The Persistor AT8 is Peripheral Issues' second offering in a line of miniature, low power data recorders adapting high capacity, commodity priced data storage technologies to remote and embedded computing applications.
This particular Persistor mates to Onset Computer's Tattletale Model 8, a 2" x 3" 68332 powered single board computer, which is especially well suited to long term remote data logging, but until now, lacked a simple and economical high capacity storage strategy. Persistors AT8 and CF8 fill that void.
This particular Persistor records on SanDisk ATA style PCMCIA
cards, which are currently available with capacities up to 300MB. You
can stack up to four Persistor AT8 boards on one Tattletale Model to
achieve non-volatile storage beyond 1GB.
In this document you'll find a product overview, mechanical and
electrical specifications, installation instructions, and links to
other related information resources.
Persistor AT8 is a memory expansion board that mates to Onset Computer's Tattletale Model 8 providing very high capacity non-volatile storage for your data logging applications by using industry standard SanDisk ATA PCMCIA memory cards. The AT8 connects to the Model 8 system bus with a pair of Ampliflex elastomeric connectors (SquishyBus) and takes only a single chip select line away from the system resources. It also has an almost negligible impact on your system power requirements when used with SanDisk ATA Cards, spending most of its time idling at less than 500uA, and drawing typically 40mA for less than 12mS each time it writes a 512 byte block of data. When the Model 8 goes into 3.3V deep sleep, the AT8 takes less than 200uA.
The standard AT8 package includes PicoDOS, the Peripheral Issues
Card Or Disk Operating System software. The PicoDOS kernel and
command shell provides you with transparent access to DOS compatible
file access at both the programmer and user interface levels.
Reliable and secure recording with the minimum programming effort is
the focus of this software. You can realistically expect to recode
your RAM based Model 8 logger to add PCMCIA operation in just a few
hours. If your computer doesn't have PCMCIA slots, you can use the
included XMODEM and YMODEM batch offload facilities for error-free
serial port data recovery. Refer to the companion PicoDOS software
manual for details on the features and capabilities of the operating
system software.
SanDisk ATA PC Cards are standard PCMCIA form factor, non-volatile, flash memory cards that are compatible with the Persistor AT8 and with almost any Windows 95 laptop computer that features PC Card slots.
Peripheral Issues formed in 1995 to develop and market quality components for the embedded computing market. At Pii, we produce the development tools, software libraries, and hardware components that allow our customers to reduce design costs, increase quality, and help meet ever-shortening time-to-market objectives.
In addition to Persistors, other Peripheral Issues products include:
Crossbow, a cross-assembler and integrated development environment for the Macintosh. Crossbow features macro, conditional, and sectioned assembly, Intel, Motorola, and PIC object formats, local labels and includes, listings and symbol tables, programmers editor with multi-file and GREP search, terminal windows for test and debugging, and built-in support for most of the popular 8-bit microcontrollers.
MotoCross, a suite of utilities that transforms the native Metrowerks CodeWarrior C/C++ Compilers into powerful integrated development environments for embedded 68000 based microcontrollers. Using MotoCross, you can write and test code for embedded processors with the same speed and convenience you've become accustomed to in native code development.
|
Temperature |
0 to 60 Degrees C (operating) -25 to 85 Degrees C (non-operating) |
|
Humidity |
8% to 95% non-condensing |
|
|
|
|
|
|
Operating Voltage |
|
|
|
|
Idle Voltage |
|
|
|
|
Write Current at 5V (1,2) |
|
|
|
|
Read Current at 5V (1,2) |
|
|
|
|
Idle Current at 5V |
|
|
|
|
Idle Current at 3.3V |
|
|
|
|
|
|
|
|
Write Single Sector (512 bytes) |
|
|
|
Sustained Write (3) |
|
|
|
Read Single Sector (512 bytes) |
|
|
|
Sustained Read (3) |
|
|
|
Size |
62 x 94 x 10mm (2.42" x 3.68" x 0.39") |
|
Weight |
28 g (1.0 ounce) |
The circuitry for the AT8 is proprietary to Peripheral Issues but the block diagram below shows all of the interface connections between the Model 8 and the AT8 and should provide designers of custom Model 8 hardware with all of the information required to successfully integrate the Persistor into their systems.
The AT8 connects to the Tattletale using only the SquishyBus pads shown at connectors J1 and J2 in the diagram above. Both the AT8 and the Tattletale boards have gold plated pads which require only common-sense handling precautions. If the pads need cleaning from exposure to dust or finger oils, lightly wipe the elastomeric surface and the gold pads with a cotton swab moistened with isopropyl alcohol, and allow them to dry. Once connected, the Ampliflex connectors form a gas tight seal that prevents corrosion and requires no further maintenance.
The AT8 board contains one hard-wired jumper (JP2) which may need
to switched to operate with other custom hardware or multiple AT8
systems. The chip select jumper (JP1) connects by default to CS2, the
same select line used by Onset's PCMCIA adapter board. It's unlikely
you'll be using both that and the AT8, and most expansion hardware
designers are aware of potential conflict with the Onset adapter and
so avoid this line. If your hardware does use CS2, locate JP1 on the
top side of the AT8, cut the default
trace and insert a jumper to select CS0, CS1 or CS10.
The following components are required to get started with the
AT8 and included in the basic package:
You'll also need an ATA PC Card card (available from Peripheral Issues) and a Tattletale Model 8 (available from Onset Computer Corp.) to complete the installation and checkout.
The hookup for a AT8 is pretty straightforward, but any time you add new hardware to a Model 8, you should take the customary precautions of working with ground straps and a current limited power supply set to less than 10 volts and limited to less than 150 mA. Before connecting the AT8, perform a dry run and make sure you can talk to the Model 8 and see the TOM8> prompt.
Disconnect any power and signal lines from the Model 8 and assemble the components as described. The AT8 must attach to the memory side of the Model 8, which is the side opposite from the pin and socket connectors, and the different hole sizes for either end of the Ampliflex connector prevents incorrect installation. The #4 hardware affixes both of the Ampliflex connectors. This configuration allows for operation with an I/O-8 or custom expansion board using either SquishyBus or pin and socket connectors.
With the AT8 mounted, but no PC Card installed, reconnect the power and signal lines and repeat the test run to make sure you can still talk to the Model 8 and see the TOM8> monitor prompt. Turn off power to the Model 8 and insert a PC Card. Turn power back on, and at the TOM8> monitor prompt, use CrossCut or MotoCross to load "checkout.rhx" from the Persistor software diskette. On completion, hit 'G' to run the checkout program which will verify the installation and print out some information about your Model 8, the AT8, and the installed PC Card.
When adding non-volatile storage to your logger, you need to make accommodations for the extra energy required to write to the flash. There are two main components to consider. First, the AT8 adds an additional static current drain of about 500uA from the Model 8's 5 volt regulated supply (assuming you don't take advantage of the 200uA deep sleep). This has minimal effect on short duration experiments where fast sampling rates (> 1Hz) fill the card up before the long term effects matter. The second is the total energy required to write to the AT8 flash. Each time you write a block of data to the AT8, the PC Card card draws a fair bit of current for a short period of time. The following formula should help determine how much additional battery power your system will need.
2 mWh/MB + 2 Wh/month
For each megabyte of storage used, plan on adding 2 milliwatthours of battery, plus an additional 2 watthours of battery for each month of planned operation. The actual draw from the 5 volt supply is more like 1.6 mWh/MB + 1.8 Wh/month, but this formula above accounts for losses in the Model 8's switching regulator.
Specifications vary, but fresh alkaline 9V batteries are rated at around 4 to 5 watthours - enough power to fill a 150MB card over ten times! With a 150MB Persistor, a well designed Model 8 program, and just six alkaline AA cells, you could easily power a four month mission storing 100 million 12-bit (packed) sensor readings sampled ten times per second.
Links to the most up to date Persistor information and software updates are available online from Peripheral Issues home page and ftp site at:
http://www.periph.com ftp://ftp.periph.com/persistor/
The Peripheral Issues staff is available to handle product inquiries and technical support questions during east coast business hours at:
508 759-6434 (Sales) 508 759-6434 (Tech Support) 508 759-6436 (Fax) issues@periph.com
Onset Computer Corporation manufactures and sells the Tattletale Model 8 and offers a complete line of data logging solutions. You can reach them at:
508 563-9000 (Sales & Support) 508 563-9477 (Fax) sales@onsetcomp.com http://www.onsetcomp.com
Additional CompactFlash specifications and information about CompactFlash and the CompactFlash association is available online at SanDisk's web site at:
408 562-0500 (Sales) 408 562-0503 (Fax) http://www.sandisk.com
Fax: 508-759-6436