Hardware Errata
This page documents some issues with the hardware.
Rev 3
- Footprint for RTC backup battery (BT301) is backwards
- The + terminal of the battery connects to the GND node, and vice versa.
- Resolution: Populate battery in reverse
- RTC charger should be powered by system +3V3 rail
- It's powered by the SoC's own 3V3 rail now, which toggles off during reboot
- Use instead the system +3V3 rail
- Incorrect power-on reset behavior
- There is no reset pulse generated on boot-up (by an external reset generator… which we don't have. lol) which causes spurious boot failures
- So, we should add a supervisor for the reset line
- Generate a power on reset pulse of ~1 sec with the +5V rail
- We may need to shorten the reset delay on the +3V3 voltage supervisor line
- Alternatively – directly use the +3V3 input to switch it
- This was caused by the RTC charger coming off the +3V3 SoM rail. Using the system +3V3 rail resolves this
- There is no reset pulse generated on boot-up (by an external reset generator… which we don't have. lol) which causes spurious boot failures
- Pulse shaper stuff
- Adjusting it sucks as TP501 is on the analog side of the filter, rather than the nice, pristine digital from U507
- Fix: Add another test point at the output
- Alternatively, we can probably work around this in software (with a special calibration UI?)
- Possibly expand the adjustment headroom
- Adjusting it sucks as TP501 is on the analog side of the filter, rather than the nice, pristine digital from U507
- Front panel connection
- The pinout of the connector is mirrored (left to right) with respect to the front panel when assembled
- We can probably leave this (using a longer flex to compensate) or fix it on either the front panel or controller board revision (probably the controller board)
- Rear case fan (M501) connector sucks
- The location is awful (it will be right underneath the analog board)
- Relocate it elsewhere - but where?
- Where VBUS LED is chilling
- In the back by the expansion connector
- We'd need to relocate some of the expansion IO stuff, like the termination and so forth
- Power supply section sucks to assemble
- Is there anything we can do to make this less awful
- Also, add an easier way to power the board off DC
- Spring/screw terminal near power supply area