• Content count

  • Joined

  • Last visited

  • Days Won


Community Reputation

33 Excellent

About mkarlsson

  • Rank
    Advanced Member

Profile Information

  • Gender Male

Recent Profile Visitors

1,182 profile views
  1. Open Bench Logic Sniffer with 64MB capture buffer

    Sorry but I stopped following the sigrok/pulseview stuff years ago since the development was in my view not the way to go unless you are prepared to do all the compiling yourself. Windows is supported in a very limited way with the nightly build of whatever development code they have that day. However, you can build the windows installer of the last release code on a Linux system yourself if you follow the instructions. The biggest problem is that on windows you need to replace the FTDI driver for the FT2232 chip with a driver based on the Linux libftdi driver. I have not managed to get that working since early 2014. This is really a question to the sigrok team though.
  2. Back to Basics

    At work we have switched most of our Spartan-6 products to Artix-7 and for the most part the switch-over was painless, the only area that needed a bit work was places in the code where we directly instantiated low level design elements (like serdes blocks, BSCAN_SPARTAN6 etc.) that had to be re-coded using 7 series elements, and the new way of setting contstrains. However, one area that Xilinx keep messing up is LVDS outputs, which we use lots of. On the Spartan-6 part that we used, only 2 of the 4 banks could have LVDS outputs. On Artix-7 all banks can have LVDS outputs but the bank must have VCCIO set to 2.5V! This means that Digilent boards like Arty and CMOD A7 and Avnet boards like miniZed etc. can't do LVDS output at all since all banks are powered by 3.3V! This is pretty lame since LVDS is the future for high speed I/O, just look at UHS-II sd-card standard where 2 LVDS pairs are added for high speed applications. As for my FPGA "hobby" busyness, I have no desire to develop an Artix-7 or Zynq based board and compete with heavily subsidized products from Digilent and Avnet. And there won't be any more Spartan-6 based boards made by me either (Pipistrello LX45 and Pepino LX25 are sold out and discontinued and once the Pepino LX9 boards are sold there won't be any more boards made). End of the road... I totally agree. I have a long history of designing custom chips, starting in the 1980's with schematic-based design entry for ASICs. When we switched to text-based design entry (i.e. HDL) in the 1990's the productivity gain was incredible. We could do much more complex designs and still understand what it did, and we could use all the tools developed for software to maintain the code (like CVS for code repository, using the text editor that we liked most for design entry, and simple things like text compare). Going back to schematic-based design entry is in my mind a huge step back. Magnus
  3. SPI to initialize TFT

    For a more detailed description of the first line see Magnus
  4. SPI to initialize TFT

    idle is set to 1 if all bits in counter are 1 (unary reduction operator AND) if internalSck is high then cs is set to 0
  5. FPGA as USB PIA

    Hi Tim, Cool. I will include the Linux version. Yeah, the sigrok p-ols driver is fifo mode only. In serial mode the (i.e. with a serial mode bitstream loaded and the FT2232H is serial mode) the board is basically a Open Bench Logic Sniffer with higher baud rate (921600 instead of 115200) and more memory (64MB instead of 24kB) and it should be trivial to modify the sigrok ols driver to support pipistrello in serial mode. Note that the SUMP protocol limits the samples to 256k so if you want to sample more you need to use the extended range registers that I added (see the p-ols driver). As for the sampling of TMDS data, you should be able to use the HDMI connector for that but you would need to add the 50 ohm terminator resistor packs on the bottom side of the board (the layout is prepared for this). Initially the plan was to support both HDMI-out and HDMI-in and an earlier XL9 board I made worked great in both modes but I was sloppy when I did the Pipistrello layout and did not place the CLK pair on GCLK pins . However, if you just want to asynchronously sample the TMDS data at 4x the bit rate then this should work fine since you don't use the CLK pair as an input clock. You would need to change the Pipistrello OLS code to use SERDES for sampling the data etc. but you should be fine from memory bandwidth standpoint (4 bits at ~1Gb/s is 500 MB/s and the memory controller on Pipistrello can easily do that when using the maximum burst length). If you want to work on this then I can hopefully give you a hand. Cheers, Magnus
  6. FPGA as USB PIA

    Should be back now. Please note that this code is for Pipistrello and might have to be modified for other boards. Magnus
  7. No, that's not "equivalent" - you did not declare wb_data_i in the verilog version like you do in the vhdl version so it defaults to a single wire. Try this: input [100:0] wishbone_in; wire [31:0] wb_dat_i; assign wb_dat_i = wishbone_in [59:28]; Magnus
  8. Unknown Papilio Board

    On DUO there is a third possible reason for this error - the FT2232H chip on this board has two jtag controllers (port A and port B ) and if papilioprog is trying to open the wrong one you will get this error. If that's the case then one option is to specifically open the correct port using the "-d device name" option. Without the -d option papilioprog will open the first one it finds.
  9. Unknown Papilio Board

    This cryptic error message means that it can't find a jtag device connected to the FTDI chip (the error message have been changed in later versions of papilioprog). There are two possible cause for this error - you either have several FTDI devices connected to the computer and papilioprog is talking to the wrong one, or the papilio board has a problem with the jtag wiring from the FTDI chip to the FPGA. Magnus
  10. No, the ft232R does not have an MPSSE unit, which is what the Papilio loader is using for JTAG. Magnus
  11. Loading the SPI Flash on the Papilio Pro

    The only difference between my version of the bscan files and the papilioprog bscan files is that I also drive flash_wp and flash_hold. The flash chip on Pipistrello can do quad-spi mode where flash_wp and flash_hold are used as data lines. The pullups on the board for those two lines are too weak to overcome the default spartan6 pulldown on unused pins so I define them as inputs. See attached file. Magnus bscan_spi_spartan6.vhd
  12. Loading the SPI Flash on the Papilio Pro

    This basically means that the data returned from the flash is 0. As you said, if it works with iMPACT then it's most likely not a hardware problem. Could it be that you are using a bscan_spi_xxx bitfile designed for xc3sprog with fpgaprog? The fpgaprog/papilioprog bscan_spi_xxx files are incompatible with the bscan_spi files designed for xc3sprog and you would definitely not get the correct data back if you use the wrong bscan file. Magnus
  13. Interfacing memory to papilio fpga board

    No, there is no reason why a board like that would not work. I would keep the wires as short as possible though. One option is to make the layout to match the papilio wing headers and populate the board with pin headers to minimize the signal length. The memory you linked to has a 12ns access time and you should be able to do reads and writes at 25 - 40 MHz. A quick rule of thumb is to add 5ns address output delay and 5 ns data input delay to the 12ns access time = 22ns access cycle time. You should be able to use this memory to generate video signals at 8 bits/pixel, 640x480. The problem is that if you want to dynamically update the video image then you would need bandwidth for both video readout access and video update access. For 640x480 VGA that typically means the you need 50 MHz pixel access bandwidth (2x 25 MHz video pixel rate). If this is your goal then you might want to consider a 10nS memory part. Here is a link to a zip file with a Eagle board layout for a memory board that fits the Papilio headers: It implements a 32-bit wide 2MB memory system using two 512Kx16 SRAM chips and an address latch to save pins. This board has up to 100 MB/s bandwidth using 10nS memory chips and can be used to implement a 16-bit/pixel VGA buffer with read/write access bandwidth. While this is a bit more than what you plan to do, it might give you some ideas. Magnus
  14. This is a port of the Plus Too code from Big Mess o' Wires to Pepino LX9/1MB. This code base have been dormant for quite some time but the folks at MiST picked it up a while ago and added more features like keyboard and sound support etc. The code supports a virtual SCSI hard drive via the sd-card socket. This is based on the MIST scsi code but the disk interface is quite different - the MIST board have a ARM processor that is handling the sd-card read and write functions and talks to the FPGA via SPI, while in the Pepino implementation the FPGA is directly connected to the sd card using the native 4-bit SD protocol. The interesting part of this project is that the 128KB ROM data is stored in flash memory after the bit file and is executed directly from the flash chip (the need for this is due to the Pepino LX9 RAM limitation, the MacPlus needs the full 1MB of RAM). It's possible to do this since the flash chip on Pepino (Micron N25Q128A) can operate in quad-spi mode at up to 108 MHz clock rate. In quad-spi mode, 4 bits are transferred on each clock instead of 1 bit. However, due to access time restrictions there needs to be dummy cycles between the cmd/address part and the data transfer part based on the clock frequency used. The default number of dummy cycles is 10 matching the highest clock rate (108 MHz). So with the default dummy clock settings a 16-bit word transfer in quad-spi mode will take 2 + 6 + 10 + 4 = 22 clocks, corresponding to 1 byte command, 3 byte address, 10 dummy clocks and 2 byte data. (BTW, there is a possibility to eliminate the command byte by using XIP, eXecute-In-Place mode supported by this chip, but it was not needed in this case). In this project the spi bus is clocked at 65 MHz and the Mac 68000 processor is clocked at 8.25MHz. The 68000 memory access cycle takes 4 clocks for an effective memory access rate of about 2 MHz, which means that there is time for 32 spi clocks for each memory access (65 MHz/2.03125 MHz = 32). So the 22 clocks needed to read one instruction in quad-spi mode will easily fit in the 32 cycle window. The full ISE project can be found here: For more info and a MacPlus disk image etc., see this link:
  15. Unable to upload the bit file

    You will get this message if the FTDI chip can not find a JTAG device in the JTAG chain. This will typically happen if there is a problem on the board with the FPGA JTAG connection to the FTDI chip OR if there are other FTDI boards present on the computer and the papilio loader happens to open the wrong FTDI chip (the default behavior is to open the first FTDI chip that it finds). BTW, the "insane" error message have been fixed in later version of the papilio loader to more clearly identify the problem (i.e. no FPGA chip found).. Magnus