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Appendix C - ZX-40 Series Hardware Reference
The ZX-40 devices are the 40-pin DIP package versions of the Atmel AVR ATmega32, ATmega644 or
ATmega644P microcontrollers that have been programmed with the ZX control firmware.  They offer the
same capabilities as the ZX-24 series plus access to 7 additional I/O pins.  In order to use the ZX-40
series devices you must add several additional components as described below.  In each of the diagrams
presented below, only a portion of the device’s 40 pins is shown.  Those that are not germane to the
circuit being discussed are omitted for clarity.
C.1 ZX-40 Series Specifications
The electrical specifications of the ZX-40, ZX-40a, ZX-40p are exactly those of the underlying ATmega
microcontrollers.  Rather than reproducing them here the reader is directed to the datasheet published by
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C.2 ZX-40 Series Required External Components
Power Source
The ZX-40 series devices need a regulated voltage source capable of providing at least 200mA of
current.  The voltage typically used is 5 volts but the device will operate between 4.5 volts and 5.5 volts. 
A recommended circuit is shown below.  A suitable heatsink will probably be required in most cases to
keep the regulator IC below its maximum operating temperature.  Consult the regulator datasheet for
more information.
ZX-40 Series Power Source
If you do not plan to use the Analog-to-Digital converter channels you can eliminate the inductor and the
two capacitors on the right side of the diagram.  In this case, pin 30 would be connected directly to the
power source (as are pins 10 and 30) and pin 32 can be left open.  Although not shown on this diagram,
the ground pins of the ZX-40 (pins 11 and 31) must be connected to the common ground of the system.
Clock Source
The ZX-40 series devices  require a clock source running at 14.7456MHz.  The easiest way to provide
this clock source is to connect a crystal of that frequency to pins 12 and 13 along with the necessary
capacitors.
The recommended crystal to use is ECS-147.4-20-4 (Digi-Key #X175-ND).  An alternate crystal in a
slightly larger package is ECS-147.4-20-1 (Digi-Key #X142-ND).  The capacitor value to use depends
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