Week 10: Moo 2.0 PCB Modifications

Moo 2.0 Progress

This past week was devoted to mapping out the PCB board (and corresponding circuit schematic) modifications that will need to be made for the next generation Moo: Moo 2.0.  This began with making a component of the Wolverine MCU (MSP430FR5969) 48-pin QFN package.  I created a schematic symbol for the MCU from the datasheet and used the component wizard in Altium 10 (virtual connect to CAEN machine) to generate the corresponding footprint from the dimensions indicated in the datasheet.

After creating the component and swapping out the existing MSP430F2618 64-pin PM component from the schematic, I have begun slowly making the corresponding connections with the rest of the circuit board.  While some of the connections are trivial (Vss, Vdd, etc.), several of the pins are defined and placed differently on the new MCU (ADC ports, crystal, etc.).  It is worth noting the main differences between the two MCUs and what modifications we will need to make to the board. I believe that updating the schematic as well as the firmware to operate on the new platform will be far more challenging than rerouting the physical traces on the PCB board and is more prone to error, as well.  I have created the following (on-going) google doc to keep track of the design changes for the Wolverine chip on a pin-by-pin basis.

https://docs.google.com/a/umich.edu/document/d/1rRBA1XpxaT4seM81XRfJAb8Zv6Ewgvq1EuYT6sRaCwk/edit

Next Steps for Moo 2.0

  • continue to read through Wolverine MCU user guide and datasheet and make appropriate modifications to PCB schematic
  • continue to read through MSP430 design basics for more info on how firmware/hardware works
  • Verify schematic operation with Denis, TI folks (?), and others
  • Begin placing and routing new MCU on board

Applications of current Moo 1.1

Detecting Human Motion via tag rate

One potential application for the current Moo devices is using the inherent drop in tag rate of the Moo devices in the presence of humans to detect motion in a room.  Essentially, if a human were to stand between the reader and Moo devices, the transmission rate would change (i.e. drop to zero), thus behaving almost as a binary sensor to determine whether a human being is present or not.  I ran a simple experiment to verify that the tag rate will indeed change (https://docs.google.com/a/umich.edu/document/d/1htijqlbp-M36Qd0hf9DxoLl7tm29m0e1s7DlHBi1jOA/edit) in the presence of a human.  Building on this idea, I also ran an experiment using multiple reader antennas and multiple Moos in a straight line to see if it is possible to track human movement in a particular direction.  This experiment was also documented (https://docs.google.com/a/umich.edu/document/d/1L3HcSI5A6K1BFru7CkutJnyPxbUT-ZbOi7nSuUgQATg/edit).  However, the results were less illuminating because it the multiple antennas made it difficult to isolate the attenuation from human presence).

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