Atmel C51, User Manual

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Hardware Description
C51 Microcontrollers Demo Board User Guide 2-6
4119C–8051–3/03
Figure 2-4. C51/C251 Demo Board Powered by J2.
2.5 Board Layout
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On-Off
– Switches ON the power supply.
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Reset
– Resets the microcontrollers.
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INT1#
– Issues an interruption on microcontollers on INT1# pin.
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J8 Connector
– Configure hardware in Page Mode or Non Page Mode.
– for C251 microcontrollers. For C51 products, the configuration must be set to
Non Page Mode.
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Synchro IN
– Used to connect several C51/C251 Demo Boards together, provides global
reset / interrupt for all connected C51/C251 Demo Boards.
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Synchro OUT
– Only one power supply is needed but it may be able to deliver enough
current to supply all the C51/C251 Demo Boards.
– There are no rules to connect two boards together anyone of the two DB9
may be used.
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RS232
– Used to connect a terminal or through an RS232 serial communication port.
– This serial port can be used for displaying messages or for programming
external Flash memory.
Note: The cable that connect this RS232 Connector MUST be a pin to pin cable.
J18
ON
J1 Power Supply Connector
9V
PP3
J2
battery
NOT USED
(rechargeable or not)
LCD display