Milkymist One RC1 Known Issues

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Here is the known issues found during debugging and testing RC1 (also see http://www.milkymist.org/wiki/index.php?title=RC1_errata)

[edit] Major errors

These errors prevent parts of the unmodified board from working.

1, Connect P[15:8] instead of P[7:0] on the video decoder chip U21, check here.

2. The installed IR detectors do not seem to work. This is not a PCB problem and it can be solved by replacing the IR detector module with one from another source. Check here

3. The MIDI optoisolator is not suitable. Replace it with a 6N138S/6N138_X007 and lower R54 to 120 ohms. Connect pin 8 to 3.3V and leave pin 7 unconnected. Replace it with a 6N138S. Check here.

4. For USB to work reliably, 15K pull down resistors must be installed on the D+ and D- lines of each USB port (between the 24 ohm resistors and the ports). Add the possibility to make them pull-up resistors to 3.3V (i.e. add placeholders for pull-ups) so the USB ports could work in device mode with a small PCB modification. Check here.

5. Allocation and layout of Via, check here.

6, Eliminating spike depicted on decoupling capacitors of the DDR, see here. Also see Xilinx SP601 Reference design for more details.

[edit] Minor errors and improvements

These errors do not alter the functionality of the board.

  • Schematic

1. Add 1K pull-down resistor on ETH_RESET_N(specification says reset should be low during power-up), check here.

2. Add 1K pull-down resistor on VIDEOIN_RESET_N (the application schematics includes external POR circuitry), check here.

3. Add a 5V supply pin on the GPIO expansion header.

4. In order to be able to detect board revisions, route 4 FPGA I/O pins to placeholders for 0402 pull-up resistors. The combination of placed and non-placed resistors encodes the board revision. The RC2 board should be encoded as 0001 (ie place only 1 resistor) to distinguish it from RC1 which does not have any resistor.

5. To reduce audio output noise, power the LM4550 analog supply through an additional TPS76301 set to 4.3V.

  • PCB design

1. Add notch to mark pin 1 of J3 on silkscreen.

2. Expand a larger soldered thermal area under the pads of U10.

3. Indicate "+/- 5%" near J11 on silkscreen to let user use a DC 5V IN with +/- 5%.

4. Add a test point at the output of the MIDI optoisolator.

5. Add test points on the USB signals (3.3V FPGA side: VP, VM, RCV, OE)

  • BoM

1, Use red, green and blue component video RCA connectors for J18, check here. Next run will change this part to a new Component analog video RCA connector.

  • Production

1, Change 0402, 0603 a little thinner on footprint to meet IPC J-STD-001E.

[edit] Links

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