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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.  
Pa ra lle l Inp ut/ Outp ut  
7.5.2 Da ta Dire c tion Re g iste r C (DDRC)  
The contents of the port C data direction register (DDRC) determine  
whether each port C pin is an input or an output. Writing a logic one to a  
DDRC bit enables the output buffer for the associated port C pin. A  
DDRC bit set to a logic one also disables the pulldown device for that pin.  
Writing a logic zero to a DDRC bit disables the output buffer for the  
associated port C pin. A reset initializes all DDRC bits to logic zeros,  
configuring all port C pins as inputs.  
$0006  
Read:  
Write:  
Reset:  
Bit 7  
6
5
4
3
2
1
Bit 0  
DDRC7 DDRC6 DDRC5 DDRC4 DDRC3 DDRC2 DDRC1 DDRC0  
0
0
0
0
0
0
0
0
= Unimplemented  
Figure 7-14. Data Direction Register C (DDRC)  
DDRC7–DDRC0 — Port C Data Direction Bits  
These read/write bits control port C data direction. Reset clears the  
DDRC7–DDRC0 bits.  
1 = Corresponding port C pin configured as output and pulldown  
device disabled  
0 = Corresponding port C pin configured as input  
7.5.3 Port C Pulld own De vic e s  
All port C pins can have software programmable pulldown devices  
enabled or disabled globally by the SWPDI bit in the MOR. These  
pulldown devices are individually controlled by the write-only pulldown  
register A (PDRA) shown in Figure 7-3. PDICH controls the upper four  
pins (PC7:4) and PDICL controls the lower four pins (PC3:0). Clearing  
the PDICH or PDICL bits in the PDRA turns on the pulldown devices if  
the port C pin is an input. Reading the PDRA returns undefined results  
since it is a write-only register. Reset clears the PDICH and PDICL bits,  
which turns on all the port C pulldown devices.  
General Release Specification  
MC68HC705JJ7/MC68HC705JP7 Rev. 3.0  
Parallel Input/Output  
For More Information On This Product,  
Go to: www.freescale.com  
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