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About synthop

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  1. synthop

    SoundBlaster FM HDL

    Well, just to clarify, frequency resolution is 20 bits or about 0.047Hz, determined by the width of the phase accumulator and the sample rate. The phase input to the ROMs is truncated as is typical with NCOs but this doesn't affect the frequency accuracy. Even though the input to the sine ROM is 8 bits, phase resolution is actually 10 bits, as only a quarter of the sine wave is stored and symmetry used to translate it to all 4 quadrants. But yes this truncation does cause periodic phase error that typically shows up as spurious products in the frequency domain. Not sure if they're audible. Yeah the OPL3 has some additive synthesis modes too.
  2. synthop

    SoundBlaster FM HDL

    Sounds like a great project for someone with motivation. I'll help out as much as I can but this is a decently substantial project that I don't have time for. I bet someone in your user base has the know how and motivation to do this. Another alternative to converting to Verilog... if someone has access to Synopsis Synplify, they could generate a netlist with the existing SystemVerilog that could be imported by ISE. Orrr, sounds like you guys are VHDL people so just convert to that. As VHDL people you're already used to lots of typing!
  3. synthop

    SoundBlaster FM HDL

    I'm not familiar with DesignLab, but I assume it uses ISE/XST as the underlying synthesizer as you would be targeting the Spartan 6. As ISE/XST doesn't support the newer SystemVerilog features the code will have to be back-ported to Verilog2001, but that should be fairly easy. The only device specific construct in the code is the MMCM, which will have to be regenerated for the Spartan and the clock frequency of the external clock on the board. If the design doesn't fit the Spartan, you could pretty easily trim off the second bank of registers and essentially have an OPL2. The last sort of difficult part would be porting the CPU interface to whatever you are using on that board. But definitely doable.
  4. synthop

    SoundBlaster FM HDL

    Hi, I wrote opl3_fpga. Let me know if you have any questions. I love this stuff.