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 +3V3