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SPI interface with peripheral devices

Sir,
I am learning SPI interfacing. I am using P89V51RD2FA microcontroller.
And I have to interface it with a device using SPI interface but the problem is that I don't know what to do when I have to obtain data more than one byte.

Like in my case I need 3 bytes of data from the device. So after the usual write commands(giving command to read and the register to be read) and all, I am supposed to send some dummy byte which will be 0s. I wish to know that will the device return me three bytes just by one dummy byte or I need to send one dummy byte for each byte to be received.

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  • Sir,
    the code is not completely correct.
    Also there is some confusion it will be simpler if u could tell me how to send three bytes.

    According to me since SPI is duplex there should be no problem if I do in the following way

    like
    sending word
    dummy byte
    data obtained 1st byte
    dummy byte
    data obtained second byte
    dummy byte
    data obtained 3rd byte

    each dummy byte I send will return me a byte of data due to shift registers present.
    Is it the correct way????
    For doing this I will be making use of interrupt signal.