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Altera_Forum's avatar
Altera_Forum
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11 years ago

Using OLD_DATA with 'tightly coupled memory'

We are moving a project forward to quartos 14.1 (and new hardware).

The qsys page for 'On-Chip memory' now lets you select single clock in order to get true dual port and OLD_DATA.

However there is a comment that 'Tightly Coupled Memory operation requires dual port & dual clock sources.

Lack of 'OLD_DATA' gave us grief on 9.1 and we fixed it by editing the memory wrapper.

Does anyone know if this is still a bug/restriction in qsys, or is the comment wrong.

IIRC the tightly coupled memory uses the 'address_stall' to hold the output data during

pipeline stalls. This seems to be defined for the Cyclone V we are targetting.

1 Reply

  • Altera_Forum's avatar
    Altera_Forum
    Icon for Honored Contributor rankHonored Contributor
    10 years ago

    Where did you see the comment on the Tightly Coupled Memory ....?

    You can just set dual port and single clock mode. It should work with old data.