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ZBasic Language Reference
169
ZX Microcontroller Family
Appendix E - ZX-44 Series Hardware Reference
The ZX-44 series devices are the 44-pin TQFP package version of the Atmel AVR ATmega
microcontroller that has been programmed with the ZX control firmware (VM version) or bootloader (natve
mode version). They offer the same capabilities as the corresponding ZX-24 series devices plus access
to 7 additional I/O pins. In order to use the ZX-44 series device you must add several additional
components as described below. In each of the diagrams presented below, only a portion of the ZX pins
is shown. Those that are not germane to the circuit being discussed are omitted for clarity.
E.1 ZX-44 Series Specifications
The electrical specifications of the ZX-44 series devices are exactly those of the underlying ATmega
microcontroller. Rather than reproducing them here the reader is directed to the datasheet published by
Atmel. It can be obtained from the Atmel website |http://www.atmel.com or from the ZBasic website
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E.2 ZX-44 Series Required External Components
Power Source
The ZX-44 series devices need a regulated voltage source capable of providing at least 200mA of
current. The voltage typically used is 5 volts but the ZX-44 series devices 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-44 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 27 would be connected directly to the
power source (same as pin 5, etc.) and pin 29 can be left open. Although not shown on this diagram, the
ground pins of the ZX-44 (pins 6, 18, 28 and 39) must be connected to the common ground of the
system.
Clock Source
The ZX-44 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 7 and 8 along with the necessary capacitors.
The recommended crystal to use is ECS-147.4-20-4 (Digi-Key #X175-ND). Alternate crystals are the
ECS-147.4-20-1 (Digi-Key #X142-ND) in a slightly larger package and the ECS-147.4-18-9 (Digi-Key
#XC-957ND) in a cylindrical package. The capacitor value to use depends somewhat on the layout (e.g.
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