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fw/ERRATA: add hardware errata and ideas for future improvements

This commit is contained in:
Werner Almesberger 2012-06-29 22:20:56 -03:00
parent 60c8145991
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- 4.5 V rail was intended to provide the ADXL32x with a supply voltage
that's at a safe distance from its 2.4 V minimum. However, the current
circuit wouldn't work with the acceleration sensor operating at 4.5 V.
It turns out the system operates well enough with the 4.5 V rail joined
to the 3 V rail.
- the 6 V rail drops to 5 V after relatively little use. Need to improve
the power supply.
- connections between boards are sensitive to mechanical forces and break
easily in the high-g environment we have here. Should consider moving
to an FPC at least for the LEDs. A stiff support beam (e.g., an
aluminium rail) helps to reduce mechanical stress.
- the vertical resolution is a bit coarse. We could improve it and make
the whole system simpler by adding local demultiplexing with 74HC594
or 75HC595. Such chips could drive the LEDs directly.
- the battery pack needs room for a plug. (The original design assumed
the battery pack would be mounted on the stick, but this now seems
undesirable, due to the large weight. Current stick weight is about
120 g and each AA battery would add about 25 g.)
- the system really ought to have a button or even a joystick for user
input.
- once a button is added, we could have local-only operation with images
coming from Flash.