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Dual Link JESD setup for independent DAC cores

Category: Datasheet/Specs
Product Number: AD9174

I found this point on Product Highlight section(Page 1) of AD9174 datasheet.

I went through the Start-Up sequence for JESD mode setup and found ways to configure dual link(repeating SPI writes on register 0x300,0x475,0x453 & 0x458) respectively.

I have a doubt. Let's say I want to go for JESD mode 4, having L=4,M=4.Now configuring dual JESD link I would do as asked in the start up sequence section, but how do I know that link 0 corresponds to which DAC core, i.e. DAC0 or DAC1.and similarly for Link1 as well.

I wanted to have M=4 (2x complex(I/Q) channels per DAC core data path), so setting link 0 & link 1 separately don't tell me if M=4 corresponds DAC0 or DAC1 core.

Any suggestions on the same would be of much help.

Sourav

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  • Hi Sourav,

    Link 0 corresponds to DAC0 and link1 to DAC1. The physical lanes can be optionally remapped to different logical lanes, of which the first half will correspond to link0 and the second half to link1, as described in the screenshot below. 

    Your JESD mode will be duplicated per link. If you use mode 4 each link uses 4 lanes and 2 complex channels per DAC. You can set the NCOs/gain/etc differently for each link datapath, but the I/Q data is the same for both. Is that what you are asking?

  • Hi KB,

    Ya, I wanted to know the same.

    So if I understood correctly we don't have to manually set lanes to the link they belong to, its just that when we go for Dual link mode, then based on the JESD mode used, it uses that many lanes as x for link0, and increments it (based on L value), & for the second link it starts with x+4(irrespective of the L value) and then increments it the same manner.

    I check the register 0x308 to 0x 30B, I think I should leave it to its default value since as u mentioned that first four corresponds to link0 and the other half to link1.That should be fine correct?

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  • Hi KB,

    Ya, I wanted to know the same.

    So if I understood correctly we don't have to manually set lanes to the link they belong to, its just that when we go for Dual link mode, then based on the JESD mode used, it uses that many lanes as x for link0, and increments it (based on L value), & for the second link it starts with x+4(irrespective of the L value) and then increments it the same manner.

    I check the register 0x308 to 0x 30B, I think I should leave it to its default value since as u mentioned that first four corresponds to link0 and the other half to link1.That should be fine correct?

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