ETC FLASH

ASSP
F1-8X is available in a 128 pin LQFP for
use in ATA format cards and in a 100 pin
TQFP for CompactFlash. It is supplied in
volume to card manufacturers.
For designers who are beginning a flash
memory project Hyperstone offers a comprehensive tool kit for developing and
testing ATA Flash Memory and CompactFlash cards. It includes a hardware/
software test environment, firmware for
the Hyperstone’s advanced wear-levelling algorithm and ECC and other software development tools.
Hyperstone provide a full range of support services for flash card designers,
from technical help through to complete
design services.
Among the existing customers is Solid
State System Co, which uses the F1-8X in
its 3SPCF range of CompactFlash memory
cards.
Hyperflash® Cards
Hyperstone has developed its own Hyperflash families of ATA Flash Memory cards
and CompactFlash cards, using the F1-8X
to produce outstanding performance.
These are available in sizes up to 348
Mbytes currently. The latest flash memory
devices have made it possible to make
cards with capacities up to 992 Mbytes,
which these will be shipping soon.
Standard Hyperflash cards are intended to meet midto low-level production requirements, while special
Hyperflash cards are also available to meet special
requirements, such as extreme temperature ranges or
other demanding environments. They can also be integrated into other processor environments. The Hyperflash cards are also intended as working reference
samples for customer evaluation of the F1-8X flash
memory controller.
Business
Hyperstone provides two business models: Sale of controller devices and licensing of IP. Packed flash memory
controllers are available to customers ready for PCB
mounting. In special cases – typically high volume in
excess of 500k per year – Hyperstone also can make
the Intellectual Property in the F1-8X design available
under license. This could be to allow its implementation in a different process technology, where Hyperstone has experienced engineering resource available.
Alternatively, it could be to transfer the technologies
for flash memory control into a different environment.
For example, the F1-8X control functionality with the
wear-levelling and ECC can provide a quick route to
efficient integration of flash memory within an embedded application.
Flexibility and Support
The F1-8X just demonstrates how Hyperstone’s RISC/
DSP processor technology can be adapted to the needs
of flash card control. There are many other applications where the Hyperstone’s innovative and powerful
RISC/DSP architectures can provide dramatic increases
in performance and drastically cut time to market and
system costs.
TRADEMARKS: Hyperstone, Hyperflash, CompactFlash
Hyperstone AG, Am Seerhein 8, D-78467 Konstanz, Germany
Phone: +49 (7531) 98030 Fax: +49 (7531) 51725 E-mail: [email protected]
Website: www.hyperstone-ag.com
Flash Memory
Card Design - the
Hyperstone Way
Overview
Portable devices, such as PDAs, personal communicators, digital cameras,
MP3 players or voice recorders, require a storage solution that combines
non-volatility with low power requirements and high access speeds, all at
an acceptable cost. It is this market that the Flash Memory Card addresses.
As the cards have increased in capacity, so it has become more important to
provide built-in control functionality, including wear-levelling. Hyperstone
offers a complete solution - a flash memory controller development kit that
is “simply the best” - for a wide range of card formats, memory types and
applications.
Flash Memory Cards
Flash cards provide a third way in memory devices. Cheap, high-volume,
non-volatile storage has previously been provided by rotating magnetic
and optical memory such as hard disks and CD and DVD Read-Write systems. These are prone to mechanical problems, are power hungry and
can be slow, particularly when powering up from sleep or standby mode.
Lower capacity requirements are served by solid-state devices. DRAM and
SRAM are fast, but volatile and expensive. PROM and other devices are nonvolatile, but extremely slow when writing or programming.
Flash memory is a non-volatile solid-state memory that is affordable and
has acceptable read-write speeds. It draws considerably less power during
operations than rotating memory devices, is considerably more robust and
wakes rapidly from standby or sleep modes. Banks of flash memories
can be packaged in a PC Card format to create the solidstate equivalent of a hard disk.
With the increasing density of
these flash cards, managing
memory can quickly become
an overhead on a host processor. Instead, processing capability
has become built in, making flash
cards look even more like a standard hard disk to a host.
The two leading formats for flash
memory cards are the ATA Flash
Memory card in a PC II form-factor,
used in PDAs or personal organizers
and the newer, small form-factor CompactFlash™ cards used, for example, in MP3
players and digital cameras.
Design Options
Flash Card Controller Requirements
The controller manages the storage of data on the card and handles communication between the card and the host. It receives
data from the host and writes it to the bank of flash memory. It
responds to requests for data by reading from the memory bank
and passing data to the host. The host interface is defined by the
ATA/ IDE interface or the PC Card II/CompactFlash Services.
Support Interfaces.
To ensure that the data is correct the controller uses ECC (Error
Checking and Correction). During write operations, a calculation on the data to be stored generates additional code bytes.
These are stored with the original data in the flash memory
bank and, during read operations, are used in a reverse calculation to validate the data and correct bit errors.
After multiple read-write operations, individual bits in flash
memory can deteriorate. Optimal card life requires equal use
of each bit and “wear-levelling” algorithms, executed on the fly
during reading and writing operations, have been developed to
provide this.
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Since both ECC and wear-levelling
are carried out on the fly, a flash
card controller has to be able to
carry out these tasks at speeds
that match the operational speeds
of the host device.
A controller designed for a specific
card and manufactured in volume
could be implemented as an ASIC.
But if it is to have more general
application then the ASIC has limitations. It needs to be able to
cope with different flash memory
devices with different characteristics and different wear-levelling
requirements, with improved ECCs
and with different host interfaces.
Hyperstone has implemented the
F1-8X, a powerful single-chip controller solution as an ASSP (Application Specific Standard Product).
Based on the Hyperstone combined RISC/DSP processor it is
a high-speed, low-power, flexible
solution for a wide range of flash
card applications, up to 992
MBytes and beyond.
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Transfer Speed (KByte/sec)
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Random Read Time (ms)
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Source: Hyperstone benchmarking using QBENCH from Quantum Data
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The Design Solution
The 32-bit Hyperstone F1-8X ASSP implements
complete flash card functionality in a single chip
programmable device. (see diagram)
The external 16 bit wide interface to the host
device supports both ATA Flash Memory cards
and CompactFlash cards. It is in full compliance with the PCMCIA standards and has the
option of a True-IDE mode. The interface provides automatic selection of either 5.0V or 3.3V
power supply.
Once data has crossed the host interface, it is
passed to the flash memory interface where a
firmware implementation of the sophisticated 32
polynomial Error Correction Code algorithm generates the check bytes. During both write and
read operations, the Hyperstone implemented
ECC has no overheads.
The flash memory interface provides full support
for up to 16 memory devices from AMD, Hitachi,
Mitsubishi, Samsung, Toshiba and other compatible manufacturers providing up to 992 MBytes
of storage. It can achieve transfer rates of up
to 20Mbytes/sec. It also incorporates a voltage
regulator to provide the 3.3V supply needed
for flash.
The wear-levelling algorithm is executed in the
RISC core. The F1-8X device uses an extremely
sophisticated algorithm, developed by Hyper-
stone and now being patented, which equalises the
use of all locations for optimal card life. It supports the
wear characteristics of a wide range of different manufactures devices. Since the wear-levelling algorithm
is in software, the F1-8X device will be able to support new memories with different wear characteristics
with only minor code changes. Card life will exceed
100,000,000 write cycles with a MTBF in excess of
1,000,000 hours.
The 4 KByte Boot ROM holds the flash memory access
routines. It also has the routines for loading the operational code into the internal 16 KByte RAM of the
controller from the first memory areas of the flash
memory, where it is stored during manufacture. The onchip RAM is also used for intermediate storage during
wear levelling calculations. Internal memory reduces
overall component count and improves start-up and
run-time performance.
Typical power requirements are 29mA for reading to
memory and 28mA for writing. Idle mode power consumption is 5mA (typical) while in sleep mode the controller requires 100µA (typical).
Applications and Availability
To meet different applications, Hyperstone provides a
design kit and a range of products based on the F1-8X
device to meet different application requirements.