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68HC705JJ7_1 参数 Datasheet PDF下载

68HC705JJ7_1图片预览
型号: 68HC705JJ7_1
PDF下载: 下载PDF文件 查看货源
内容描述: 常规版本规格 [General Release Specification]
分类和应用:
文件页数/大小: 230 页 / 5548 K
品牌: FREESCALE [ Freescale ]
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Freescale Semiconductor, Inc.  
Parallel Input/Output  
Port A  
7.3.3 Pulld own Re g iste r A (PDRA)  
All port A pins can have software programmable pulldown devices  
enabled or disabled globally by SWPDI bit in the MOR. These pulldown  
devices are controlled by the write-only pulldown register A (PDRA)  
shown in Figure 7-3. Clearing the PDIA5–PDIA0 bits in the PDRA turns  
on the pulldown devices if the port A pin is an input. Reading the PDRA  
returns undefined results since it is a write-only register, therefore do not  
change the value in PDRA with read/modify/write instructions. On the  
MC68HC705JP7 the PDRA contains two pulldown control bits (PDICH  
and PDICL) for port C. Reset clears the PDIA5–PDIA0, PDICH and  
PDICL bits, which turns on all the port A and port C pulldown devices.  
$0010  
Read:  
Bit 7  
6
5
4
3
2
1
Bit 0  
Write: PDICH  
Reset:  
PDICL  
0
PDIA5  
0
PDIA4  
0
PDIA3  
0
PDIA2  
0
PDIA1  
0
PDIA0  
0
0
= Unimplemented  
Figure 7-3. Pulldown Register A (PDRA)  
PDICH — Upper Port C Pulldown Inhibit Bits (MC68HC705JP7)  
Writing to this write-only bit controls the port C pulldown devices on  
the upper four bits (PC4:7). Reading these pulldown register A bits  
returns undefined data. Reset clears bit PDICH.  
1 = Upper four port C pins pulldown devices turned off  
0 = Upper four port C pins pulldown devices turned on if pin has  
been programmed by the DDRC to be an input  
PDICL — Lower Port C Pulldown Inhibit Bits (MC68HC705JP7)  
Writing to this write-only bit controls the port C pulldown devices on  
the lower four bits (PC0:3). Reading these pulldown register A bits  
returns undefined data. Reset clears bit PDICL.  
1 = Lower four port C pins pulldown devices turned off  
0 = Lower four port C pins pulldown devices turned on if pin has  
been programmed by the DDRC to be an input  
MC68HC705JJ7/MC68HC705JP7 Rev. 3.0  
General Release Specification  
Parallel Input/Output  
For More Information On This Product,  
Go to: www.freescale.com  
 
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