Milkymist One RC2 Known Issues

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Here is the known issues found during debugging and testing RC2


[edit] Major errors

  • cannot boot after fast power cycling, need to ask Xilinx FAE
  • Power supply overvoltage and reversed polarity protection, see emails. This is fixed by adding two 5W 5.3V Zener diodes, one PTC fuse and removed L11 bead, see IRC.
  • Sebastien posted "the video input on my mm1 (which was the one we did the ESD tests with) just broke down on me. it detects a SECAM 525 signal even when there's nothing connected, and the picture is always black no matter what you do, a P/N: V9MLA0402 will be placed on each video-in source.
  • Switch to WM9707 codec for improved audio quality, see emails.
  • Fix intermittent "no FPGA configuration at power-up" problem, see IRC log. Add low voltage detector & diode to fix no-loaded standby bitstream from flash after power on.
  • Reduce video input antialias filter capacitors to 120pF, see IRC log and email.
  • ADV7125 Ground Pins wrong connections. In rc3, we don't follow that recommended connections since rc2 works well.
  • Production
    • parts swapped manually in wrong, must be R30 -- 4.7K ohm, R39 -- 330 ohm.
    • parts manually entered in wrong, must be R147/R148/R150 -- 4.7K ohm.
  • BoM

[edit] EasyFix

  • L19 should be 0 Ohm to fix video-in signal loss bug. See [1] and [2]
  • L3 should be 0 Ohm to fix Audio-in freeze device. see IRC talk
    • short L19 and L3 on your board. It should be an easy rework by anyone with a moderate experience with soldering. M1 PCB L19 L3.png

[edit] Minor errors and improvements

These errors do not alter the functionality of the board.

  • Schematic
    • Add bigger test point on top copper with circular mask to easily do some scopes.
      • 5V: TP33.
      • GND: TP34, one through hole header pin.
    • Add test points for DONE, PROGRAM_B and RP# pin.
      • DONE: TP35
      • PROGRAM_B: TP36
      • RP#: TP37
    • Change h/w version control of resistor set.
  • PCB design
    • Put one more via on U6 pin8 and U4/U5 Vcc pins.
    • Change Y2 to a different type like Y1.
    • Let J11 DC Jack footprint tighten to its body for better mechanical match later.
    • Slightly make "M" & "cc-by-sa" logo a bit bigger both sides. move text to some places a little.
    • silk screen: change "SW1" -> "SW_R", "SW2" -> "SW_ON", "SW3" -> "SW_L" <- I don't want that -lekernel
    • place MK1 microphone stays at board edge to face acrylic case and bend two pins in a 90 degree, [3].
    • place C36 nearby C30.
  • Materia
    • Incoming parts check: pins lifted? different mark?
  • Production/SMT
    • Notice that even incoming parts are not good, try to use AOI and manually visual inspection to cover the poor, cool and crappy soldering.
  • Testing
    • Use jtag-serial board for faster reflashing

[edit] Joerg's feedback

  • insert fuse between powerjack and first capacitor (see above). Add a diode parallel to first capacitor, to short inverse polarity and make fuse trip
  • cut connection from J11,pin1 to C142. Insert a 2A fuse slowblow
  • make L7 L8 L9 L10 L12 L20 0R (those L that are in regulator outputs together with the 100nF Cs)
  • the C's nearby are cruft then, one of two, as well
  • but don't hurt, so you might consider removing one of two, and make the other 200nF, for BOM reduction
  • scratch R182 pads, looks dangerous

Notice: above info just for references though. We finally only added one PTC 2A fuse and two 5.6V Zener diodes. see more experimental results on Protection of Reversed Polarity on DC plug-in.

[edit] Links

Milkymist One Schematic Change History

Milkymist One RC3 Known Issues

Milkymist One RC1 Known Issues

Milkymist One Power On Off Sequence

Protection of Reversed Polarity on DC plug-in

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