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Port 0 outputs the low byte of the external memory address, time-multiplexed with the byte being written or read. Port 2 outputs the high byte of the external memory address when the address is 16 bits wide. Otherwise the Port 2 pins continue to emit the P2 SFR content. All the Port 3 pins, and two Port 1 pins (in the AT89C52)are multifunctional. The alternate functions can only be activated if the corresponding bit latch in the port SFR contains a 1. Otherwise the port pin is stuck at 0.
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20:
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All four ports in the AT89C51 and AT89C52 are bidirectional. Each consists of a latch (Special
Function Registers P0 through P3), an output driver, and an input buffer. The output drivers of Ports 0 and 2, and the input buffers of Port 0, are used in accesses to external memory. In this application,
50:
Based on the Intel 8051 core, the AT89 series remains very popular as general purpose microcontrollers, due to their industry standard instruction set, their low unit cost, and the availability of these chips in DIL (DIP) packages. This allows a great amount of legacy code to be reused without
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Atmel has also created an LP (low power) series of these chips with a "Single Cycle Core", making the execution speed of these chips considerably faster.
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More recently, the AT89 series has been augmented with 8051-cored special function microcontrollers, specifically in the areas of
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microcontrollers, new product development has continued with the AT89 series for the aforementioned advantages.
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modification in new applications. While less powerful than the newer AT90 series of
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884:"Low Pin Count 8-bit MCU with A/D converter and 16 KB Flash Memory"
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Atmel's 8051 family product page, updated link 09/23/2012
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Intel 8051-compatible family of 8 bit microcontrollers
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1215:"AT89C55/55WD - Microcontrollers and Processors"
962:"AT89C5131A-M - Microcontrollers and Processors"
937:"AT89C5131A-L - Microcontrollers and Processors"
912:"AT89C5130A-M - Microcontrollers and Processors"
1505:"AT89LP6440 - Microcontrollers and Processors"
1480:"AT89LP4052 - Microcontrollers and Processors"
1455:"AT89LP3240 - Microcontrollers and Processors"
1399:"AT89LP2052 - Microcontrollers and Processors"
1240:"AT89EB5114 - Microcontrollers and Processors"
1137:"AT89C51RD2 - Microcontrollers and Processors"
1087:"AT89C51ID2 - Microcontrollers and Processors"
1062:"AT89C51IC2 - Microcontrollers and Processors"
1037:"AT89C51ED2 - Microcontrollers and Processors"
1012:"AT89C51AC3 - Microcontrollers and Processors"
987:"AT89C51AC2 - Microcontrollers and Processors"
699:"AT83EB5114 - Microcontrollers and Processors"
571:"AT80C51RD2 - Microcontrollers and Processors"
1864:
1798:"AT89S8253 - Microcontrollers and Processors"
1692:"AT89S4051 - Microcontrollers and Processors"
1636:"AT89S2051 - Microcontrollers and Processors"
1346:"AT89LP216 - Microcontrollers and Processors"
1321:"AT89LP214 - Microcontrollers and Processors"
1265:"AT89LP213 - Microcontrollers and Processors"
1112:"AT89C51RC - Microcontrollers and Processors"
859:"AT89C5115 - Microcontrollers and Processors"
805:"AT89C4051 - Microcontrollers and Processors"
752:"AT89C2051 - Microcontrollers and Processors"
674:"AT83C5136 - Microcontrollers and Processors"
649:"AT83C5135 - Microcontrollers and Processors"
624:"AT83C5134 - Microcontrollers and Processors"
8:
1583:"AT89LS52 - Microcontrollers and Processors"
1530:"AT89LS51 - Microcontrollers and Processors"
1717:"AT89S51 - Microcontrollers and Processors"
1162:"AT89S52 - Microcontrollers and Processors"
1871:
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1664:"AT89S2051/S4051 Preliminary Datasheet"
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7:
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1843:. You can help Knowledge (XXG) by
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1:
536:Port Structures and Operation
92:AT89 Series Microcontrollers
39:-compatible family of 8 bit
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43:(μCs) manufactured by the
724:"AT83EB5114 AT89EB5114"
1890:Atmel microcontrollers
1839:-related article is a
81:decoders and hardware
69:(two wire interface),
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1845:expanding it
1830:
1807:13 September
1805:. Retrieved
1801:
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1780:. Retrieved
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1752:. Retrieved
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