Transcript Rapid Prototyping with PLDs

Rapid Prototyping with PLDs
4th & 7th October 2005
Contents
1.
PLD versus ASIC
2.
Definitions:
a)
b)
3.
PLD
a)
b)
c)
d)
e)
4.
Rapid prototyping
PLD
Types of PLDs
How PLDs remember their configuration
PLD Advantages
PLD Suppliers
PLD Programming Languages
From Verilog to PLD prototyping
PLD versus ASICs
• ASICs – Application Specific ICs
DEFINITIONS
• Rapid Prototyping
– “Pencontohsulongan cepat”.
– Why do it?
• Saves cost.
• To test and verify functionality of a design, before
the actual chip is fabricated.
• PLD
– Programmable Logic Device.
PLD
• A programmable logic device.
– Programmed by the customer.
• An electronic component used to build digital
circuits.
• Has an undefined function at the time of
manufacture.
– Must be programmed before it can be used in a
circuit.
• PROM and EPROM are also considered a PLD
if they contain program codes (not just data).
PLDs
• A single PLD is able to replace a circuit
that consists of a few 7400-series TTL ICs.
• Function of the PLD is assigned during
programming of the device, i.e.
configuration.
– This function may be changed during
reprogramming (reconfiguration) of the PLD.
Programmability of PLD
1. OTP, One-time Programmable
•
PROM
–
Uses fuse links
2. Re-programmable
•
Able to store logic design in:
–
–
–
–
EPROM – uv erasable
EEPROM- electrically erasable
SRAM
Flash memory
Types of PLDs
1. SPLD
a) PAL (Programmable Array Logic)
–
The first PLD, introduced by Monolithic Memories, in 1970s.
b) PLA (Programmable Logic Array)
c) GAL (Generic Array Logic)
–
Invented by Lattice Semiconductor.
2. CPLD
•
For bigger logic circuits, it can replace thousands, or
even hundreds of thousands, of logic gates.
3. FPGA
•
•
Based on gate-array technology.
“Field” – an engineering term for the world outside
the factory, i.e. where the customers are.
Which PLD to choose?
• Based on:
–
–
–
–
–
–
Number of gates available, i.e. device capacity.
Speed.
Cost.
Volatility.
Power consumption.
Number of I/O pins.
• FPGAs and CPLDs are equally good choices for
a particular task.
Which PLD to choose?
• CPLD: thousands to
tens of thousands
gates.
Switch Matrix
• Determines
interconnection of
logic block with the
routing wires.
Max7128S
Floorplan
Which PLD to choose?
• FPGA:
tens of
thousands
to several
million
gates.
• Xilinx
Virtex – 8
million
gates.
Flex10k
Floorplan
Interconnection Switch Box
• The
programmable
switches will
determine
whether or not
a horizontal
line is
connected to
the vertical line
intersecting it.
• What makes
this possible?
FPGA
• FPGA versus MPGA (Mask Programmable
Gate Array).
• Configuration is volatile, and must be
reloaded each time on power-up.
– Use external PROM or EPROM to store
configuration data.
• Configuration may be changed if a
different functionality is required, via
reconfiguration.
FPGA
• Contains programmable logic blocks, and
may include programmable interconnects
and switches
FPGA Applications
•
•
•
•
•
•
•
•
ASIC Prototyping
DSP
Aerospace and defense systems
Medical Imaging
Computer Vision
Speech Recognition
Cryptography
Bioinformatics
Other types of PLDs
1. Reconfigurable systems
– Microprocessor circuits that contain some
fixed functions and other functions that can
be altered when the processor is running.
– Self-altering systems.
– The reconfigured FPGA can even test the
host system that it is embedded, i.e. BIST,
Built-in Self Test.
– Includes “internet reconfigurable logic, IRL”.
Other types of PLDs
2. Flash
– An EEPROM chip.
– Can erase memory in "in a flash“.
– Used for storage modules such as USB
drives, digital camera, memory cards and fax
machines.
– Flash BIOS chips replaced ROM BIOS chips
in PCs so that the BIOS could be updated in
place (on board) instead of being removed
and replaced.
FLASH
MEMORY
How PLDs remember their
configuration
• Anti-fuse
– Normally open, until a programming current (~5mA) is forced
through it.
• EPROM cells
– MOS transistor that is switched on by trapping an electric charge
permanently on its gate electrode. The charge remains for many
years and can only be removed by exposing the chip to strong
ultraviolet (uv) light.
• EEPROM cells
– Also uses MOS transistor, but the charge trapped on the gate
electrode is removed by applying a voltage of the opposite
polarity.
• SRAM
• Flash memory
PLD Advantages
• New chip designs can be tested and easily
modified, without involving expensive
photomask costs for chips completed in a
semiconductor fab.
• Memory-based PLDs can be
reprogrammed over and over, which
allows for working products to be
upgraded at the user’s site.
PLD Programming Languages
Currently:
– Verilog HDL
– VHDL (Very High Speed IC HDL)
– Altera HDL
Used to be:
– ABEL
– CUPL
– PALASM
PLD Suppliers
•
•
•
•
Altera
Xilinx
Atmel
Actel
•
•
•
•
AT&T
Lattice
Cypress
Quicklogic
From Verilog to PLD Prototyping
PLD Programming
• Functional simulation success?
• Synthesis – produces netlist, in EDIF
(Electronic Design Interchange Format)
format.
• Place & Route – mapping the actual
structure described in the netlist onto
actual macrocells, interconnections and IO
pins of the PLD. This produces a
bitstream, i.e. binary data to be loaded
onto the FPGA or CPLD.
PLD Programming
1. Uses “device programmer”.
2. Devices that are EEPROM or flash
based technology are in-circuit
programmable, i.e. the additional circuitry
that is required to perform device (re)
programming is provided inside the
FPGA or CPLD itself. This is done with
the aid of a JTAG interface or from onboard embedded processor.
Downloading using
the
Byteblaster Cable
The Altera UP1 Download Board
Questions
1. Discuss the advantages of using FPGA as
compared to standard ICs, like the TTL 7400
series and ASICs.
2. Name other forms of design entries besides
HDL.
3. How is non-volatile data held for an FPGA
device?
4. What are the advantages and disadvantages of
the volatility characteristic of the FPGA?
5. Name applications of reconfigurable hardware.
6. For the Max7128S and Flex10k,
a)
b)
c)
d)
How many gates does the device has?
How many I/O pins?
What is the speed of the device?
Sketch and label its floorplan with the
programmable elements inside it.
Tip: Use data sheets which you can obtain from Altera’s website.
What do you think?