Chris Wilcox

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Everything posted by Chris Wilcox

  1. Chris Wilcox

    Delta Sigma Feedback Question

    I'm working through Mike's excellent book and am on the 1 bit (Delta Sigma) DAC chapter 16. I've also taken some time to peruse the Xilinx App Note 154 that is referenced in the chapter. In para 16.4 of the book, the VHDL 'code' in para 16.4 library IEEE; use IEEE.STD_LOGIC_1164.ALL; use IEEE.STD_LOGIC_ARITH.ALL; use IEEE.STD_LOGIC_UNSIGNED.ALL; entity dac8 is Port ( Clk : in STD_LOGIC; Data : in STD_LOGIC_VECTOR (7 downto 0); PulseStream : out STD_LOGIC); end dac8; architecture Behavioral of dac8 is signal sum : STD_LOGIC_VECTOR (8 downto 0); begin PulseStream <= sum(8); process (clk, sum) begin if rising_edge(Clk) then sum <= ("0" & sum(7 downto 0)) + ("0" &data); end if; end process; end Behavioral; The meat of the work is done here: sum <= ("0" & sum(7 downto 0)) + ("0" &data); This makes sense and works quite nicely on my DUO/Logicstart. I tested this using switches for the Data input and output the Pulsestream to an LED. My confusion concerns how this is implementing the Delta Adder in the App Note (which is actually a merge as explained in the App Note). I've managed to pretty much wrap my head around the App Note theory, but cannot understand why the copies of the MSB are not prepended to the sum(7 downto 0) element. Thanks, -Chris
  2. Chris Wilcox

    Papilio DUO not showing up on windows 10

    If you can, look into loading the WebPack that installs under native Windows rather than VirtualBox. Integration with DesignLab actually works, much less hassle. If you do, be sure to go through the steps to fix the DLLs.
  3. Chris Wilcox

    Is gadget factory moving sites or shutting down?

    Glad things are back! I just picked up a DUO (2M) and a LogicStart from Seeed and I was afraid I had been orphaned just after my purchase arrived. I was able to find the answer to my worry that the upper 5 LEDs on the LogicStart did not have limiting resistors (they are on the DUO) earlier today on the forums Working through the Introducing the Spartan 3E FPGA and VHDL pdf, my first foray into FPGA - enjoying the boards thus far.
  4. Chris Wilcox

    Papilio DUO not showing up on windows 10

    If ISE is running in VirtualBox, deselect the DUO in Devices->USB from the VirtualBox Menu. I ran into this when trying to load a bitfile from the Papilio Loader running under Windows 10.
  5. Chris Wilcox

    New (potential) user

    Hello all, thinking of picking up the Duo with a LogicStart shield. I'd like to possibly integrate with my Arduino classes at the HS level in conjunction with FIRST robotics - Our current learning platform is Arduino Uno based. I have a EE background with embedded programming experience but minimal FPGA design experience. I've read thru much of the VHDL intro (e.g. Freerange VHDL) and it seems fairly intuitive. Questions: Are there any issues with Windows 10 and any of the EDAs for this or other Gadgetfactory boards/FPGAs? Any idea when the larger boards (e.g. 2M Duo) will be available? Any other advice? Many thanks, -Chris