mCs, DSPs,
and FPGAs
Realization technologies for robotics
In the Beginning,
• skipping ahead a bit...
Evolution
•
•
•
•
•
•
transistors
gates - SSI
~10 transistors
flip flops, registers, counters - MSI
sequencers, ALUs - LSI
microprocessors - VLSI
processors - ULSI
107 transistors
Micro-controllers and Singleboard Computers:
•A Micro-controller is an integrated circuit that contains many
of the same items that a desktop computer has, such as:
– CPU, memory, etc., but does not include any “human interface”
devices like a monitor, keyboard, or mouse.
•Micro-controllers are mostly designed for machine control
applications, rather than human interaction.
•Micro-controllers paired with all the peripherals they need to
be self-sufficient, such as the Basic Stamp II IC, are
sometimes called “single-board computers.”
microControllers - mCs
• Simplified processors/sequencers
• Intended for “embedded”applications
– cell phones, VCRs, washing machines,
toaster ovens, etc.
– single-chip solutions
• or maybe a few chips...
• Inexpensive (!)
– < $1.00 at the bottom end
– < $100.00 at the top end
mCs
• Programmable
– but typically only programmed once...
• “reasonable” performance
–
–
–
–
4 bit (passe’)
8 bit, 16 bit
32 bit (yes, but get real)
64 bit ? (dope-slap deserved)
• internal memory
– bytes -> kbytes of RAM
– kbytes of PROM, EPROM, EEPROM, Flash
mCs
• speed
– 2 -> 20 MHz
• faster (of course) and slower devices available
– remember, speed a power (watts)
• typically, 4 clock cycles per instruction cycle
• external ports
–
–
–
–
parallel (8 -> 24+ lines)
serial
timer/counter
analog (input; 8 bit typical)
• some devices have multi-channel analog-mux
mCs
• packaging
– 8 pin SOIC -> 400+ ball BGA
– and everything in between!
• programming
–
–
–
–
–
assembler, C
Basic (?)
Java
Pascal
pBasic, etc.
Lisp?
Prolog?
Microcontroller board
examples
• Motorola 68HC11 based boards:
–
–
–
–
Handy Board
FingerBoard
BotBoard
MiniBoard
68HC711E9CFN2
• 512 bytes RAM
• 512 bytes EEPROM
• 12 kbytes PROM
– containing modified-Buffalo kernel
• 16 bit address, 8 bit data
– 16 bit internal
• 8 analog in (8 bit ADC)
• serial I/O, timers, counters
• 8 MHz crystal; 2 MHz cycle
Microcontroller Board Example that
is presented in detail in Martin’s
textbook
• Handy Board
– Perfect for small
robots
– Easy to develop
software
mCs - why might you want one?
• dedicated application
– monitoring, control
• complex sequential function
– programmed in C
• low-medium performance
• low cost
• CLEO-II.5 silicon power system had over 5 dozen HC11’s
– approximating the intellectual capacity, and temperament,
of a 2-year old
Microcontroller Example that is our
main low-end project platform
•Basic Stamp
Another example of a
microcontroller
– Basic Programming Language
– Full documentation and examples online
– Basic Stamp IIe has the most programming space
Microcontroller that is even better
and was used in the Skeleton robot
•OOPic
– Object oriented
(VisualBasic)
– Full documentation
and examples
online
Another example
BASIC Stamp
• Many pre-defined functions
• Cost-point: $34 - $99
• Starter kit for $149
Original BASIC Stamp from
Parallax
• 256 bytes EEPROM
– 80-100 lines of PBASIC
• 16 bytes of RAM
– bytes, not kbytes!
• 8 bit parallel port
• serial port
• 4 MHz
The Basic Stamp
Microcontroller usage
Basic Stamp II (BSII)
•2048 Bytes of EEPROM(non-volatile)
- Clock speed of 20 MHz.
- Holds 600 lines of code in EEPROM
- executes an average of 4000
instructions/sec
- 32 Bytes of Ram(16 of it for variable
storage)
- 16 I/O pins, plus two synchronous
serial pins
- Programmable with a PC/Mac through
a serial connection with PBasic.
The Board of Education
• BSII micro-controller
• bread-board
• power supply
• 9 volt connection
• serial cable
Many boards can work together with
micro-controller boards
Foundation Controller
Motherboard
PIC
Microchip
(Peripheral-Integrated
Controller)
• Wide variety of sizes in chip
family
• Very low cost: $4-$20 per chip
• High speed
• Programmable in C
What is needed to use a PIC?
• Software
– MP-Lab development
environment
– A C-compiler
• PIC-Start Plus
programmer
• UV chip eraser for
some chips
Pin diagram PIC 12c672
Pin 1 Positive power
(3-5V DC)
Pin 2 Digital input/output
Pin 3 Digital i/o, Analog in
Pin 4 Digital input only
Pin 5 Digital i/o, Analog in,
counter-timer
Pin 6 Digital i/o, Analog in
Pin 7 Digital i/o, Analog in
Pin 8 Ground
How to use a PIC?
•
•
•
•
•
Define, step-by-step, the desired behavior
Choose a chip with appropriate I/O lines
Build a board
Write the program
Test and debug, test and debug
PIC16C58A
•
•
•
•
•
•
73 bytes RAM
2 kbytes UV-erasable EPROM
12 I/O pins
timer/counter
18 pin DIP
20 MHz crystal; 5 MHz cycle
Digital Signal
Processors - DSPs
• Essential difference from the microprocessor:
– DSPs are designed for high performance,
repetitive, numerically intensive tasks
• Integer and floating point devices available
– integer more common, less expensive
• besides, just multiply your floats by 1000,
and you have integers
DSPs - what is good about them?
• strong numeric
architecture(s)
– single cycle multiplyaccumulate
– parallel units (SIMD)
• specialized addressing
modes (no overhead)
– pre- and post- modification of
pointers
– circular addressing
– bit-reversed addressing (for FFT)
• on-chip memory
– multiple memory access
architecture
• several accesses per cycle
DSPs features
DSPs - more features
• specialized execution control
– tight loops do not require (repeated) instruction fetch
– conditional testing and loop-breaks built-in
• does not cost extra instruction to loop
• deep pipelines
– TMS320C6200 has an 8-deep pipe
• “wide” operation
– VLIW - very long instruction word
– many units (numeric, instruction, memory, other)
controlled by single (complicated) instruction
DSPs - architectures
• von Neumann - shared program/data memory
• Harvard - separate program memory
and data memory
• modified Harvard - get one operand from data
memory and another from program memory,
in the same cycle
• Super Harvard Architecture
– ‘cause SHARC sounds cool!
• TigerSHARC
SHARC !
DSPs TMS3
20C62
00
DSPs - hard to program
• keeping the pipe full,
• keeping the many units busy,
• squeezing out performance…
• is really difficult!
– Assembly language
– “emulators” which measure device performance
– no substitute for experience
DSPs - why might you want one?
• dedicated (or not) application
• “simple” sequential function
– with strong loop structure
– best programmed in assembly language
• but C tools are getting better
• high performance
– massive throughput!
• medium-high cost
– 1200 MIPs for under $50
– 2400 MIPs for $250
Programmables Once
• ROM
– read only memory
– mask programmed
• PROM
– programmable read only memory
– fuse/antifuse
– one-time programmable
Programmables - A few times
• EPROM
– erasable programmable read only memory
– UV light (chases charge off of floating gate)
– all or nothing
• EEPROM
– electrically erasable programmable read only memory
– all or nothing
• “Flash”
– EEPROM-like, but page-at-a-time erase
Programmables
• but why limit yourself to address -> data ?
• programmable array logic - PAL
– outputs = (mostly) combinatorial function
of inputs and other outputs
• 16L8
– 8 outputs
» 6 of the outputs can be fed back as inputs
– 10 simple inputs
– out = (a&b&!c) + (d&e) + !f + …
» up to 16 terms ANDed
» up to 7 product terms ORed
Programmables
• programmable logic device - PLD
– AND/OR array
– feeding “macrocell” of flipflop/pass-through
• and selectable feedback
– 22V10 (next slide)
• complex PLD - CPLD
– lots of PLDs in one chip
Examples of programmable
architectures
(Field) Programmable Gate
Arrays
• field programmable gate array - FPGA
– two common architectures:
• sea-of-PLDs
– e.g. Altera MAX 7000, MAX 9000
• sea-of-little look-up tables, feeding flipflops
– e.g. Xilinx XC4000, XC5200
• but of course, marketting pressure forces
everyone to sell everything
– Altera FLEX 8K look-up tables…
– Xilinx XC9500 sea of PLDs…
• Actel, Altera, AT&T, Cypress,
QuickLogic, Xilinx
MAX (Cypress)
Xilinx
FPGAs
• sizes
– 103 to 106 “gates”
• almost meaningless metric
• low-end = 3.2 x 22V10
– ~30 “gates” per AND/OR/macrocell?
• Speeds
– 50 MHz to 200+ MHz
• packaging
– typically SMT
• QFP, BGA
– 100 to 400+ “pins”
FPGAs - volatile vs nonvolatile
• nonvolatile
– EEPROM-like
• configuration held in floating-gate cells
– ready on power-up
– ~103 reprogram cycles
• so you can make a few mistakes…
– typical for sea-of-PLD devices
• smaller number of larger blocks
• more complexity per block
• lower % utilization
– as it that means anything
FPGAs - volatile vs nonvolatile
• volatile
– SRAM-based configuration †
• must be loaded on every power-up
– XC5202 -> 3000 gates, 42kbits of config = 42 ms (serial)
– †giant shift register - nothing “random access” about it!
– “unlimited” reprogram cycles
• limited by whatever holds the configuration data
– typically a tiny 8 pin serial (EE)PROM
– typical for sea-of-little look-up tables devices
• larger number of smaller blocks
• less complexity per block
• higher % utilization
FPGAs which one is right for you?
• If your function fits/works, go with it!
• in-system reprogrammability
(volatile or non) is a powerful ally!
– Allows “reasonable” mistakes to be corrected
simply by recompiling/reloading
• pick a device larger/faster than you need
– don’t expect to use more than 50% of the gates
• you may use them all, but don’t expect to!
• try to use a single clock for everything
FPGAs - why might you want one?
• Anywhere you might use a bunch of chips
– or a printed circuit board, or several...
• SoC - “System-on-a-chip”
• Complex parallel function
– programmed in HDL
• hardware description language
• Low -> high performance range
• Low-medium cost
– smallest is < $1.00
– largest are < $500.00
• for a million “gates” :-)
Previous Projects
• 1. Review material from ECE 171 and ECE 271 about
logic circuits, microprocessors and PLDs.
• 2. Find on Internet data sheets of top companies that
produce processors or programmable devices that may
be used in your robotic project this year.
• 3. Learn about programmable devices and boards that we
have in the lab. Dr. Greenwood has the whole FPGA lab
with programming tools and interfaces as well.
• 4. For the following tasks: robot theatre, robot soccer,
robot sumo, biped robot walker, analyze the best choice
of microcontrollers or other devices to implement
control.
Sources
•Curtis Bahn, RPI
• J.E. Wampler
•Michael Rodemer, University of Michigan, School of Art and Design
•Physics and Media Group, MIT
•Josh R. Fairley
•Dr. Raymond S. Winton
•Mike Haney, University of Illinois
•Steve Benkovic, Cal State University ,
Northridgehttp://homepage.mac.com/Sbenkovic s.benkovic@ieee.org
•Franklin Alioto, Christine Beltran, Eric Cina, Vince Francisco, Margo Gaitan,
Matthew O’Connor, Mike Rasay.
•Kenneth Chin and Prang Chim
• Dr. Jim Ostrowski, Bob Miller, Wally Szczesniak, Terry Kientz,
Brett Balogh , Siddharth Deliwala, John Bowen,
Darnel Degand, Kapil Kedia, Adrian Fox, Christopher Li