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Hardware Errata

This page lists some issues with CPU board hardware, as they are discovered, and some workarounds.

Rev 1

  • /I2C_IRQ's external IRQ line conflicts with ENCODER_A
    • Move /I2C_IRQ from PA7 to PA10
    • Rework required: solder line from pin 11 (/IRQ) of U101 to middle of J302 (TXD)
  • Status LED (D302) footprint is wrong
    • The common (+) and red pins are swapped
  • Footprint for MMBT3904 transistors (Q101, Q301) are slightly too small
    • The two pads side is slightly too much spacing between pads
    • They are still solderable, it just looks ugly
  • NOR Flash (U303) is actually 4Mbit
    • This is the part I actually had lol
  • Power LED driver doesn't work
    • The weird trick with the two resistors doesn't seem to work… like, at all
    • We'll have to revisit how this is controlled (external logic? sacrificing another pin?)
    • Footprint notes
      • Copper size on the pads could be increased
      • For mechanical retention of the switch, nudge the outer (switch) pads in by a small amount
  • Switched front/rear I²C bus (from mux to MCU) is missing pull ups
    • Need to insert these between the mux (U101) and microcontroller
    • Rework required: Bodge in a pair of 2k2 resistors to +3V3image-1648709305027.jpeg