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Altera_Forum's avatar
Altera_Forum
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15 years ago

Configuring Altera FPGAs

I am currently working on a project using a cyclone ii device and I am not sure I understood the Configuration Cycle Waveform as described in ALTERAs config_handbook.pdf correctly : (Figure 1-1)

When the system powers up, the Low-to-High transition of CONF_DONE indicates the end of the configuration phase.

Then registers and I/O-pins are initialized before the devices enters the User-Mode, indicated by a Low-to-High transition of INIT_DONE.

My question is :

In VERILOG-1995 registers can be initialized using an INITIAL block.

My code consists of a large number of modules each of them using an INITIAL block.

Are all registers affected by that command initialized during that initialization phase as mentioned above (between CONF_DONE transition and INIT_DONE transition) ?

I am using QUARTUS 9.1SP2 software.

Thanks.

1 Reply

  • Altera_Forum's avatar
    Altera_Forum
    Icon for Honored Contributor rankHonored Contributor

    Hi,

    I think all registers must be initialized to either "0" or "1" before the device enters user mode. In case there is no initialization within the code (and the option "Power-Up don't care" in "More analysis&synthesis settings" is "On"), the QuartusII compiler can decide to initialize to either "1" or "0" to optimize device usage...

    (Similar to initialization in Code there is an "Power-Up Level" option in the assignment editor...)

    Regards