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PIC16F877T-20IL301 参数 Datasheet PDF下载

PIC16F877T-20IL301图片预览
型号: PIC16F877T-20IL301
PDF下载: 下载PDF文件 查看货源
内容描述: 微控制器\n [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  
9.1.1  
MASTER MODE  
Figure 9-6, Figure 9-8 and Figure 9-9 where the MSb is  
transmitted first. In master mode, the SPI clock rate (bit  
rate) is user programmable to be one of the following:  
The master can initiate the data transfer at any time  
because it controls the SCK. The master determines  
when the slave (Processor 2, Figure 9-5) is to broad-  
cast data by the software protocol.  
• FOSC/4 (or TCY)  
• FOSC/16 (or 4 • TCY)  
• FOSC/64 (or 16 • TCY)  
• Timer2 output/2  
In master mode, the data is transmitted/received as  
soon as the SSPBUF register is written to. If the SPI  
module is only going to receive, the SDO output could  
be disabled (programmed as an input). The SSPSR  
register will continue to shift in the signal present on the  
SDI pin at the programmed clock rate. As each byte is  
received, it will be loaded into the SSPBUF register as  
if a normal received byte (interrupts and status bits  
appropriately set). This could be useful in receiver  
applications as a “line activity monitor”.  
This allows a maximum bit clock frequency (at 20 MHz)  
of 5.0 MHz.  
Figure 9-6 shows the waveforms for Master mode.  
When CKE = 1, the SDO data is valid before there is a  
clock edge on SCK. The change of the input sample is  
shown based on the state of the SMP bit. The time  
when the SSPBUF is loaded with the received data is  
shown.  
The clock polarity is selected by appropriately program-  
ming bit CKP (SSPCON<4>). This then would give  
waveforms for SPI communication as shown in  
FIGURE 9-2: SPI MODE TIMING, MASTER MODE  
SCK (CKP = 0,  
CKE = 0)  
SCK (CKP = 0,  
CKE = 1)  
SCK (CKP = 1,  
CKE = 0)  
SCK (CKP = 1,  
CKE = 1)  
bit2  
bit7  
bit6  
bit5  
bit3  
bit1  
bit0  
bit4  
SDO  
SDI (SMP = 0)  
bit7  
bit0  
SDI (SMP = 1)  
SSPIF  
bit7  
bit0  
DS30292B-page 68  
1999 Microchip Technology Inc.