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PIC16F877T-20PQ 参数 Datasheet PDF下载

PIC16F877T-20PQ图片预览
型号: PIC16F877T-20PQ
PDF下载: 下载PDF文件 查看货源
内容描述: 8位微控制器\n [8-Bit Microcontroller ]
分类和应用: 微控制器
文件页数/大小: 200 页 / 3338 K
品牌: ETC [ ETC ]
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PIC16F87X  
2
9.2.9  
I C MASTER MODE START CONDITION  
TIMING  
Note: If at the beginning of START condition the  
SDA and SCL pins are already sampled  
low, or if during the START condition the  
SCL line is sampled low before the SDA  
line is driven low, a bus collision occurs, the  
Bus Collision Interrupt Flag (BCLIF) is set,  
the START condition is aborted, and the  
To initiate a START condition, the user sets the start  
condition enable bit, SEN (SSPCON2<0>). If the SDA  
and SCL pins are sampled high, the baud rate genera-  
tor is re-loaded with the contents of SSPADD<6:0> and  
starts its count. If SCL and SDA are both sampled high  
when the baud rate generator times out (TBRG), the  
SDA pin is driven low. The action of the SDA being  
driven low while SCL is high is the START condition,  
and causes the S bit (SSPSTAT<3>) to be set. Follow-  
ing this, the baud rate generator is reloaded with the  
contents of SSPADD<6:0> and resumes its count.  
When the baud rate generator times out (TBRG), the  
SEN bit (SSPCON2<0>) will be automatically cleared  
by hardware. The baud rate generator is suspended  
leaving the SDA line held low, and the START condition  
is complete.  
2
I C module is reset into its IDLE state.  
9.2.9.1  
WCOL STATUS FLAG  
If the user writes the SSPBUF when an START  
sequence is in progress, then WCOL is set and the  
contents of the buffer are unchanged (the write doesn’t  
occur).  
Note: Because queueing of events is not  
allowed, writing to the lower 5 bits of  
SSPCON2 is disabled until the START  
condition is complete.  
FIGURE 9-12: FIRST START BIT TIMING  
Set S bit (SSPSTAT<3>)  
Write to SEN bit occurs here.  
SDA = 1,  
At completion of start bit,  
Hardware clears SEN bit  
and sets SSPIF bit  
SCL = 1  
TBRG  
TBRG  
Write to SSPBUF occurs here  
1st Bit 2nd Bit  
SDA  
TBRG  
SCL  
TBRG  
S
1999 Microchip Technology Inc.  
DS30292B-page 79  
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