参数资料
型号: AT89LP51-20PU
厂商: Atmel
文件页数: 55/117页
文件大小: 0K
描述: MCU 8051 4K FLASH 20MHZ
标准包装: 10
系列: 89LP
核心处理器: 8051
芯体尺寸: 8-位
速度: 20MHz
连通性: EBI/EMI,I²C,SPI,UART/USART
外围设备: 欠压检测/复位,POR,PWM,WDT
输入/输出数: 36
程序存储器容量: 4KB(4K x 8)
程序存储器类型: 闪存
RAM 容量: 256 x 8
电压 - 电源 (Vcc/Vdd): 2.4 V ~ 5.5 V
振荡器型: 内部
工作温度: -40°C ~ 85°C
封装/外壳: 40-DIP(0.600",15.24mm)
包装: 管件
42
3709D–MICRO–12/11
AT89LP51/52
.
10.1.1
Quasi-bidirectional Output
Port pins in quasi-bidirectional output mode function similar to standard 8051 port pins. A Quasi-
bidirectional port can be used both as 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 driven low, it is driven strongly and able to
sink a large current. There are three pull-up transistors in the quasi-bidirectional output that
serve different purposes.
One of these pull-ups, called the “very weak” pull-up, is turned on whenever the port latch for the
pin contains a logic “1”. This very weak pull-up sources a very small current that will pull the pin
high if it is left floating. When the pin is pulled low externally this pull-up will always source some
current.
A second pull-up, called the “weak” 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-bidirectional pin that is outputting a “1”. If this pin is pulled low by an external
device, this weak pull-up turns off, and only the very 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
weak pull-up and pull the port pin below its input threshold voltage.
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 one CPU clock, quickly pulling the port
pin high. The quasi-bidirectional port configuration is shown in Figure 10-1.
10.1.2
Input-only Mode
The input only port configuration is shown in Figure 10-2. The output drivers are tristated. The
input includes a Schmitt-triggered input for improved input noise rejection. The input circuitry of
P3.2, P3.3, P4.6 and P4.7 is not disabled during Power-down (see Figure 10-3) and therefore
these pins should not be left floating during Power-down when configured in this mode.
Input-only mode can reduce power consumption for low-level inputs over quasi-bidirectional
mode because the “very weak” pull-up is turned off and only very small leakage current in the
sub microamp range is present.
Table 10-3.
PMOD
– Port Mode Register
PMOD = C1H
Reset Value = 0000 0011B
Not Bit Addressable
P3M1
P3M0
P2M1
P2M0
P1M1
P1M0
P0M1
P0M0
Bit
7
6
543
21
0
Symbol
Function
P3M1-0
Port 3 Configuration Mode
P2M
1-0
Port 2 Configuration Mode
P1M1-0
Port 1 Configuration Mode
P0M1-0
Port 0 Configuration Mode
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AT89LP51ED2-20JU 功能描述:8位微控制器 -MCU 64KB 20MHz 2.4V-5.5V RoHS:否 制造商:Silicon Labs 核心:8051 处理器系列:C8051F39x 数据总线宽度:8 bit 最大时钟频率:50 MHz 程序存储器大小:16 KB 数据 RAM 大小:1 KB 片上 ADC:Yes 工作电源电压:1.8 V to 3.6 V 工作温度范围:- 40 C to + 105 C 封装 / 箱体:QFN-20 安装风格:SMD/SMT
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