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145 Appendix E - ZX-1281 Series Hardware Reference The ZX-1281 series devices are the 64-pin TQFP package version of the Atmel AVR ATmega1281 microcontroller that has been programmed with the ZX control firmware. In order to use the ZX-1281 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-1281 Series Specifications The electrical specifications of the ZX-1281 series devices are exactly those of the ATmega1281. 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 | http://www.zbasic.net. E.2 ZX-1281 Series Required External Components The circuits described below represent the minimum external circuitry required to operate the ZX-1281 series devices. Depending on your application, you may need additional circuitry to take advantage of the capabilities of the ZX-1281 series device. In contrast to some other ZX devices, these devices do not require an external EEPROM for program storage. Rather, the compiled user program is stored in the ZX’s internal Flash memory. The maximum user program size is 60K bytes for the ZX-1281 and 124K for the ZX-1281n. Power Source The ZX-1281 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-1281 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-1281 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 64 would be connected directly to the power source (same as pin 21, etc.) and pin 62 can be left open. Although not shown on this diagram, the ground pins of the ZX-1281 (pins 22, 53, and 63) must be connected to the common ground of the system.