NOTES ABOUT THIS SCHEMATIC
;* Author 		: Brady Mayes
;* File Name 		: e13_2_schematic.sch
;* Date			: June 28, 2005
;* Last Update		: June 28, 2005
;* Version		: 2.0.0
;* Support Telephone	: withheld
;* Support Fax		: withheld
;* Support E-mail	: brm016000@utdallas.edu
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The attached schematic is intended for use with the ISO2 Card Diagnostic Reader Project (project E013).

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EXTERNAL (UNSHOWN) DEVICES
==========================
JP1 is the connection to the LCD.  This schematic was designed for use with HD44780-compatible 16x2 character displays, and was tested with the Sharp LM16X21A and Lumex LCM-S01602DSR/A models.

JP2 is the connection to the card reader.  This schematic was designed for use with an ISO "Track 2" magstripe reader (supporting ISO 7810 and 7811, F2F magnetic encoding).  This circuit was tested with the Panasonic ZU-M2121S451 insertion reader.  The maximum data rate is assumed 1,772 bits per second based on card specifications.

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CRYSTAL FREQUENCY
=================
The software featured in the project E013 documentation was optimised for use with a 4.00MHz clock source.  The software will allow for a maximum 8% increase in clock rate before the first display errors result.  Further clock increases will require modification to the supporting software.

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BYPASS CAPACITORS
=================
Although not shown, 0.1uF bypass capacitors may be placed between the supply leads of the AVR controller, LCD display, and card reader module to suppress small voltage transients.

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7805 VOLT REGULATOR
===================
There are many varieties of 7805 (+5) regulators.  If your design is intended to use the LCD display's backlight, the model must support an average supply current of no less than 175mA.  Otherwise, the average current may be assumed to stay lower than 50mA.

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BATTERY
=======
The DC power supply (shown as "BAT1") should have low noise and an average value greater than the dropout voltage of the 7805 regulator.

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DATA BUS
========
The blue data bus shown connects the higher data bits of the display with the lower data bits of the AVR.  Pin "DB.4" from the display should connect to "PB.0" of the AVR; while "DB.5" connects to "PB.1" an so on.  The recommended bus length is less than 300mm.

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PINHEADERS
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JP1 and JP2 are generic connectors.  The recommended bus lengths are less than 300m.


Check http://www.geocities.com/digitan000  for more details.

12:53 AM 6/28/2005