Datasheet 搜索 > 微控制器 > ATMEL（爱特美尔） > AT89LP52-20JU 数据手册 > AT89LP52-20JU 数据手册 12/118 页
器件3D模型￥ 10.565
AT89LP52-20JU 数据手册 - ATMEL（爱特美尔）
制造商:
ATMEL（爱特美尔）
分类:
微控制器
封装:
PLCC-44
Pictures:
3D模型
符号图
焊盘图
引脚图
产品图
页面导航:
导航目录
AT89LP52-20JU数据手册
Page:
of 118 Go
若手册格式错乱，请下载阅览PDF原文件
12
3709D–MICRO–12/11
AT89LP51/52
Figure 3-1. Program Memory Map
3.1.1 External Program Memory Interface
The AT89LP51/52 uses the standard 8051 external program memory interface with the upper
address on Port 2, the lower address and data in/out multiplexed on Port 0, and the ALE and
PSEN
strobes. Program memory addresses are always 16-bits wide, even though the actual
amount of program memory used may be less than 64K byes. External program execution sacri-
fices two full 8-bit ports, P0 and P2, to the function of addressing the program memory.
Figure 3-2 shows a hardware configuration for a
ccessing up to 64K bytes of external ROM using
a 16-bit linear address. Port 0 serves as a multiplexed address/data bus to the ROM. The
Address Latch Enable strobe (ALE) is used to latch the lower address byte into an external reg-
ister so that Port 0 can b e freed for data inpu t/output. Port 2 provides the upper address byte
throughou t the operation. PSEN strobes the external memory.
Figure 3-3 shows the timing of the external program memory interface. ALE is emitted at a con-
stant rate of 1/3 of the system clock with a 1/3 duty cycle. PSEN
is emitted at a similar rate, but
with 50% duty cycle. The new address changes in the middle of the ALE pulse for latching on
the falling edge and is tristated at the falling edge of PSEN
. The instruction data is sampled from
P0 and latched internally during the high phase of the clock prior to the rising edge of PSEN
.
This timing applies to both Compatibility a nd Fast modes. In Compatibility mode there is no dif-
ference in instruction timing between internal and external execution.
Figure 3-2. Executing from External Program Memory
0000
FFFF
0000
007F
User Signature Array
0100
01FF
Atmel Signature Array
SIGEN=0
SIGEN=1
AT89LP52
2000
1FFF
External Program
Memory
(XCODE: 56KB)
Internal Program
Memory
(CODE: 8KB)
0000
FFFF
0000
007F
User Signature Array
0100
01FF
Atmel Signature Array
AT89LP51
1000
0FFF
External Program
Memory
(XCODE: 60KB)
Internal Program
Memory
(CODE: 4KB)
AT89LP EXTERNAL
PROGRAM
MEMORY
INSTR.
ADDR
OEPSEN
P3
P2
ALE
P0P1
LATCH
器件 Datasheet 文档搜索
AiEMA 数据库涵盖高达 72,405,303 个元件的数据手册，每天更新 5,000 多个 PDF 文件
