Grub-ing

Just got a nice Gateway quad-core PC to speed up FPGA designs, so time to install Debian Linux on it. Install went smoothly, until I tried to boot into Linux for the first time. Then I get error messages:
ata1: softreset failed (device not ready)
ata2: softreset failed (device not ready)
and Linux hangs.
After a lot of Google-ing and hacking (and hair-pulling), I finally found the problem: The Debian installer set the boot partition on the SATA drive to /dev/sdb3, and it really should have been /dev/sda3. Still get the "softreset failed" errors, but Linux boots and seems to operate normally.
Thinking about the problem: I used a USB DVD drive for the install, and then disconnected it before booting. I suspect the DVD was sda and the sata disk was sdb during the install, and the sata became sda when booting without the DVD drive.

915MHz signal with a 100MHz A/D

I've been using a Radiotronix DP-1205 RF transceiver that operates in the 915MHz unlicensed ISM band. The power level, operating frequency, FM deviation, etc., are set using the SPI serial interface. So I decided to see if my MHZ100Q A/D PCB could see the signal. I bypassed the antialiasing filter and associated buffer, and then coupled the transceiver signal to the input.
It Works! The signal is low amplitude (less than 10% of full scale), and there are a lot of spurs 20dB down or so, but the carrier is clearly visible. The 902 to 928 MHz band is being undersampled at 100 MHZ so it shows up at 2 to 28 MHz in the digitized signal (in full compliance with Nyquist's rules).
The A/D is only spec'ed to 550 MHz, so I wouldn't trust the signal and distortion levels, but it's definitely a usable signal.
More details on the MHZ100Q project site at Source Forge.

MHZ100Q - on sourceforge

I can now digitize one signal at 100MHz using my A/D card, capture in the Digilent Xilinx FPGA board, and upload to a PC via the USB port. I'm using Octave to upload and display the data, making a sort of oscilloscope. So I decided it's time to create a sourceforge open-source project.
It's http://mhz100q.sourceforge.net . Code is all in Subversion. It's all there, but I still need to create some build instructions and other documentation.

Cypress CY7C68013A (FX2) USB to FPGA

I just got the USB interface working under Linux for the Digilent Nexys and Nexys 2 FPGA boards. Started with some ideas from the blog at braiden.org , updated the FX2 firmware and added from VHDL test code. Details at www.sensicomm.com/main/projects/fpga/ieee_fpga.shtml#nexys_usb .

Noise-blog

Created a separate blog for less-technical happenings. (Signals here, random noise there). It's at noise-blog.sensicomm.com. Alternate is joerothweiler.blogspot.com (most noise-related names on blogspot are already taken).

Quad 100 MHz A/D PCB

The paying customers are taken care of for a while, so it's time to update the blog. I want to test some DSP on the FPGA (filters, RF signal modulation/demodulation, etc)., so I need A/D and D/A capability. I could buy a board, but it's more fun to build my own. So I settled on a quad, 8-bit, 100MHz board that interfaces to the Xilinx or Digilent board via the 100-pin FX/2 connector. The block diagram shows one of the 4 channels. As a test, I'm capturing a signal and displaying it on the VGA output. The signal is looking reasonable. More details on my website:
http://www.sensicomm.com/main/projects/fpga/quad_100mhz_a2d.shtml

FPGA frequency counter code.

An FPGA project that does something useful: implements a frequency counter using the Xilinx Spartan 3AN development board. Basically consists of two counters and the AX8 uC core. The first counter generates a 1 Hz timing signal from the on-board 50 MHz crystal oscillator, and the second counter counts the signal under test. The AX8 core runs a simple program that reads the count value and formats it for display on the LCD.
The attached image is counting the frequency of a VEX RC transmitter using a 75.97 MHz crystal. The measured count is 75.971459 MHz, which is within 0.002% of the expected value. The development board uses an xtal oscillator marked AGXO-751L 50.000 A. I found a datasheet at www.inysa.es indicating that A versions are 100ppm, or 0.01%, so the measured value is well inside the tolerances.
I'll be posting the code when I get it ready.