Overview of Status of Analysis, Design, Fabrication, Tests, etc.
This past week the team had great progress in kicking off components of the design and interfacing with the hardware via code. The team successfully implemented and communicated with the ADC using the beaglebone after consultation with graduate student James Strawson. The ADC consequently performed as expected, and the internal voltage reference maintained stability within the expected range. The team is beginning analysis on improving and assessing the ADC’s performance (oversampling to improve resolution). On the hardware side, the first revision of the PCB has been kicked off. After pursuing multiple avenues for quotes, the team decided that assembly by the vendor was not desired as it costs upwards of $400/board not including the cost of components. The team has mitigated risk in this regard by only choosing components with non-blind contacts (i.e. not BGA, ACF, etc.) and is confident in soldering the components individually. Moreover, design for the enclosure is underway, with all appropriate components currently in CAD and undergoing revision. The full breadboard circuit of the system is currently being tested to prove capability in capturing data properly.
Accomplishments from Previous Week
Development of codebase for project (see github for progress)
Successfully interfaced with ADC through linux kernel with beaglebone black
Implemented device tree overlay and pinmux groups for ADC
Developed mux switching sub-routines
Verified current source operation with 12V step-up regulator
Finished Rev 01 of Schematic/PCB and completed DRC and ERC for successful fab K/O
Kicked off Rev 01 PCB @ pcbfabexpress (Aaron to pick up on Friday in Sunnyvale, CA).
Goals for Next Week (list names after each item). Use specific and measurable objectives.
Solder components to fab’d board and begin testing (Aaron)
Continue development of code for verification and validation (Max, Jacob, Matthew)
Complete necessary proof of concept validation on breadboard prototype and PCB if time permits (All)
Complete slides for presentation and work on report (All)
Sponsor Comments from Last Meeting and Actions Taken to Address these Comments (indicate date of comments and if via email or in person)
(4/20/18) - Ken did not give any action items for team. He did mention that he believes adc accuracy won’t necessarily be an issue (as long as it is repeatable during trials) measurements will end up being differences between node voltages
Instructor Comments from Last Meeting and Actions Taken to Address these Comments (indicate date of comments and if via email or in person)
(4/18/18) - Jerry mentioned potential concerns with cooling of components if they generate enough heat inside the box (depending on amount of time the system is on). The team is pursuing assessment of this by estimating thermal energy dissipated inside the box with a component roll-up.
(4/18/18) - Jerry discussed accuracy of the ADC, and summing all potential sources of inaccuracy (INL, DNL, Drift, Gain error) to convey to Ken. After meeting with Ken, the ADC does not need to be accurate per say (since relative voltages are used), but rather it should be repeatable in a set of measurements. The team is still in process of adding the sources of inaccuracy of the ADC regardless, so that Ken is aware of its capabilities.
Comments from Other Students in the Class (indicate date of comments and if via email or in person)
None at this time
Risks and Areas of Concern
PCB full assembly (soldering everything)
Settling time of components during fast switching (need to assess further)
Resources or Information Required but not Available
None at this time
Schedule
Wednesday 4/25/18: Progress meeting with Jerry and Pedro
Wednesday 4/25/18: Sponsor meeting with Ken
Friday 4/27/18: Expected completion date of PCB fabrication (5 x ordered with complete electrical testing)
Budget (list amount spent and amount remaining)
$469.85 Spent (components and 5x PCBs)
$586.59 Remaining + $600 of shared shop expenses
Progress on Report and Webpage
Updates to the report have been ongoing. A second draft has been uploaded to the website.
Webpage is being updated with references constantly along with other pertinent documents.