Milestone #1



Wireless Oscilloscope

The vision for this project is to create a measuring tool that is convenient and affordable for students in introductory engineering courses as well as engineering hobbyists. More precisely, we are building another version of the most powerful measuring tool in electrical engineering: an oscilloscope. Our product consists of a pen-like wireless oscilloscope along with software that can be accessed through any WIFI capable computer. Measuring will be done through the probe and displayed, in real-time, on a computer.

Block Diagram Details

Analog Front End (AFE)

Front end is the system that encompasses the probe tip to the inputs of the ADC. The probe tip will have ESD protection that would limit the input to a maximum of 150V peak to peak voltage. Following the probe tip, there will be a 10:1 passive attenuation with variable compensation stage comprising of a voltage divider with large input impedance (to minimize source loading). This attenuated signal will be fed to a gain/attenuator stage that will scale the input signal according to the user setting (this will be an op amp + multiplexer setup with various resistor feedback networks). After this, the signal will be converted to a differential to be fed into the ADC differential inputs.

Analog to Digital Converter (ADC) + Trigger System

The ADC we currently have chosen is TI’s ADS58B19IRGZT. This is an ultralow power ADC with high sample rate capability at 9-bit resolution. The part has one analog differential input. The trigger system will be used to implement the oscilloscope trigger function using a few analog components such as a comparator.

FPGA+DRAM

This system will oversee ADC data collection and storing it into DRAM. The we have currently narrowed down the FPGA to three Xilinx, which are all part of the Spartan-7 family. Our current plan is to also use the FPGA as a microcontroller (depending on resources available after ADC processing is implemented). This FPGA microcontroller will control the WIFI module and the USB debugging system. We have yet to choose the DRAM.

WIFI

This module will be used to send data to a computer. We have not chosen this module yet. The current requirements we have for this are: low power consumption, high bandwidth and potentially a 5GHz antenna.

USB Debugging

This part will be used to program the FPGA and to handle any firmware debugging we would need to do. We have not chosen this part yet.

Power Management

This system encompasses all the components necessary to distribute power and the correct voltages to all the components in the stylus.

Battery Management

There will also be a battery management subsystem that will be responsible for handling the charging of the internal battery and its power distribution.

Project Functionalities

        1. Our wireless oscilloscope will be able to measure arbitrary voltage signals from 15mVpp to 150Vpp using an ESD protected analog front end on a stylus-like probe.
        2. The wireless oscilloscope will be able to reproduce all the functionalities (math functions, cursors, trigger settings, etc.) of a regular digital benchtop oscilloscope through computer software.
        3. Internal rechargeable battery will allow the oscilloscope to be used wirelessly for long period of time.
        4. Singlehanded on-the-fly voltage/division and time division changing will be done using a capacitive touch button/scroll wheel on the stylus.
        5. Singlehanded on-the-fly waveform capture/screenshots will be done using a capacitive touch button on the stylus.