introduction
This (new) week is devoted to system integration. On the nueval pages no other information could be found rather than ‘develop your work’:
- create a project plan
- track the progress
- summarise and document this.
QA and QC
The lecture deals with many ways systems can fail and how to mitigate the risks of systems doing so, by quality assurance (defect prevention) and quality control (defect detection). For a number of aspects (such as reversing polarity of the power supply) I will incorporate these aspects in the design. For Quality Control I use the following order of assembly and testing:
- testing optically for shorts, bad connections, solder bridges
- testing for shorts (multimeter)
- testing the power supply section (12V, -12V, 5V, 2.5V reference and -10V reference)
- THEN mount the microcontoller
- test 3.3V
- -> now move on to testing components in software:
- blinking LED
- printing to terminal (debug interface)
- measuring and printing analog inputs
- measuring and printing encoder data
- testing output to I2S DAC
- testing output to I2C OLED display
Risk mitigation
As discussed in the lecture there are many faillure modes to consider. In the following section I will briefly discuss the potential sources of error(s) and the ways to mitigate them. (STILL INCOMPLETE, TODO)
- mechanical
- loads beyond the elastic limit (not very relevant. The panel can crack when buttons are excessively pushed)
- misalignment, binding, flexures (solder sockets after mounting the plates?)
- wiring
- ripping up PCB traces (sockets are mechanically fastened to the faceplate)
- pulling wires out of connectors (IDC with strain relief, Jack sockets)
- strain relief: (use IDC socket)
- polarized connectors (use IDC socket)
- insulation abrasion, dielectric breakdown, shorts (no mechanical play)
- wire guides (for the backplane in the modular synth)
- wire harnesses (for the backplane in the modular synth)
- components
- MOSFET over-voltage, current, temperature
- inductive flyback, reverse protection diodes
- regulator reverse polarity
- processor over-voltage, GPIO current source, sink
- current limiting
- transient protection
- EMI shielding
- power
- budget, supply compliance
- batteries, lifetime
- switching + and - (protection diodes on +12 and -12 side)
- transient noise, processor faults
- wiring resistance, inductance
- bypass capacitors
- ground loops, mecca
- software
- memory leaks
- buffer overflow
- race conditions
- variable scope
- object interfaces
- dependencies
- obscurity
- manufacturing
- supply chains
- capacity
- collaboration
- data interchange
- fail fast
- feed-forward vs feedback development
learning outcomes
Goal of this week is to
- Create the project plan
- Track the progress of your project
- Summarise and communicate the essence of your project development
These points have been discussed on the final project page
evaluation checklist
- what tasks have been completed?
- what tasks remain?
- what has worked? what hasn’t?
- what questions need to be resolved?
- what will happen when?
- what have you learned?
lessons learned, tips and tricks
(or, the most insightful mistakes I made)
left for todo
- assembly and testing of the electronics
- assembly of the mechanical face plate, face mechanism and bowden cable drive
- integrate both
- expand the software beyond the test sketches
- put the design in an modular synthesiser
- rock!
reflection
Interesting week with a lot of planning, ordering components, boards arrived on time. Mechanical design is more work than expected … I decide to put most of (this week’s) files on the ‘design’ section.