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October 1998 |
Revision 1.03 |
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Persistor Instruments Inc. |
© 1998 All rights reserved. |
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October 1998 |
Revision 1.03 |
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Persistor Instruments Inc. |
© 1998 All rights reserved. |
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IntroductionThis manual provides instructions on how to quickly and safely start working with your new Persistor CF1. If you bought the Persistor along with a starter RecipeCard, be sure to read the Getting Started notes that come with the card. If you're building your own breadboard, pay particular attention to the Warnings and Precautions section.
To begin working with the Persistor, you'll need to feed it some power and get it talking to a communications program on your computer. The Persistor doesn't have standard power or communications jacks because it will ultimately be incorporated into your custom instrument where the size or placement of built-in connector would probably be inappropriate. Instead, the Persistor has three sets of double-row pins that mate to standard 0.1" headers. The large 50 pin strip (2x25) brings out all of the standard I/O connections, and the two 20 pin strips (2x10) bring out the bus signals used by more esoteric applications.
All of the CF1 pins are on 0.1" grids, so you could just plug the Persistor into any standard breadboard and wire in connections for the power supply and UART, though it's more likely you'll make your acquaintance by purchasing one of the Persistor "Recipe Cards". These are prototyping boards pre-fitted with UART and power jacks, a breadboard area, and usually a backup battery socket, and one or more specialty analog or digital I/O interface circuits.
The combination of a Persistor and Recipe Card let you quickly start working on your experiment goals without putting a lot of front-end effort into wiring up the hardware. In many cases, this will be all you need for the initial prototype, proof-of-concept, or feasibility studies. The Recipe Cards come with complete schematics, parts lists, and design notes for when and if you decide to move portions to your custom board.
If this is your first experience with a Persistor, we'd would greatly appreciate any feedback on how we can improve the introduction. Please jot down notes on any part that seemed awkward or unclear, or that you feel could use improvement and send them off in an email to info@persistor.com. Don't spell or grammar check and don't worry that you'll hurt our feelings or that your stating the obvious. It's only during this initial introduction that we are likely to get the responses we need to improve this for the next user.
Warnings and PrecautionsWe really don't want to dampen the excitement of exploring your new board, but there's some stuff you really ought to know. Even the old-timers may find something new to worry about with this new 3.3 volt system and its super suspend mode. Just take a minute to skim this short section and save the possible embarrassment and expense of having to admit you leaped before looking.
3.3V I/O: The CF1 is a 3.3 volt only system, and cannot tolerate any voltages above 3.6 volts on any of its I/O or BUS lines, except for the RS232 signals (RSTXD, RSRXD, RSCTS, RSRTS). Even momentary connection to 5 volt signals will likely result in permanent damage to the boards components. Do not attempt to get around this by running the board at 5 volts as the RAM, and especially the flash will suffer stress damage.
Suspend Mode: When the CF1 goes into suspend mode, all of the I/O and BUS pins (except for the RS232, /WAKE, and /SHDN) look like very low impedance current sinks with about a 1.3-1.8 volt forward drop. CF1 I/O or BUS lines being driven from off-board peripherals will try very hard (and succeed) at pulling these levels low, which is probably not what you want. Any I/O lines being pulled high to an external V+ source will be pulled down to this forward voltage drop. Both of these situations will consume lots of current which defeats the purpose of suspend mode.
Static Sensitive CMOS: Every component on the CF1 is CMOS and susceptible to immediate damage, or worse, premature field failures if you don't take precautions to guard against damage from static electricity.
Develop with a current limited power supply! You can save yourself a lot of grief by running the board from a bench supply current limited to about 100mA. Jumpers, test probes, and programming bugs make it very easy to send the CF1 into some horrible current sucking latchup and current limiting can keep a spurious slip from destroying your board.
Develop at low voltage! The CF1 onboard voltage regulator can handle +/-20 volt inputs, but nothing else on the board can. Just like current limiting, developing at around 4 volts is a good way to keep a simple slip from destroying your board.
Floating Inputs: Most of the I/O lines on the CF1 do not have onboard pull-up resistors, and most of these are left in their default input state at reset. CMOS floating inputs draw current in somewhat unpredictable fashion - nowhere near enough to do any damage, but enough to defeat the gains of some of the power saving modes. You should either pull unused I/O lines to VREG or GND, or force them to be outputs.
Don't Stick Probes in the Header Sockets: The header strips used in the RecipeCards are meant to accept 0.025" square posts. Anything else is likely to permanently deform the connectors and cause your system to fail or behave erratically. We did this here with a scope probe tip (0.037" diameter), and a customer did it with a miniature DMM probe (0.044" diameter). We both spent many frustrating hours searching for the source of bizarre problems. The deformation damage is quite visible, but only with the help of a microscope - and no, this would not be covered under the warranty.
Backup battery is required: The CF1 depends on a separate PIC microcontroller to manage startup, power-off watchdogs, suspend mode, and CF card changes. Even if you're not using the last three features, you probably want the CF1 to start up when you apply power - and that's not guaranteed unless there is voltage at the VBBK pin during power-up. If you really don't want to provide a backup cell, you can connect separate 3 volt regulator between your main supply and VBBK.
ConnectionsThe drawing above shows the top view of the connection strip we reference in this guide. The view is from the front side (looking at the CompactFlash header) with the 2x25 row I/O pin strip at the top. White silk screen on the board quickly identifies the pin orientation with the large white block defining the pin 1 location (also the BDM connection), and with small white squares surrounding every pin that's a multiple of five.
If your hooking up through a RecipeCard, refer to its Getting Started guide for where to connect power and communications cabling.
The drawing above shows about the simplest starting hookup for the CF1, but note that the backup battery is not optional. We strongly recommend that you experiment with your CF1 using a current limited power supply set to 4 volts and 100mA, though it will happily work from a 9 volt battery or simple AC-DC adapter. You only need to make three connections to your PC's RS232 comm port, though some communications programs want to see their DTR(4) tied to DSR(6) and RTS(7) tied to CTS(8).
Test RunSet your communications program for direct connection, 9600 baud, no parity, 8 data bits, and 1 stop bit. Apply power to the Persistor, and you'll probably see something like the following:
----------------------------- Persistor CF1 SN 10000 (C) 1998 Persistor Instruments Inc. www.persistor.com PicoDOS V2.01 ----------------------------- PicoDOS>
Depending on what's in the flash memory, you might also see something like the following:
----------------------------- Persistor CF1 Boot Monitor (C) 1998 Persistor Instruments Inc. www.persistor.com PBM338 V1.10 ----------------------------- == FLASH WRITE ENABLED == PBM>
Either of these means that your hookup is complete enough to go on the next phase and you've reached the end of the getting started section.
TroubleshootingIf you don't see one of these sign on messages, it means there's a problem with one of the following:
Communications software problems: The easiest way to verify the PC communications software is to disconnect the cable at the CF1 connection and use a jumper wire to short TxD(3) to RxD(2) where the cable had gone into the CF1. If the PC software is working at all, you should be able to type characters at the keyboard and see them appear on the terminal window. If this works, make sure that you've got the correct baud rate set (9600,N,8,1) and go on to the next step. If this doesn't work, you're going to have to get help or hit the software's manuals to find out how to make a direct terminal connection from your machine.
Comm connection problems: If jumpering works, then perhaps your cable swaps RxD and TxD. You'll need to either reverse the connection directly, try a different cable, or use a gender changing adapter to confirm this possibility.
Power connection problems: First confirm that all of your connections agree with the diagram above. Next confirm that power is going to, and getting into the CF1. Use a voltmeter to confirm that the supply voltage is getting to pin C13, that pin C11 is putting out 3.3 volts, and that pin C9 is also getting 3.3 volts from the jumper to pin C11. Next, put a current meter inline with C13 and confirm that some current is getting into the board. Depending on what software is trying to execute in the flash, the normal range will be from 2 to 50mA. If you see voltage at pin C13, but there appears to be no current drain, it's possible that startup software is immediately forcing the Persistor into suspend mode, so continue to the next step.
Installed software problems: As delivered from the factory, the CF1 should power up directly to PicoDOS and send the sign on message shown above. The CF1 has lots of options for automatically running your custom software at startup, and a perfect working embedded application when taken out of its normal operating context can look a lot like a faulty system. If you tie /IRQ5, which is pin 39 on connector C to ground while cycling the power, you'll force the CF1 into the boot monitor regardless of whatever else is in flash memory.
Hardware failure: If all of the above techniques fail to start the Persistor, contact us at the factory and we'll either suggest some additional tactics, or have you send the board back for repair. If you've got an oscilloscope, there's some notes you can make before calling to help in our diagnosis.
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Tel: 508-759-6434 |
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Fax: 508-759-6436 |
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