1787 FDSP number of instructions

Question

What controls the number of instructions available per frame in the 1787 FDSP core? Is the number always 64, or will it sometimes be less than that? The datasheet says "The core is controlled with a 27-bit program word, with a maximum of 64 instructions per frame." But the datasheet does not say how the maximum is obtained nor how the setup of the FDSP affects the number of instructions. Thanks in advance for any help offered.

galvinpjg · Accepted Answer

User2,

The FDSP clock is 24.576MHz. The FDSP_RATE sets the FDSP frame rate, which can be configured up to 768kHz. So if FDSP_RATE = 768kHz, then 24.576MHz/768kHz = 32 instructions max per frame.

If the FDSP_RATE is 384kHz, then the max is 64 instructions per frame. However, even if the FDSP_RATE is less than 384kHz, the max number of instructions per frame is still 64, since that is the maximum number of instructions that the FDSP supports.

So there are some instances where FDSP_RATE is high enough that the max number of instructions is less than 64, but there will not be more than 64 instructions available.

Please let me know if there are any other questions.

billww · Answer

Thank you very much!

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1787 FDSP number of instructions