A Compact Wireless Modular Sensor Platform

1
A Compact Wireless Modular Sensor Platform
Ari Y. Benbasat and Joseph A. Paradiso
Goals Philosophy
Hardware Instatiation

• To simplify the rapid prototyping and testing of
  wireless sensor systems, it was decided to design
  a modular sensor platform. Overall, the goal was
  to allow the user to treat sensing as a
  commodity, i.e. allowing an application to
  trivially incorporate different kinds of
  measurement. There were three keys to achieving
  that goal
• Encapsulation Knowledge A single pane of a
  modular system can
• represent the best practices in a given field
• save a large amount of design time
• allow for easy upgrades.
• E.g., an RF single pane with a proper HF
  transceiver and antenna layout
• Reducing repetition of circuit design The
  creation of individual panes containing one or
  more such circuits can eliminate much of the
  drudgery of the design process
• Most systems involve reuse of known circuit
  blocks usually with only slight changes.
• E.g. serial line converters, power regulators and
  microcontroller support circuitry.
• Simplifying prototyping Rather than proceed
  directly to a final layout, this platform makes
  it possible to build a prototype to
• collect the relevant data
• provide a valuable proof of concept
• help detect flaws in the design
• provide a basis to begin the construction of
  necessary interface and analysis software.
• Given the above goals, we consider three key
  philosophies in the individual board designs

Sample Applications Lessons Learned

• We consider lessons learned in two categories
• Electrical
• Timing details become quite important as multiple
  boards are connected.
• Long sensor startup times can cause problems for
  polling-based systems.
• Digital ouputs measurement times can add up
• Power supplies and regulation also suffer for
  heterogeneous devices.
• More voltage levels mean more regulators, leading
  to increases in RF noise.
• Voltage level clashes between devices (eg sensor
  and ADC) also occur.
• Mechanical
• Strength of individual connectors is key in
  wearable applications.
• Must consistently provide both mechanical and
  electrical contact.
• Parts rated for large numbers of insertion cycles
  are a necessity.
• Possible orientations of the boards should not be
  limited
• Daughter boards and connectors should not
  interfere.
• Top boards only if absolutely necessary.