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AFE5809: AFE5809 Programming question

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Part Number: AFE5809

Hello Team,

One of our customers has some misunderstanding in writing coefficient memory block into coefficient RAM on the AFE5809 device. I’ll very appreciate you for some clarification:

Writing decimation filter coefficients to coefficients RAM consist of multiple writes of coefficient memory blocks to SPI address 0xC7. SPI address 0xC7 defined as a 112 bit word which is divided on 8 word of 14 bits each.

Single SPI cycle access of AFE5809 consists of 24 bits which are 8 bit register address and 16 bit data.

So what is the correct way write 112 bit  to 0xC7 register using 24 bit SPI cycle:

  • 8 SPI cycles access to 0xC7 register with SPI data consisting of [15..14] dummy bits and 14 bit [13..0] filter coefficient. ( bits 14 and 15 will be discarded by AFE5809 internal logic)

Or

  • 7 SPI cycle access to 0xC7 register with SPI data consisting of [15..2] coefficient data of one coefficient and two bits [1..0] from the following coefficient  

Thank you in advance!

Kind regards,

Mo.

  • Hello Mo,

    For Coefficient memory accesses, the SPI write is different than a standard SPI write of 24 bits.
    It will be a single SPI cycle access of 120 bits (8 bits of address followed by 112 bits of data with MSB first)
    The SEN should be low for the entire access time.

    Regards

    Praveen

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  • In reply to Praveen Aroul:

    Hi Praveen,

    Many thanks for the clarification.

    Kind regards,
    Mo.

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