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参数资料
型号： PIC16F871T-E/L
厂商： Microchip Technology
文件页数： 63/143页
文件大小： 0K
描述： IC MCU CMOS 20MHZ 2K FLSH 44PLCC
标准包装： 500
系列： PIC® 16F
核心处理器： PIC
芯体尺寸： 8-位
速度： 20MHz
连通性： UART/USART
外围设备： 欠压检测/复位，POR，PWM，WDT
输入/输出数： 33
程序存储器容量： 3.5KB（2K x 14）
程序存储器类型： 闪存
EEPROM 大小： 64 x 8
RAM 容量： 128 x 8
电压 - 电源 (Vcc/Vdd)： 4 V ~ 5.5 V
数据转换器： A/D 8x10b
振荡器型： 外部
工作温度： -40°C ~ 125°C
封装/外壳： 44-LCC（J 形引线）
包装： 带卷 (TR)
PIC16F870/871
DS30569B-page 24
2003 Microchip Technology Inc.
2.3
PCL and PCLATH
The Program Counter (PC) is 13-bits wide. The low
byte comes from the PCL register, which is a readable
and writable register. The upper bits (PC<12:8>) are
not readable, but are indirectly writable through the
PCLATH register. On any RESET, the upper bits of the
PC will be cleared. Figure 2-3 shows the two situations
for the loading of the PC. The upper example in the fig-
ure shows how the PC is loaded on a write to PCL
(PCLATH<4:0>
→ PCH). The lower example in the fig-
ure shows how the PC is loaded during a CALL or GOTO
instruction (PCLATH<4:3>
→ PCH).
FIGURE 2-3:
LOADING OF PC IN
DIFFERENT SITUATIONS
2.3.1
COMPUTED GOTO
A computed GOTO is accomplished by adding an offset
to the program counter (ADDWF PCL). When doing a
table read using a computed GOTO method, care
should be exercised if the table location crosses a PCL
memory boundary (each 256-byte block). Refer to the
application
note,
“Implementing
a
Table
Read"
(AN556).
2.3.2
STACK
The PIC16FXXX family has an 8-level deep x 13-bit
wide hardware stack. The stack space is not part of
either program or data space and the stack pointer is
not readable or writable. The PC is PUSHed onto the
stack when a CALL instruction is executed, or an inter-
rupt causes a branch. The stack is POPed in the event
of a RETURN, RETLW or a RETFIE instruction
execution. PCLATH is not affected by a PUSH or POP
operation.
The stack operates as a circular buffer. This means that
after the stack has been PUSHed eight times, the ninth
push overwrites the value that was stored from the first
push. The tenth push overwrites the second push (and
so on).
2.4
Program Memory Paging
The PIC16FXXX architecture is capable of addressing
a continuous 8K word block of program memory. The
CALL
and GOTO instructions provide 11 bits of the
address, which allows branches within any 2K program
memory page. Therefore, the 8K words of program
memory are broken into four pages. Since the
PIC16F872 has only 2K words of program memory or
one page, additional code is not required to ensure that
the correct page is selected before a CALL or GOTO
instruction is executed. The PCLATH<4:3> bits should
always be maintained as zeros. If a return from a CALL
instruction (or interrupt) is executed, the entire 13-bit
PC is popped off the stack. Manipulation of the
PCLATH is not required for the return instructions.
2.5
Indirect Addressing, INDF and
FSR Registers
The INDF register is not a physical register. Addressing
the INDF register will cause indirect addressing.
Indirect addressing is possible by using the INDF reg-
ister. Any instruction using the INDF register actually
accesses the register pointed to by the File Select reg-
ister, FSR. Reading the INDF register itself indirectly
(FSR = 0) will read 00h. Writing to the INDF register
indirectly results in a no operation (although status bits
may be affected). An effective 9-bit address is obtained
by concatenating the 8-bit FSR register and the IRP bit
(STATUS<7>), as shown in Figure 2-4.
A simple program to clear RAM locations 20h-2Fh
using indirect addressing is shown in Example 2-1.
EXAMPLE 2-1:
INDIRECT ADDRESSING
PC
12
8
7
0
5
PCLATH<4:0>
PCLATH
Instruction with
ALU
GOTO,CALL
Opcode <10:0>
8
PC
12
11 10
0
11
PCLATH<4:3>
PCH
PCL
87
2
PCLATH
PCH
PCL
PCL as
Destination
Note 1: There are no status bits to indicate stack
overflow or stack underflow conditions.
2: There are no instructions/mnemonics
called PUSH or POP. These are actions
that occur from the execution of the CALL,
RETURN
, RETLW and RETFIE instruc-
tions, or the vectoring to an interrupt
address.
movlw
0x20
;initialize pointer
movwf
FSR
;to RAM
NEXT
clrf
INDF
;clear INDF register
incf
FSR,F
;inc pointer
btfss
FSR,4
;all done?
goto
NEXT
;no clear next
CONTINUE
:
;yes continue
相关PDF资料
PDF描述
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相关代理商/技术参数
参数描述
PIC16F871T-I/L 功能描述:8位微控制器 -MCU 3.5KB 128 RAM 33 I/O 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
PIC16F871T-I/PT 功能描述:8位微控制器 -MCU 3.5KB 128 RAM 33 I/O 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
PIC16F872-E/SO 功能描述:8位微控制器 -MCU 3.5KB 128 RAM 22 I/O 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
PIC16F872-E/SOVAO 制造商:Microchip Technology Inc 功能描述:
PIC16F872-E/SP 功能描述:8位微控制器 -MCU 3.5KB 128 RAM 22 I/O 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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