In SPI, How the will Initialize the Slave?

[Surender Reddy]

In SPI, how the master will initialize the slave that slave is going to receive the data?

How many devices we can connect through one SPI (Ex: Atmega8)?

 

[milan.rajik]

For SPI devices there will be SS oe CS pin for Slave select or Chip select. If there are two SPI devices in a system then you select first device be pulling down or pulling up SS pin of that device then communicate with it and then disable SS of that device, Then similar thing when you want to communicate with second device. SPI is faster than I2C. For every SPI device yopu need 1 extra pin for SS pin. If you have 20 SPI devices then you need 20 extra pins for each SS pin + 3 pins SCK, MISO, MOSI for comm.