SPI丢失MSb

您好，我使用的PIC18F23 K22似乎是由一个时钟周期过度移位的数据由SPI主机发送。我已经将一个逻辑分析器连接到SPI总线，并确认在SPI模式下的FT232H在时钟的下降沿上正确地发送数据，并且正确地对SPI总线计时一个字节的适当次数。从我观察到的SPI大师没有任何额外的时钟转换。我在时钟线上安装了示波器，我也没有在时钟线上发现任何毛病。为了帮助解决高速故障的可能性，我在时钟总线上安装了一个内线电阻，它也起到了阻尼边缘振铃的良好效果。然而，作为PIC18F23 K22的SPI从机左移所有接收比特1。如果0x46被发送到从站，从站保存0x8C，如果0x8C被发送，从站保存0x0C，最后如果0x1F被发送，从站保存0x3F。我试过同一系列的不同芯片，但问题是一致的。我已经没有办法解决这个问题了。有什么想法吗？非常感谢。-PIC18F23k22PLLCFG=OFF，PRICLKEN=ON，FCMEN=ON，FCMEN=OFF，IESO=OFF，FOSC=IESO=OFF，FOSC=HSMPBORE=OFF，IESO=OFOFOFOFOFF，IESO=OFOFF=OFF，BORV=220，PWRTEN=ONWRTEN=ONWWWRTEN=ONWWDTEN=OFFOFOFOFOFOFOFOFOFOFOFOFOFOFOFOFOFOFOFOFOFOFOFOFOFOFOFOFOFOFOFOFOFOFOFOFOFOFOFOFOFOFOFOFOFOFOFOFOFOFOFOFOFOFOFOFOFOFOFOFOFOFOFOFOFOFOFOFOFOFOFOFOFOFOFOF描述：SPI主机-FT232H bre从Ada.itSPI从属中退出-启用了PIC18F23K22 w/~CS。时钟极性-空闲低，有源高时钟速度-500KHz/2us周期数据输出-MSSP初始化代码段的上升边码配置



      以下为原文

    Hello,

The PIC18F23K22 I am using appears to be over-shifting by one clock cycle the data being transmitted by the SPI master. I have attached a logic analyzer to the SPI bus and confirmed that my FT232H in SPI mode is correctly sending data on the falling edge of the clock and is correctly clocking the SPI bus the proper amount of times for one byte. There isn't any extra clock transitions from the SPI Master that I have observed. I attached an oscilloscope to the clock line and I didn't observe any glitches on the clock line either. To help with the possibility of high speed glitches I put an inline resistor on my clock bus, it also had a nice affect of damping the edge ringing. However, the SPI Slave which is a PIC18F23K22 is left shifting all received bits by 1. If 0x46 is sent to the slave, the slave saves it 0x8C, if 0x8C is sent the slave saves 0x0C and finally if 0x1F is sent the slave saves 0x3F. The SPI clock speed is 500KHz and I do not think that my breadboard contributes enough noise to be a factor in this issue. I tried a different chip of the same series and the problem is consistent.
I have run out of ideas on how to resolve this problem.

Any ideas? Much Thanks.
-R

The configuration of the PIC18F23k22
PLLCFG=OFF, PRICLKEN=ON, FCMEN=OFF, IESO=OFF, FOSC=HSMP
BOREN=OFF, BORV=220, PWRTEN=ON
WDTPS=16384, WDTEN=OFF
HFOFST=OFF, PBADEN=OFF, MCLRE=EXTMCLR
STVREN=OFF, DEBUG=OFF, LVP=ON, XINST=OFF
Fosc = 11.0592MHz

Summary of Configuration:
SPI Master - FT232H breakout from AdaFruit
SPI Slave - PIC18F23K22 w/ ~CS enabled.
Clock Polarity - Idle Low, Active High
Clock Speed - 500KHz / 2 us period
Data Out - Falling Edge
Data In - Rising Edge
Code Config of the MSSP

MSSP Initialization Code snip
SSP1CON1bits.SSPM = 0x4;
SSP1CON1bits.CKP = 0; //clock idle state
SSP1STATbits.CKE = 0; //data valid position
SSP1STATbits.SMP = 0;
TRISCbits.TRISC3 = 1; //SCL1
TRISCbits.TRISC4 = 1; // SPI1-DI
TRISAbits.TRISA5 = 1; //~SS1