => sX

SUB sX, KK

sX – KK => sX

SUBCY sX, sY

sX – sY – CARRY => sX

SUBCY sX, KK

sX – KK – CARRY => sX

IMM, DIR

C Z

Test and Compare Instructions

TEST

TEST sX, sY

sX and sY => none

TEST sX, KK

sX and KK => none

COMPARE

COMPARE sX, sY

sX – sY => none

COMPARE sX, KK

sX – KK => none

C Z

IMM, DIR

IMM, DIR

C = odd parity of

the result

Data Movement Instructions (1)

LOAD

LOAD sX, sY

sY => sX

LOAD sX, KK

KK => sX

IMM, DIR

C Z

- -

FETCH

FETCH sX, KK

RAM(KK) => sX

FETCH sX, (sY)

RAM((sY)) => sX

Data Movement Instructions (2)

DIR, IND

C Z

- -STORE

STORE sX, KK

sX => RAM(KK)

STORE sX, (sY)

sX => RAM((sY))

DIR, IND

- -

Example 1: Clear Data RAM

;=========================================================

; routine: clr_data_mem

; function: clear data ram

; temp register: data, s2

;=========================================================

clr_data_mem:

load s2, 40 ;unitize loop index to 64

load s0, 00

clr_mem_loop:

sub s2, 01 ;dec loop index

store s0, (s2)

jump nz, clr_mem_loop ;repeat until s2=0

return

Data Movement Instructions (3)

INPUT

INPUT sX, KK

sX <= PORT(KK)

INPUT sX, (sY)

sX <= PORT((sY))

OUTPUT

OUTPUT sX, KK

PORT(KK) <= sX

OUTPUT sX, (sY)

PORT((sY)) <= sX

DIR, IND

DIR, IND

C Z- -

- -

Edit instructions - Shifts

*All shift instructions affect Zero and Carry flags

Edit instructions - Rotations

*All rotate instructions affect Zero and Carry flags

Program Flow Control Instructions (1)

JUMP AAA

PC <= AAA

JUMP C, AAA

if C=1 then PC <= AAA else PC <= PC + 1

JUMP NC, AAA

if C=0 then PC <= AAA else PC <= PC + 1

JUMP Z, AAA

if Z=1 then PC <= AAA else PC <= PC + 1

JUMP NZ, AAA

if Z=0 then PC <= AAA else PC <= PC + 1

Program Flow Control Instructions (2)

CALL AAA

TOS <= TOS+1; STACK[TOS] <= PC; PC <= AAA

CALL C | Z , AAA if C | Z =1 then TOS <= TOS+1; STACK[TOS] <= PC; PC <= AAA else PC <= PC + 1

CALL NC | NZ , AAA if C | Z =0 then TOS <= TOS+1; STACK[TOS] <= PC; PC <= AAA else PC <= PC + 1

Program Flow Control Instructions (3)

RETURN

PC <= STACK[TOS] + 1; TOS <= TOS - 1

RETURN C | Z if C | Z =1 then PC <= STACK[TOS] + 1; TOS <= TOS - 1 else PC <= PC + 1

RETURN NC | NZ if C | Z =0 then PC <= STACK[TOS] + 1; TOS <= TOS - 1 else PC <= PC + 1

Subroutine Call Flow

Interrupt Related Instructions

RETURNI ENABLE

PC <= STACK[TOS] ; TOS <= TOS – 1;

I <= 1; C<= PRESERVED C; Z<= PRESERVED Z

RETURNI DISABLE

PC <= STACK[TOS] ; TOS <= TOS – 1;

I <= 0; C<= PRESERVED C; Z<= PRESERVED Z

ENABLE INTERRUPT

I <=1;

DISABLE INTERRUPT

I <=0;

Interrupt Flow

ECE 448 – FPGA and ASIC Design with VHDL

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PicoBlaze Development Environments

ECE 448 – FPGA and ASIC Design with VHDL

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KCPSM6 Assembler Files

ECE 448 – FPGA and ASIC Design with VHDL

KCPSM6.EXE

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Directives of Assembly Language

ECE 448 – FPGA and ASIC Design with VHDL

Equating symbolic name

for an I/O port ID.

keyboard DSIN $0E

switch DSIN $0F

LED DSOUT $15

N/A

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Differences between Mnemonics of Instructions

ECE 448 – FPGA and ASIC Design with VHDL

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Differences between Mnemonics of Instructions

ECE 448 – FPGA and ASIC Design with VHDL

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Differences between Programs

ECE 448 – FPGA and ASIC Design with VHDL