P e r s i s t o r® C F 8

Multi-Megabyte CompactFlash Data Storage


Persistor Picture

Hardware Manual

November 1997 - Revision 12



Persistor® ...

The Persistor CF8 is Peripheral Issues' first 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. CF8 fills that void.

This particular Persistor records on CompactFlash cards, the most successful of the new breed of sub-PCMCIA sized recording media, targeting the cost conscious digital camera, PDA, and cellular phone markets. CF8 brings this bargain priced storage to the world of data acquisition.


What's Here

In this document you'll find a product overview, mechanical and electrical specifications, installation instructions, and links to other related information resources.


About Persistor CF8

Persistor CF8 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 CompactFlash memory cards. The CF8 connects to the Model 8 system bus with a single Ampliflex elastomeric connector (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 Peripheral Issues CompactFlash 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 CF8 takes less than 200uA.


CF8 Features


PicoDOS Software

The standard CF8 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 CompactFlash 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.


About CompactFlash

CompactFlash (CF) cards debuted in October 1994 as a new form factor standard for miniature, removable mass storage with initial capacities of 2, 10, and 15 MBytes. Fully compatible with PCMCIA (PC Card) and ATA standards, CF mates with a Type II PC Card adapter for immediate compatibility with current laptop and desktop computers. CF technology targets the very cost conscious digital camera, cellular phone, and audio recorder markets, providing your data logging application with competitive commodity priced storage right now, even lower prices in the near future, and drop-in expansion capabilities as flash capacities increase.

FlashCard and Adapter

About Peripheral Issues

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.

CF8 Specifications

Persistor CF8 with 15MByte Peripheral Issues Compact Flash Card



0 to 60 Degrees C (operating)

-25 to 85 Degrees C (non-operating)


8% to 95% non-condensing

Power Requirements


Operating Voltage

4.5 V

5.5 V

Idle Voltage

3.0 V

Write Current at 5V (1,2)

40 mA
65 mA

Read Current at 5V (1,2)

35 mA
40 mA

Idle Current at 5V

< 500uA

Idle Current at 3.3V

< 200uA

Note 1: Average currents over read/write period
Note 2: Typical figures show features set to minimum power mode, Maximum figures show features set to maximum performance mode.


Minimum Power
Maximum Performance

Write Single Sector (512 bytes)

12 mS typical
5.5 mS typical

Sustained Write (3)

40 KB/Sec
100 KB/Sec

Read Single Sector (512 bytes)

3 mS typical
2.8 mS typical

Sustained Read (3)

150 KB/Sec typical
180 KB/Sec

Note 3: Sustained read and write times do not include DOS file system overhead which will typically half those speeds.



51mm x 66mm x 9mm (2.0" x 2.6" x 0.35")


20 g (< 0.7 ounce)

CF8 Dimensions




Electrical Connections

The circuitry for the CF8 is proprietary to Peripheral Issues but the block diagram below shows all of the interface connections between the Model 8 and the CF8 and should provide designers of custom Model 8 hardware with all of the information required to successfully integrate the Persistor into their systems.


Pin out Location

Elastomeric Connectors

The CF8 connects to the Tattletale using only the SquishyBus pads shown at connector J2 in the diagram above. Both the CF8 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.

CF8 Option Jumpers

The CF8 board contains three hard-wired jumpers. One of these (JP3) is reserved for factory testing, another (JP1) is provided to resolve conflicts for possible future CF8 software enhancements, but the last (JP2) may need to switched to operate with other custom hardware or multiple CF8 systems (see below).

Jumper Location


The chip select jumper (JP2) 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 CF8, 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 JP2 on the left side of the CF8, cut the center trace and insert a jumper to select CS1 or CS10 as shown in the exaggerated drawing above.


Multiple and Panel Mount Applications

Connector J3 is a twenty conductor pin-strip (0.025" posts, 0.100" pitch) behind the CompactFlash connector on the CF8, which parallels the SquishyBus connections to allow stacked or cabled attachment of up to two additional CF8 cards for expanded or redundant data recording. Currently, the only way to panel mount the CF8 so that the card and ejector button extend beyond the panel requires two CF8s: one attached to the Model 8, and one cabled to connector J3. For volume applications, contact the factory for pricing and availability of unpopulated CF8 cards to serve as adapters from SquishyBus to the 20 pin cable connector.



Installing the CF8

The following components are required to get started with the CF8 and included in the basic package:

You'll also need a CompactFlash 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 CF8 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 CF8, perform a dry run and make sure you can talk to the Model 8 and see the TOM8> monitor prompt.


Disconnect any power and signal lines from the Model 8 and assemble the components as described. The CF8 normally attaches 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 the Ampliflex connector and the nylon spacers. This configuration allows for operation with an I/O-8 or custom expansion board using either SquishyBus or elastomeric connectors.

To use a CF8 with the PR-8 breadboard, the Model 8 and CF8 combination can be mounted in any of the four possible combinations as shown below. All configurations require trimming of the alignment boss on the SquishyBus connectors as described in the Tattletale manual. Assembly is accomplished with the longer 1 1/4" screws provided with the Persistor.

In the following diagrams, note that the PR-8 always has its communication jacks on the right and facing up. The Model 8 has its socket connectors facing away from the PR-8 in figures 1 and 2 and toward the PR-8 In figures 3 and 4. The connections shown in figures 2 and 4 are the only ones supported by hardware included with your Persistor. Figures 2 and 3 show configurations that provide the correct electrical connections, but which will require some mechanical design on your part to provide rigid attachment.


Testing the Installation

With the CF8 mounted, but no CompactFlash 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 CompactFlash card. Turn power back on, and at the TOM8> monitor prompt, use CrossCut or MotoCross to load "checkout.rhx" from the CF8 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 CF8, and the installed CompactFlash card.


Using the CF8

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 CF8 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 CF8 flash. Each time you write a block of data to the CF8, the CompactFlash 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 15MB card over one hundred times! With a 15MB Persistor, a well designed Model 8 program, and just six alkaline AA cells, you could easily power a four month mission storing 10 million 12-bit (packed) sensor readings sampled once every second.


Programming the CF8

This is as far as we take you in this hardware manual. The PicoDOS manual will take you through the software installation and show you how to work Persistor storage into your logging application.



Persistor Information Resources


Peripheral Issues

Links to the most up to date Persistor information and software updates are available online from Peripheral Issues home page and ftp site at:



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)


Onset Computer Corporation

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)


SanDisk Corporation

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)





Tel: 508-759-6434 LogoFax: 508-759-6436

Copyright (C) 1996

All products and names appearing in this document
are trademarks of their respective holders.