Author Archives: pgfeldman

Thomas.DeVito 1.21.2011

MISC:

  • Spent most of the day switching and setting up the printer for people
  • I could not find the hp solution center software for windows 7.  This is needed to set a destination for easy scanning

KF:

  • Still looking for a good chip to control the gain on our amplifier chip
  • I2C needs to have a 1k resistor connecting each signal to 5v coming from the usb-i2c adapter.  This is called a pull-up resistor not sure why its needed.  Pull-up is when you connect something to the high side, pull down is when you connect something to the low-side or gnd.
  • So far I have found big chips with large resistances and tiny chip with good resistance range.  I am leaning towards a 14 pin tssop package which will need an adapter(tiny but at least proto advantage sells the adapters).  The optimal resistance of the i2c variable potentiometer is 5k ohm  which will be in series with another 5k ohm fixed resistor.  The reason 5k is the target rating is because the mechanical variable pot we have has a maximum for 1ok.  The max volume we want happens around 7680 which is approximately half of the maximum resistance of the variable pot in series with a 5k resistor.  Each step in a 7bit(128 step) 5k variable pot is each to about 40 ohm, which means we have roughly 36 steps of control over the volume range we want to use.  Most of the chips I am looking at have dual potentiometers which means we will only need 3 to control 5 fingers.
  • Tried putting a resistor between the + side of the amp output and the speaker to see if anything good would happen due to confusion of how one of the ICs worked.  Nope nothing good happened as expected so I must have been misreading tat ones documentation.

Phil 1.21.2011

7:30 – 3:30 VISIBILITY

  • Deployed Dong’s changes to PPM. All went well. I also ran TRUNCATE on the query_logs table and the size of the backup went from 78 megs to 4.5 megs. It was easily 90% SELECT statements. I asked Dong to only log DB access that affects the tables. That should keep things under control and make it more searchable.
  • Working on my Java db accessor classes. Decided that I’m going to work on building FLAILS to do this. it’s a good opportunity, and the other objects were just dissimilar to be annoying.
  • Took a detour into the javax xml parsing code and it still sucks. Dom4j has moved from dom4j.org to sourceforge. Had a bit of cognitive dissonance for a while at the website.
  • Added dom4j utilities from MavenAssist to JavaUtils, and found that we had commented out the part of MaveAssist that puts the deployment urls in the POM. That’s back in and we have a new Maven on the repo.
  • Created a SQL table from describeType xml!

Christine 1.20.2011

  • Read through Visibility 4 document. Need to talk with Phil on next steps.
  • Took a look at the assets directory issue (b/c it was driving me bonkers). I think it may have something to do with how Maven and Flex interpret their directory structure.

Christine 01.19.2011

  • Dong helped me fix MavenAssist problem (due to my blindness)
  • Could not reproduce Phil’s AirfileImageAppMaven error. Could be something specific to his machine. At least we know Maven and Flex can work together on Mac and Windows. Unresolved issue: Incorrect location of the assets directory. Maven places all files within Flex assets directory under target root directory. Need to look into why
  • Received Phil’s Visibility 4 Initial Plan document to read through

Mike 1.20.2011

  • More hard-coding of prototype quad charts and reports:
    • Made a real looking quad chart with images, html text and fake looking links
    • Filled in the report with better formatted text and some more tables
  • Sent a detailed email to Alan explaining how to upload files to the blog
  • Talked to Brian more about what a quad chart is and how it should work with the reports

Thomas.DeVito 1.20.2011

Computer controlled amplifier:

We need 5k ohm digital potentiometers, more of those amplifier kits, and an i2c multiplexer to route the signal.  The other chips will be useful when we want to make every thing smaller.  The steps are limited but with the right configuration of resistors, I should be able to get the range we want.

I am going to have to double check the sizes to make sure they are all workable.  There may also through pin versions of the circuits.  Surface mounting isn’t too hard but it does mean that you need a PCB.

Strain gauge durability:
The BTP-5 strips have best spacing between the terminals.

Things I need to buy:

  • Fine soldering tip
  • Fine solder
  • Flux

Dong Shin 01.20.2011

  • PPM Changes
    • continue working on Financial Status
      • added Summary to FinancialStatusDataGrid
      • added FinancialStatusData.as
      • added DateItemRenderer – use dateFormat string to format, currently DD-MMM-YY and MMM-YY
      • modified CurrencyItemRenderer to handle Summary Data
      • layout is almost finished

Phil 1.20.2011

7:30 – 4:00 VISIBILITY

  • Pinged Kristie C. about a followup demo. We’re trying to schedule something for next week either here or at S2F
  • Pinged Anne about scheduling a + meeting
  • Testing Dong’s update. If everything works, I’ll roll it in this afternoon. Looks good.
  • Working on Project Tracker
    • Added ProjectInfoObject
    • Added EntryInfoObject
    • Added HistoryInfoObject
    • Added StatusInfoObject
    • Added TypeInfoObject
    • Abstracted RemotObject DB creation into base class, cleverly named ‘BaseObject’

Mike 1.19.2011

  • Finished entering in data for the sample report
  • Continued putting the framework together by adding in the module loading code and creating an example application that loads a module and creates instances of the classes loaded

Phil 1.19.2011

7:30 – 4:30 VISIBILITY

  • Got a big delivery of FP stuff yesterday. Brought it in along with the tweezers and ruler.
  • Project creation today
    • Added Menus
    • Added Project Panel
    • Added States

Thomas.DeVito 1.18.2011

Strain Gauge Durability Problem:

  • The optimal solution is to get more of the backed silicone strain gauges.  However these are a bit expensive ranging between $8-10 each.  If we didn’t have such excess of naked strain gauges, this might be a better option.
  • Another type of strain gauge is the foil type.  This type may be worth experimenting with before the productization stage because they are much less sensitive.  With our current strain gauges, I have to turn the amplifiers almost as low as they will go in order to get a good range of force.  One potential drawback is that, although I may be able to get a better range with this type, it may come at the cost of a higher dead zone.  These are approximately $27 for 5 which is still way more expensive then using our excess supply.
  • Since the main problem comes from the gold strands breaking, the most cost effective solution for more durability, is to use bondable terminal pads.  These are are essentially the same thing the backed strain gauges are attached to.  With these, I should be able to isolate the delicate parts from the strain of the heavier sensor wires, by having better anchoring points on the side of where the strain gauge is attached to the metal.  It may also be possible, to mount the gauges directly on the isolator and make a packaged gauge like the ones we have.  Doing this might also help dull the sensitivity the same way the backed ones do eliminating our potential need for foil type.
  • Some documentation on these terminals can be found here: http://www.omega.com/Pressure/pdf/Bridge_Completion_Resistors_RES.pdf
  • I need proper measurements to determine which ones to get. I think it should be about the same size the prepackaged ones we already have.  I don’t think having smaller spacing would be very solder friendly.

Formula for strain gauge Gauge Factor.  Just found this, might come in handy.

GF=frac{Delta R/R_G}{epsilon}
ΔR is the change in resistance caused by strain,
RG is the resistance of the undeformed gauge, and
ε is strain.

Phil 1.18.2011

8:30 – 4:30 VISIBILITY

  • Larry needs a VISIBILITY architecture diagram? Yep. Working on that. Done.
  • Sent Christine a snapshot of my User Settings
  • More work on the project tracker. Finished login.

Mike 1.18.2011

  • Working on porting all of my sandbox and other segregated code in to several mavenized projects that are shared on SVN and making example apps for parts of the code:
    • Started with the basic ones stuff, the logging screens, config loading, and data handling stuff
    • Added styles and skinning code + example app
  • Got an email from Alan with new report data, working on hardcoding that in to a quad chart prototype