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PIC18F8620-I/PT 参数 Datasheet PDF下载

PIC18F8620-I/PT图片预览
型号: PIC18F8620-I/PT
PDF下载: 下载PDF文件 查看货源
内容描述: 八十〇分之六十四引脚高性能1 Mbit的增强型闪存微控制器与A / D [64/80-Pin High Performance 1 Mbit Enhanced FLASH Microcontrollers with A/D]
分类和应用: 闪存微控制器和处理器外围集成电路PC时钟
文件页数/大小: 366 页 / 6797 K
品牌: MICROCHIP [ MICROCHIP ]
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PIC18FXX20  
reloaded and begins counting. If SDA goes from high to  
low before the BRG times out, no bus collision occurs  
because no two masters can assert SDA at exactly the  
same time.  
If SCL goes from high to low before the BRG times out  
and SDA has not already been asserted, a bus collision  
occurs. In this case, another master is attempting to  
transmit a data ’1’ during the Repeated START  
condition, Figure 17-30.  
If, at the end of the BRG time-out, both SCL and SDA  
are still high, the SDA pin is driven low and the BRG is  
reloaded and begins counting. At the end of the count,  
regardless of the status of the SCL pin, the SCL pin is  
driven low and the Repeated START condition is  
complete.  
17.4.17.2 Bus Collision During a Repeated  
START Condition  
During a Repeated START condition, a bus collision  
occurs if:  
a) A low level is sampled on SDA when SCL goes  
from low level to high level.  
b) SCL goes low before SDA is asserted low, indi-  
cating that another master is attempting to  
transmit a data ’1’.  
When the user de-asserts SDA and the pin is allowed to  
float high, the BRG is loaded with SSPADD<6:0> and  
counts down to ‘0’. The SCL pin is then de-asserted,  
and when sampled high, the SDA pin is sampled.  
If SDA is low, a bus collision has occurred (i.e., another  
master is attempting to transmit  
a
data ’0’,  
Figure 17-29). If SDA is sampled high, the BRG is  
FIGURE 17-29:  
BUS COLLISION DURING A REPEATED START CONDITION (CASE 1)  
SDA  
SCL  
Sample SDA when SCL goes high.  
If SDA = 0, set BCLIF and release SDA and SCL.  
RSEN  
BCLIF  
Cleared in software  
'0'  
S
'0'  
SSPIF  
FIGURE 17-30:  
BUS COLLISION DURING REPEATED START CONDITION (CASE 2)  
TBRG  
TBRG  
SDA  
SCL  
SCL goes low before SDA,  
BCLIF  
RSEN  
Set BCLIF. Release SDA and SCL.  
Interrupt cleared  
in software  
'0'  
S
SSPIF  
DS39609A-page 194  
Advance Information  
2003 Microchip Technology Inc.  
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