Friday, November 6, 2009


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.

Monday, August 10, 2009

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.

Wednesday, April 15, 2009

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 . Code is all in Subversion. It's all there, but I still need to create some build instructions and other documentation.

Monday, March 2, 2009

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 , updated the FX2 firmware and added from VHDL test code. Details at .

Saturday, February 14, 2009


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