Forum Discussion

Altera_Forum's avatar
Altera_Forum
Icon for Honored Contributor rankHonored Contributor
15 years ago

LAB Carry-In/Out

Hi!

I havte to make a ripple carry adder for a Cyclon II FPGA, the adder module is working properly but not using the LEs carry chain connections (LAB Carry-In, LAB Carry-Out). My question is that how can i made the Quartus II to use the internal carry chain? (if it is possible)

Auto Carry Chains set to On and Ignore Carry Buffers set to Off at the settings menu.

The LPM_ADDER module use that chain, mines why not?

2 Replies

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

    Finally i made it :) Using the carry_sum primitive between the full adders forces the compiler to use the internal carry chain.

    Later i could post an example if someone is interested.
  • Altera_Forum's avatar
    Altera_Forum
    Icon for Honored Contributor rankHonored Contributor
    12 years ago

    --- Quote Start ---

    Finally i made it :) Using the carry_sum primitive between the full adders forces the compiler to use the internal carry chain.

    Later i could post an example if someone is interested.

    --- Quote End ---

    Hi,

    I'm working on a project that need to use the internal carry chain between two full adders. Could you please post your example here. Thanks so much.