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November 2000 |
Revision 1.03 |
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Persistor Instruments Inc. |
© 1998 All rights reserved. |
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November 2000 |
Revision 1.03 |
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Persistor Instruments Inc. |
© 1998 All rights reserved. |
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This section introduces first time users to the hardware resources available on the CF1. It assumes you know little or nothing about the Motorola MC683xx family, CompactFlash, or the idiosyncrasies of programming embedded computers. The intent is to give you a quick overview of the capabilities you now have at your disposal. Click the accompanying links in each introductory paragraph to explore specific topics in greater detail or use the table below to quickly locate detailed hardware information.
- Block Diagram and Signal Connections
- Pin Descriptions and Notes
- Power Connections
- UART Connections
- QSPI Connections
- Counter/Timer Module
- Real Time Clock
- PLL System Clock
- Periodic Interrupt Timer
- Bus Expansion
- Flash and Virtual EEPROM
- Dimensions and Pad Placement
- Links to Manufacturers Data Sheets
The CF1 contains a Motorola MC68CK338 microcontroller, 1MB of flash memory that acts as the ROM for the BIOS, PicoDOS, and your custom applications, 256KB of static RAM which can be made non-volatile by simply adding a backup battery, a CompactFlash header to accommodate memory cards, a UART and RS-232 drivers for communications, a 3.3 volt linear regulator so you can run from battery supplies up to 20 volts, power management with protection circuitry to let the system drop into extremely low power modes, and three sets of pin strips to interface to external circuitry.
For a pictorial overview of the CF1, check out the Block Diagram and Signal Connections page.
For details and notes on pin connections, see both Pin Descriptions and Notes and Dimensions and Pad Placement
For detailed hardware specifications, look at the Physical, Environmental, and Electrical Specifications page.
The 68338 gives you a 2.5MIPS 32-bit CPU32+ based on the 68020 that uses a phase locked loop (PLL), frequency multiplied crystal oscillator that can dynamically adjust to workload. You can run it at 16MHz (and beyond) for number crunching or fast I/O, drop it all the way down to 160kHz to save power when there's not much to do, pick something in between to meet your exact needs, and even stop it completely to achieve sub-milliamp operation. The CPU32+ processor all but eliminates the need to program in assembler since C and C++ compilers map very efficiently to its architecture and instruction set.
The 68338 provides built-in system protection with a watchdog timer, bus, and clock monitors, and features a periodic interrupt timer that runs at a constant rate independent of the dynamic system clock speed. There's also a separate real time clock (RTC) module that runs from an independent crystal and power supply even when the main supply is off. The 16-bit data bus and 20-bit address bus is brought out to two 20-pin headers along with chip select signals that let you add memory and peripherals and setup the memory map and timing options in software.
32 multi-function I/O lines from the 68338 are brought out to 50 pin header. All can perform very fast digital I/O operations. Sixteen come from a counter-timer module (CTM) and can also perform a variety of period and pulse width measurement, input and output capture, and pulse width modulation functions. Three connect to interrupt signals and seven form a powerful multi-channel queued serial peripheral interface (QSPI) that allow expansion to hundreds of SPI devices such as A-D converters, D-A converters, digital I/O ports, MOSFET drivers, RS232/RS485/IrDA UARTs, USB nodes, MODEMs, pagers, LCD displays, EEPROM, serial flash, real-time clocks, PLL frequency synthesizers, and smart sensors.
The 68338 is supported by 1MB of fast flash memory and 256kb of fast SRAM, both of which are 16-bits wide and capable of running with zero wait states at 16MHz. The flash is rated for 100,000 erase/write cycles and provides several protection mechanisms to prevent accidental erasure or overwrites. One quarter of the flash is reserved for the PicoDOS and the CF1 BIOS and libraries, and the remaining 768kb is available for your programs or data storage.
The full 256kb of static RAM can be battery backed for several years with a single lithium coin cell which also backs up the real-time clock and power management circuitry that protects the SRAM from accidental writes when the power is removed. PicoDOS and the BIOS use 32kb of the RAM and the remaining 192kb is available for your applications.
Also in the memory category could be the CompactFlash memory cards that plug into the built-in header, but these are instead covered in the next section.
There is no disk drive. Instead the CF1 accepts a single CompactFlash (CF) memory card that looks for all the world like a conventional DOS disk drives but is much faster than floppies, a bit slower than hard disks, but much lower powered than either. The cards are fully DOS/Windows compatible and started at 2MB to 15MB, quickly jumped to 24MB then 48MB, and show no sign of stopping. The're mostly used as film for the new digital cameras, so there's a huge commercial market constantly pushing price and performance.
PicoDOS on the CF1 looks very much like DOS and mimics the standard DOS file and directory commands. You can execute ".RUN" files the same way ".EXE" files run on a PC, and even perform batch and autoexec operations with ".BAT" files. In your programs, you read and write to CompactFlash files using exactly the same standard C library functions you use on desktop computers. Start with fopen(), then fprintf() or fwrite(), fclose() to finish. Data files created on the CF cards can be read directly by PCs using a simple mechanical PC Card adapter or one the sub-$100 add-on readers to mount the CompactFlash as just another disk volume on your PC.
Even though we said there is no disk drive, we do have a companion product called the Persistor BigIDEA that lets the CF1 interface to IDE hard drives and flash cards to add up to 8GB of low power, hard disk storage. Take a look at our web site for details.
The 68338 has a queued serial module (QSM) that contains both a serial controller interface (SCI) which is really a fairly powerful UART, and a QSPI module for device level synchronous serial communications. We've tamed the QSPI with our Queued PicoBUS (QPB) software API, but it's still too complex for this overview. Suffice it to say that if you find an SPI device you want to work with, the tools exist to do this, but you've got some reading and studying to do.
The SCI UART on the other hand is fairly simple to grasp - it works much the same as the COM port on a PC, but can work at BAUD rates up to 230,400. The SCI receive and transmit pins feed into an RS-232 driver along with two other signals that provide CTS and RTS handshaking. When not transmitting, the RS-232 driver can be turned off to save power while still being able to receive data.
The 3.3 volt CMOS CF1 is inherently low power, but it has ways to drop the power even further. As described above, you can tailor the operating frequency to you needs and take advantage of the fact that power varies almost linearly with frequency. You can also take that to its limits and completely stop the clock to the CPU or the various sub-modules. Finally, the CF1 has a special suspend mode where power is pulled from everything except the RTC, SRAM, and wakeup circuitry.
The CF1's on board linear regulator can withstand input voltages from -20 to 20V operating in the input range of +3.6 to +20V. In addition to the reverse polarity protection the CF1's regulator has a thermal current limiting circuit. Because there is no reverse leakage you can override the CF1's regulator with your own regulated supply if applicable.
The CF1 also has many different options for low power modes. You can configure the CF1 to fit almost any power drain you wish, within the specification. The system clock can be adjusted in intervals of 320KHz to take advantage of the linear relationship between frequency and power consumption. Many of the integrated modules and peripherals can be individually turned off to save power, and the CF1 API gives you the access you need to control the power characteristics from your C programs. The most common modes are as follows:
All of the CF1's Digital I/O lines come out on Connector C, the 50 pin header. However, not all pins on Connector C can be used as I/O lines. Furthermore, there are many different kinds of I/O lines and they each have alternate functions that you may wish to use, which precludes them from use as a general-purpose I/O line.
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Tel: 508-759-6434 |
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Fax: 508-759-6436 |
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