i can't understand SPI well

[mostafa_wahba]

hey all
i have a little problem in understanding the SPI
i want to send data from slave to a master and i don't know the wright connections and the wright code and also i want to know how will i transfer the data
should i send the data to specific port or i can use any port for the output
i'm using atmega16
thanks in advance

 

[FvM]

For slave operation with some speed, you're effectively tied to the ATmega hardware SPI unit and the respective dedicated pins. In addition, you need to organize your software in a way, that it services the SPI interface in time, particularly when using multiple byte transfers. Specific interrupts are available for this purpose.

 

[mostafa_wahba]

is there any problem from making master ic receive data and the slave send data?
because someone told me that master only send data

 

[FvM]

No, there's no principle limitation. For slave read, one data byte has to be hold available before the transfer by writing it to the respective communication register. Review the ATmega datasheet for details.

 

[mostafa_wahba]

i know that in the pic spi has 4 pins CS , SDI , SDO , CLk and in atmega they are SS , MOSI , MISO , SCK
and in mazidi avr reference the spi explained with SDI ,SDO and i don't know what's the pins in the avr that like pic ones
for example
is MOSI is like SDI?
is MISO is like SDO?
is SS is like CS?

 

[alexan_e]

Take a look at

https://www.edaboard.com/threads/224005/#post955148
https://www.edaboard.com/threads/224005/#post955276

Also look at


Alex

 

[mostafa_wahba]

thank you very much alex