24
AT89C51RB2/RC2
4180E–8051–10/06
Instructions that use indirect addressing access the Upper 128 Bytes of data RAM.
For example: MOV @R0, # data where R0 contains 0A0h, accesses the data Byte
at address 0A0h, rather than P2 (whose address is 0A0h).
The XRAM Bytes can be accessed by indirect addressing, with EXTRAM bit cleared
and MOVX instructions. This part of memory that is physically located on-chip,
logically occupies the first Bytes of external data memory. The bits XRS0 and XRS1
are used to hide a part of the available XRAM as explained in Table 18. This can be
useful if external peripherals are mapped at addresses already used by the internal
XRAM.
With EXTRAM = 0, the XRAM is indirectly addressed, using the MOVX instruction in
combination with any of the registers R0, R1 of the selected bank or DPTR. An
access to XRAM will not affect ports P0, P2, P3.6 (WR) and P3.7 (RD). For
example, with EXTRAM = 0, MOVX @R0, # data where R0 contains 0A0H,
accesses the XRAM at address 0A0H rather than external memory. An access to
external data memory locations higher than the accessible size of the XRAM will be
performed with the MOVX DPTR instructions in the same way as in the standard
80C51, with P0 and P2 as data/address busses, and P3.6 and P3.7 as write and
read timing signals. Accesses to XRAM above 0FFH can only be done by the use of
DPTR.
With EXTRAM = 1, MOVX @RI and MOVX @DPTR will be similar to the standard
80C51. MOVX @ Ri will provide an eight-bit address multiplexed with data on Port0
and any output port pins can be used to output higher order address bits. This is to
provide the external paging capability. MOVX @DPTR will generate a sixteen-bit
address. Port2 outputs the high-order eight address bits (the contents of DPH) while
Port0 multiplexes the low-order eight address bits (DPL) with data. MOVX @ RI and
MOVX @DPTR will generate either read or write signals on P3.6 (WR) and P3.7
(RD).
The stack pointer (SP) may be located anywhere in the 256 Bytes RAM (lower and
upper RAM) internal data memory. The stack may not be located in the XRAM.
The M0 bit allows to stretch the XRAM timings; if M0 is set, the read and write pulses
are extended from 6 to 30 clock periods. This is useful to access external slow
peripherals.
相关PDF资料
PIC16C72A-04/SO IC MCU OTP 2KX14 A/D PWM 28SOIC
AT89C51ID2-RLTIM IC 8051 MCU FLASH 64K 44VQFP
AT89C51IC2-SLSIL IC 8051 MCU FLASH 32K 44PLCC
AT89C51CC03U-RLTIM IC 8051 MCU FLASH 64K 44VQFP
PIC24EP64MC204-I/PT MCU 16BIT 64KB FLASH 44TQFP
AT89C51CC03U-RDTIM IC 8051 MCU FLASH 64K 64VQFP
AT89C51CC03U-7CTIM IC 8051 MCU FLASH 64K 64BGA
AT89C51CC03C-S3SIM IC 8051 MCU FLASH 64K 52PLCC
相关代理商/技术参数
AT89C51RB2-3CSUL 功能描述:8位微控制器 -MCU 8-bit 16K Flash C51RB2 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
AT89C51RB2-3CSUM 功能描述:8位微控制器 -MCU C51RB2 FLASH 5V 16k ind 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
AT89C51RB2L1-RLTUL 功能描述:8位微控制器 -MCU Microcontroller 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
AT89C51RB2-RLRIL 功能描述:IC MCU FLASH 8051 16K 3V 44-VQFP RoHS:否 类别:集成电路 (IC) >> 嵌入式 - 微控制器, 系列:89C 标准包装:1,500 系列:AVR® ATtiny 核心处理器:AVR 芯体尺寸:8-位 速度:16MHz 连通性:I²C,LIN,SPI,UART/USART,USI 外围设备:欠压检测/复位,POR,PWM,温度传感器,WDT 输入/输出数:16 程序存储器容量:8KB(4K x 16) 程序存储器类型:闪存 EEPROM 大小:512 x 8 RAM 容量:512 x 8 电压 - 电源 (Vcc/Vdd):2.7 V ~ 5.5 V 数据转换器:A/D 11x10b 振荡器型:内部 工作温度:-40°C ~ 125°C 封装/外壳:20-SOIC(0.295",7.50mm 宽) 包装:带卷 (TR)
AT89C51RB2-RLRIM 功能描述:IC MCU FLASH 8051 16K 5V 44-VQFP RoHS:否 类别:集成电路 (IC) >> 嵌入式 - 微控制器, 系列:89C 产品培训模块:MCU Product Line Introduction AVR® UC3 Introduction 标准包装:2,500 系列:AVR®32 UC3 B 核心处理器:AVR 芯体尺寸:32-位 速度:60MHz 连通性:I²C,IrDA,SPI,SSC,UART/USART,USB 外围设备:欠压检测/复位,DMA,POR,PWM,WDT 输入/输出数:28 程序存储器容量:128KB(128K x 8) 程序存储器类型:闪存 EEPROM 大小:- RAM 容量:32K x 8 电压 - 电源 (Vcc/Vdd):1.65 V ~ 1.95 V 数据转换器:A/D 6x10b 振荡器型:内部 工作温度:-40°C ~ 85°C 封装/外壳:48-TQFP 包装:带卷 (TR) 配用:ATSTK600-TQFP48-ND - STK600 SOCKET/ADAPTER 48-TQFPATAVRONEKIT-ND - KIT AVR/AVR32 DEBUGGER/PROGRMMRATEVK1101-ND - KIT DEV/EVAL FOR AVR32 AT32UC3B 其它名称:AT32UC3B1128-AUR-NDAT32UC3B1128-AURTR
AT89C51RB2-RLRUL 功能描述:8位微控制器 -MCU C51RB2 FLASH 3V 16k ind 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
AT89C51RB2-RLRUM 功能描述:8位微控制器 -MCU C51RB2 FLASH 5V 16k ind 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
AT89C51RB2-RLTCM 制造商:ATMEL 制造商全称:ATMEL Corporation 功能描述:8-bit Microcontroller with 16K/ 32K Bytes Flash