Introduction These are the consideration and design decisions I took when designing a transparent hub for low- and full-speed USB (that is, all covered by USB 1.1, and not high-speed as required by USB 2.0). A transparent 1:1 hub is a device with one male USB plug, and one female plug. It basically substitutes an [...]
About this post These are things I wrote down at different stages of introducing myself to Nios II and its environment. Nothing really consistent nor necessarily the right way to do things. Jots Open Qsys. Follow this post. Went for Nios II classic, used Nios/e (no Hardware multiplication, as the target device doesn’t have it. [...]
Introduction This post relates to Altera (or should I say Intel FPGA?) Cyclone IV FPGAs loaded from an ECPQ flash in Active Serial x 1 (AS x 1) mode. Things written below are probably relevant to other Altera FPGAs as well, but keep in mind that Cyclone IV FPGAs have several peculiarities you won’t find [...]
The classic way: $ export QUARTUS_ROOTDIR=/path/to/altera/15.1/quartus $ . $QUARTUS_ROOTDIR/adm/qenv.sh Or open a shell (will set path, but not a full environment): $ /path/to/altera/15.1/nios2eds/nios2_command_shell.sh This is good for compiling for NIOS etc.
Introduction This post outlines some technical details on accessing an Altera ECPQ flash from a Nios II processor for read, write and erase. A non-OS settings (“bare metal”) setting is assumed. And as a bonus (at the bottom of this post), how to program the flash based upon a SOF file, both with JTAG and [...]
Emacs’ (and hence XEmacs’) VHDL mode has an annoying thing about hopping in and “help me” with composing code. Type “if” and it tells me I need to add an expression. Thanks. I wouldn’t have figured it out myself. So here’s how to disable this annoyance: Add in~/.xemacs/custom.el, to the custom-set-variables clause ‘(vhdl-electric-mode nil) ‘(vhdl-stutter-mode [...]
OK, what’s this? This page is the example part of another post, which explains the meaning of set_input_delay and set_output_delay in SDC timing constraints. TimeQuest (Quartus’ timing analyzer) performs a four-corner check (max/min temperature, max/min voltage) and picks the worst slack. In the examples below, the worst case of these four corners is shown. It’s [...]
OK, what’s this? This page is the example part of another post, which explains the meaning of set_input_delay and set_output_delay in SDC timing constraints. As mentioned on the other post, the relevant timing constraints were: create_clock -name theclk -period 20 [get_ports test_clk] set_output_delay -clock theclk -max 8 [get_ports test_out] set_output_delay -clock theclk -min -3 [get_ports [...]
Introduction Synopsys Design Constraints (SDC) has been adopted by Xilinx (in Vivado, as .xdc files) as well as Altera (in Quartus, as .sdc files) and other FPGA vendors as well. Despite the wide use of this format, there seems to be some confusion regarding the constraints for defining I/O timing. This post is defines what [...]
Often I prefer to handle I/O timing simply by ensuring that all registers are pushed into the I/O cells. Where timing matters, that is. It seems like I/O register packing isn’t the default in Quartus. Anyhow, here’s the lazy man’s recipe for this scenario. In a previous version of this post, I suggested to disable [...]
