HI everyone,

I want to transfer a byte from one microcontroller to another using SPI,
i just want to know if the transmitted byte is reversed in the other microcontroller.

 

start here

http://en.wikipedia.org/wiki/Serial_Peripheral_Interface_Bus


also, if you use a microcontroller with some built in functionality like the mBed from NXP, the SPI protocol is pre-written for you, you just call it and put data inside the function call.

 

i'm using a pic18f2331 to transfer data to dspic30f6010, but in the pic18f2331 datasheet : "The SSP consists of a transmit/receive Shift Register (SSPSR) and a buffer register (SSPBUF).The SSPSR shifts the data in and out of the device, MSb first. The SSPBUF holds the data that was written to the SSPSR, until the received data is ready."

in the dspic datasheet: " Data is transmitted out of bit 7 of the SPIxSR for 8-bit operation while it is transmitted and out of bit 15 of the SPIxSR for 16-bit operation. In both modes, data is shifted into bit ‘0’ of the SPIxSR."

Does this mean that the data will be received in the dspic in a reversed way than it is in the pic?
I didn't understand it completely, and it's the only information that i could find concerning transmission, and i read the link you sent me
thank you for your help

 

In the usual case SPI data is transmitted MSB first and enters the destination shift register at the LSB. After 8 clocks that original bit is now in the MSB. Same for the data on the reverse path. Some SPI hardware allows you to choose which bit goes first on the wire.

 

yeh, if that's the case then i have no problem.
i'll test it and see