參數(shù)資料
型號： AT89C51ED2-SMSUM
廠商： Atmel
文件頁數(shù)： 44/137頁
文件大?。?/td> 0K
描述： IC 8051 MCU FLASH 64K 68PLCC
產(chǎn)品培訓模塊： MCU Product Line Introduction
標準包裝： 304
系列： 89C
核心處理器： 8051
芯體尺寸： 8-位
速度： 60MHz
連通性： SPI，UART/USART
外圍設(shè)備： POR，PWM，WDT
輸入/輸出數(shù)： 50
程序存儲器容量： 64KB（64K x 8）
程序存儲器類型： 閃存
EEPROM 大?。?/td> 2K x 8
RAM 容量： 2K x 8
電壓 - 電源 (Vcc/Vdd)： 2.7 V ~ 5.5 V
振蕩器型： 外部
工作溫度： -40°C ~ 85°C
封裝/外殼： 68-PLCC
包裝： 管件
配用： AT89OCD-01-ND - USB EMULATOR FOR AT8XC51 MCU
14
4235K–8051–05/08
AT89C51RD2/ED2
5.
Port Types
AT89C51RD2/ED2 I/O ports (P1, P2, P3, P4, P5) implement the quasi-bidirectional output that
is common on the 80C51 and most of its derivatives. This output type can be used as both an
input and output without the need to reconfigure the port. This is possible because when the port
outputs a logic high, it is weakly driven, allowing an external device to pull the pin low. When the
pin is pulled low, it is driven strongly and able to sink a fairly large current. These features are
somewhat similar to an open drain output except that there are three pull-up transistors in the
quasi-bidirectional output that serve different purposes. One of these pull-ups, called the "weak"
pull-up, is turned on whenever the port latch for the pin contains a logic 1. The weak pull-up
sources a very small current that will pull the pin high if it is left floating. A second pull-up, called
the "medium" pull-up, is turned on when the port latch for the pin contains a logic 1 and the pin
itself is also at a logic 1 level. This pull-up provides the primary source current for a quasi-bidi-
rectional pin that is outputting a 1. If a pin that has a logic 1 on it is pulled low by an external
device, the medium pull-up turns off, and only the weak pull-up remains on. In order to pull the
pin low under these conditions, the external device has to sink enough current to overpower the
medium pull-up and take the voltage on the port pin below its input threshold.
The third pull-up is referred to as the "strong" pull-up. This pull-up is used to speed up low-to-
high transitions on a quasi-bidirectional port pin when the port latch changes from a logic 0 to a
logic 1. When this occurs, the strong pull-up turns on for a brief time, two CPU clocks, in order to
pull the port pin high quickly. Then it turns off again.
The DPU bit (bit 7 in AUXR register) allows to disable the permanent weak pull up of all ports
when latch data is logical 0.
The quasi-bidirectional port configuration is shown in Figure 5-1.
Figure 5-1.
Quasi-Bidirectional Output
2 CPU
Input
Pin
Strong
Medium
N
Weak
P
Clock Delay
Port Latch
Data
DPU
AUXR.7
P
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參數(shù)描述
AT89C51ED2-UM 制造商:ATMEL 制造商全稱:ATMEL Corporation 功能描述:8-bit Flash Microcontroller
AT89C51IC2 制造商:ATMEL 制造商全稱:ATMEL Corporation 功能描述:8-bit Flash Microcontroller with 2-wire Interface
AT89C51IC2_04 制造商:ATMEL 制造商全稱:ATMEL Corporation 功能描述:8-bit Flash Microcontroller with 2-wire Interface
AT89C51IC2_08 制造商:ATMEL 制造商全稱:ATMEL Corporation 功能描述:8-bit Flash Microcontroller with 2-wire Interface
AT89C51IC2-RLRIL 功能描述:IC MCU FLASH 8051 32K 3V 44-VQFP RoHS:否 類別:集成電路 (IC) >> 嵌入式 - 微控制器， 系列:89C 標準包裝:1 系列:AVR® ATmega 核心處理器:AVR 芯體尺寸:8-位 速度:16MHz 連通性:I²C，SPI，UART/USART 外圍設(shè)備:欠壓檢測/復(fù)位，POR，PWM，WDT 輸入/輸出數(shù):32 程序存儲器容量:32KB（16K x 16） 程序存儲器類型:閃存 EEPROM 大小:1K x 8 RAM 容量:2K x 8 電壓 - 電源 (Vcc/Vdd):2.7 V ~ 5.5 V 數(shù)據(jù)轉(zhuǎn)換器:A/D 8x10b 振蕩器型:內(nèi)部 工作溫度:-40°C ~ 125°C 封裝/外殼:44-TQFP 包裝:剪切帶 (CT) 其它名稱:ATMEGA324P-B15AZCT
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