The dDOS (digital diffuse optical spectroscopy) Spectrum Analysis Unit (dSAU) is a device being developed for Professor Darren Roblyer and the ​Biomedical Optical Technologies Lab (BOTLAB). It will aid in his research in the use of diffuse optical spectroscopic imaging for monitoring the effects of chemotherapy on cancer cells. The device must be able to simultaneously create six frequency sweeps that will modulate external laser drivers through user specified frequency ranges between 50 MHz and 400 MHz. Secondly, the dSAU must also be able to measure two waveforms, one from the aforementioned output and the other received from an external amplified photodiode that will measure the light scattered off the tissue from the modulated laser at a point. Furthermore, the Analyzer must communicate this waveform information to a PC running custom software for recording and visualizing the data. This software must also be able to set frequency sweeps and otherwise control the Analyzer. In order to meet these goals we designed custom printed circuit board(s) with six direct digital synthesizer chips for producing the output waveforms, a two channel 14 bit 250MSPS ADC for measuring the inputs and a ​Zynq SOC (ARM + Artix-7) with custom firmware and running Linux for controlling these devices and communicating with the PC. We also developed custom PC software written in Visual C++ 2010 and designed to work on Windows 7. All communications use 1000Mbps Ethernet over copper and are platform agnostic.

This project was carried out as a part of an ECE Senior Design Project for the class of 2014.

Revision A

Above is a block diagram of Revision A Analyzer as implemented and finished in May 2014. From organizational standpoint our team was divided into three major groups: hardware development, software development and firmware development. This is important to note throughout the report. While the boundaries of the hardware team are pretty clear the firmware and software groups do have a much fuzzier boundary. We will define firmware as any binary, FPGA bitstream, or related work, which runs on, or configures, the MicroZed?. The software on the other hand will be anything which runs on the computer. The distinction here is that the firmware, can be changed, but shouldn’t (thus the term "firm") and the software is simply an interface for talking for our final hardware solution and could be re-implemented without needing to redesign the hardware.

Our development environments are varied, but can be summarized as following:

• Hardware: Altium Summer 2009 through a BU license. Further details are discussed in the ​Hardware Report.pdf
• Software: Visual Studio 2010 using Visual C++, compatible with Visual Studio Express C++, further described in the ​Software Report.pdf
• Firmware: Xilinx Vivado 14.3 and Xilinx ARM GCC cross-compiler, which is described in the ​Firmware Report.pdf

Specifications

Parameter	Specification
Frequency Synthesis Frequency Range	0-400 MHz
Maximum Number of Daughterboards	6
DDS Input Clock	25 MHz (external clock support included)
Number of ADC Channels	2
ADC Bits	14 2's Complement Signed
ADC Sampling Rate	250 MSPS (external clock support included)
Noise Floor (Full Scale Referenced)	-100 dB
Motherboard Average Operating Current	0.885 A @ 5 V
Freq. Synth Daughterboard Average Operating Current	0.3 A @ 5 V
ADC Input Impedance	50 Ohms
FPGA to ARM CDMA Throughput	3 Gbps
Ethernet Transmission Throughput	170 Mbps
Firmware Swep Throughput	1 Gbps
Motherboard Dimensions	9.475" x 6.4"
Freq. Synth. Daughterboard Dimensions	2.5" x 3"
Full Assembly Dimensions (no box or standoffs)	9.475" x 6.4" x 2.6"

Hardware

Motherboard

• Altium Project (​zip)
• Schematic (​pdf)
  • Roblyer_dDOS_Undersampling_dSAU_MotherboardRevA_SchematicNotes
• PCB
  • Gerber Files (​zip)
  • Layout (​pdf)
  • Roblyer_dDOS_Undersampling_dSAU_MotherboardRevA_PCBNotes
• Bill of Materials (​csv, ​xls)
• ​Important Datasheets

Frequency Synthesis Daughterboard

• Altium Project (​zip)
• Schematic (​pdf)
  • Roblyer_dDOS_Undersampling_dSAU_DaughterboardRevA_SchematicNotes
• PCB
  • Gerber Files (​zip)
  • Layout (​pdf)
  • Roblyer_dDOS_Undersampling_dSAU_DaughterboardRevA_PCBNotes
• Bill of Materials (​csv, ​xls)
• ​Important Datasheets

Firmware

Software

Reports and Other Resources

• Slides
  • ECE Day Slides May 2014 (​pdf)
  • CDR Slides (​pdf)
  • PDR Slides (​pdf)
• Reports
  • Final Report / User Guide May 2014 (​pdf)
  • Critical Design Review Report February 2014 (​pdf)
  • Preliminary Design Review Report December 2013 (​pdf)
• Pictures (​web, ​zip)

Developers

Current Developers

• Dan Gastler, Primary Maintainer and Developer
• Fei Teng, Research Assistant in Darren's Lab
• Eric Hazen, Overseer

Senior Design Project Team

If the original team is to be contacted please contact the new maintainers first. Eric Hazen or Dan Gastler can redirect questions as needed.

• Christopher Woodall (chris.j.woodall <at> gmail.com), Motherboard PCB Designer & Primary Support Contact
• Thomas Nadovich, Frequency Synthesis PCB Designer
• Benjamin Havey, microZed-Zynq Firmware and Software Developer
• Caroline Ekchian, PC Side Frontend Developer
• Andy Mo, Server-Client Communications Developer

This Senior Design Team also won a Design Excellence Award at ECE Day 2014