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参数资料
| 型号： | PIC18F2321-E/SP |
| 厂商： | Microchip Technology |
| 文件页数： | 73/110页 |
| 文件大小： | 0K |
| 描述： | IC PIC MCU FLASH 4KX16 28SPDIP |
| 产品培训模块： | Asynchronous Stimulus |
| 标准包装： | 15 |
| 系列： | PIC® 18F |
| 核心处理器： | PIC |
| 芯体尺寸： | 8-位 |
| 速度： | 25MHz |
| 连通性： | I²C，SPI，UART/USART |
| 外围设备： | 欠压检测/复位，HLVD，POR，PWM，WDT |
| 输入/输出数： | 25 |
| 程序存储器容量： | 8KB（4K x 16） |
| 程序存储器类型： | 闪存 |
| EEPROM 大小： | 256 x 8 |
| RAM 容量： | 512 x 8 |
| 电压 - 电源 (Vcc/Vdd)： | 4.2 V ~ 5.5 V |
| 数据转换器： | A/D 10x10b |
| 振荡器型： | 内部 |
| 工作温度： | -40°C ~ 125°C |
| 封装/外壳： | 28-DIP（0.300"，7.62mm） |
| 包装： | 管件 |
| 配用： | DVA18XP280-ND - DEVICE ADAPTER 18F2220 PDIP 28LD |
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2009 Microchip Technology Inc.
DS39689F-page 65
PIC18F2221/2321/4221/4321 FAMILY
6.3
Data Memory Organization
The data memory in PIC18 devices is implemented as
static RAM. Each register in the data memory has a
12-bit address, allowing up to 4096 bytes of data
memory. The memory space is divided into as many as
16 banks that contain 256 bytes each; PIC18F2221/
2321/4221/4321 family devices implement 2 banks.
Figure 6-5 shows the data memory organization for the
PIC18F2221/2321/4221/4321 family devices.
The data memory contains Special Function Registers
(SFRs) and General Purpose Registers (GPRs). The
SFRs are used for control and status of the controller
and peripheral functions, while GPRs are used for data
storage and scratchpad operations in the user’s
application. Any read of an unimplemented location will
read as ‘0’s.
The instruction set and architecture allow operations
across all banks. The entire data memory may be
accessed by Direct, Indirect or Indexed Addressing
modes. Addressing modes are discussed later in this
subsection.
To ensure that commonly used registers (SFRs and
select GPRs) can be accessed in a single cycle, PIC18
devices implement an Access Bank. This is a 256-byte
memory space that provides fast access to SFRs and
the lower portion of GPR Bank 0 without using the
BSR. Section 6.3.2 “Access Bank” provides a
detailed description of the Access RAM.
6.3.1
BANK SELECT REGISTER (BSR)
Large areas of data memory require an efficient
addressing scheme to make rapid access to any
address possible. Ideally, this means that an entire
address does not need to be provided for each read or
write operation. For PIC18 devices, this is accomplished
with a RAM banking scheme. This divides the memory
space into 16 contiguous banks of 256 bytes. Depend-
ing on the instruction, each location can be addressed
directly by its full 12-bit address, or an 8-bit low-order
address and a 4-bit Bank Pointer.
Most instructions in the PIC18 instruction set make use
of the Bank Pointer, known as the Bank Select Register
(BSR). This SFR holds the four Most Significant bits of
a location’s address; the instruction itself includes the
8 Least Significant bits. Only the four lower bits of the
BSR are implemented (BSR3:BSR0). The upper four
bits are unused; they will always read ‘0’ and cannot be
written to. The BSR can be loaded directly by using the
MOVLB instruction.
The value of the BSR indicates the bank in data
memory; the 8 bits in the instruction show the location
in the bank and can be thought of as an offset from the
bank’s lower boundary. The relationship between the
BSR’s value and the bank division in data memory is
shown in Figure 6-6.
Since up to 16 registers may share the same low-order
address, the user must always be careful to ensure that
the proper bank is selected before performing a data
read or write. For example, writing what should be
program data to an 8-bit address of F9h, while the BSR
is 0Fh, will end up resetting the program counter.
While any bank can be selected, only those banks that
are actually implemented can be read or written to.
Writes to unimplemented banks are ignored, while
reads from unimplemented banks will return ‘0’s. Even
so, the STATUS register will still be affected as if the
operation was successful. The data memory map in
Figure 6-5 indicates which banks are implemented.
In the core PIC18 instruction set, only the MOVFF
instruction fully specifies the 12-bit address of the
source and target registers. This instruction ignores the
BSR completely when it executes. All other instructions
include only the low-order address as an operand and
must use either the BSR or the Access Bank to locate
their target registers.
Note:
The operation of some aspects of data
memory are changed when the PIC18
extended instruction set is enabled. See
Extended Instruction Set” for more
information.
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相关代理商/技术参数 |
参数描述 |
|---|---|
| PIC18F2321-I/ML | 功能描述:8位微控制器 -MCU 8 KB Flash 512 RAM 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 |
| PIC18F2321-I/SO | 功能描述:8位微控制器 -MCU 8 KB Flash 512 RAM 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 |
| PIC18F2321-I/SP | 功能描述:8位微控制器 -MCU 8 KB Flash 512 RAM 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 |
| PIC18F2321-I/SP | 制造商:Microchip Technology Inc 功能描述:8-Bit Microcontroller IC |
| PIC18F2321-I/SS | 功能描述:8位微控制器 -MCU 8KB Flash 512bytes 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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