Milkymist One RC3 Known Issues
Here is the known issues found during debugging and testing RC3
Contents |
from contributors
- From Joerg & Werner [4], for Adam's review
- 1. Short L3 to fix audio problem
- 2. R11 should be 0R otherwise we loose stereo separation for the CD input on the expansion header
- 3. joerg would put ~50 pF in parallel to R23 and R24, to filter HF and to absorb ESD (there's no ESD protection on line in)
Major errors
the intermittent loss of video input
- the intermittent loss of video input, replace L19 with short connection by soldering on run3 boards. In RC4, will have no this part[5] with routing in wire to connect two planes under video decoder, see page 95, figure 41.
darn of never booted up
- darn of never booted up about solutions from reset IC and diode:
All RC3 boards have been finished/verified with hardware patches that Sebastien Bourdeauducq and Werner Almesberger got this done: 1. R30 and R157 were changed to 10K ohm. 2. R60 removed. 3. C238 added 220pF. Note: the added diode in red color have been removed now. Thus is called fix2b circuit instead. See previous rework steps of h/w patches here during producing rc3 boards.
Proposed pre-rc4 reset schematic
- Proposed pre-rc4 schematic for design verification on RESET to solve nor-corruption.
Draft Schematic for pre-rc4 design verification: proposed M1 reset circuit improvement, 74xxx1G, pre-proposed reset schematic and reset circuit vs. USB inrush current by Werner. So proposed circuit is : U24 is changed to Diodes Inc. APX803-40SAG-7 4.0v reset ic, powered from 5V. Replace D16 with AND NXP 74AUP1G08GW,125 gate. DNP C238/R60. R30/R157 keep 10K ohm(still connected to 3V3). [1]. Add two 4.7K Ohm pull high resistors to 3.3V with individually at Nor chip pin 55 WE# and pin 54 CE0, see details.
- L1's footprint needs to be smaller and same as 0402.
Minor errors and improvements
- Downsize the pin number of J3 to two 1x3pins 2.54mm pitch header footprints of Jx and Jy and DNP in rc4 and close to audio codec. See J3 redesign for rc4 on list.
- to remove the need for the metal sheet, Joerg suggested using 5mm wide endless aluminium sticky tape and attach two stripes across the diagonals of the bottom PCB side. He would connect them to the spacer only on one side, in the middle crossing they would ideally be isolated by the glue. [6]
- We are thinking about replacing the VGA connector with a DVI-I connector (single-link), for some notes see mail and irc log, direct connection.
- Werner propoased that adding another same pins of J21 to make a "U"-shaped and need to fully specify the expansion system and decided to use like female receptacle socket, so that DIY can build small circuit to plug on it.
switch to ADV7181C
- switch video coder to ADV7181CBSTZ, ADV7181C_Manuals and see discussions: [7], [8], a composite video source plugged into middle RCA connecor (BLUE) works
1. Remove L14 ~ L16, C202 ~ C207 entirely 2. Short L14 ~ L16 3. replace U21 with an ADV7181CBSTZ
add USB Power Switch
- usb power switch
Draft USB power switch schematic for pre-rc4 design verification: see [2], [3], an agreement before rc4 for design verification: 1. Add an active low usb switch AP2142ASG-13 2. connect FLG1 and FLG2 on FPGA side for indicator feedback and connect each for a pull-up 10K ohm to 3V3. 3. pre-placing an existing C178 220uF still there then later determine if needs it after verification. Connects pin2 IN to 5V net not 3V3. 4. Connect existed expansion header J21 reserved pins to EN1 and EN2 to let fpga can be able to control usb power. 5. Connect another J21 two pins to two LEDs being as individual indicator.
- Werner proposed adding LEDs to the ports to indicate [9], LEDs on the bottom, center placement
- demand = patch wants to use feature X but nothing seems to be connected
- activity = an aperiodic flash every now and then
- problems = maybe periodically blink
- cheaper led may be http://search.digikey.com/us/en/products/APT1608SGC/754-1121-1-ND/1747838 (only use 1 type of led, including the 3 existing ones)
- total of 14 new leds proposed: 2*dmx, 2*midi, 3*video-in, power, 2*usb, ir, dvi-i, ethernet, memcard
- if there is enough space, Werner proposed going go 4 USB ports, by using 2*2 connectors such as http://search.digikey.com/us/en/products/690-008-621-013/151-1085-ND/806184 or http://search.digikey.com/us/en/products/67298-4090/WM17130-ND/859139
- rc4 H/W control resistors: R176/R177 1K ohm, R178/R179 DNP.
R4 draft feedback
Items below have not been finished yet, see latest R4 draft
1. establish software on m1 to be in full control and awareness of what is going on, including cable insertion/removal, so review all I/O's circuit. Inlcude DVI-I pin16 detect.
2. for those audio 47 pF paths, if found Zener with suitable capacitance, then will add and remove those 47 pF.
3. J21.1/2 Jumper, if implement 'Crowbar' idea
4. find a flat Y1
5. a) the microsd opening should not collide with the jtag-serial board, so either move the microsd aside a little, or the jtag-serial a little. b) the position of the jtag-serial connectors on m1, or the ethernet connector, should be such that a fully RECTANGULAR jtag-serial rc2 would fit c) the distance from the jtag-serial USB connector to the side wall(ethernet connector side) should be 1-2 mm more d) rearrangement of all top side part's references.
Links
Milkymist One Schematic Change History
Milkymist One RC2 Known Issues
LVDS, CML, signal conditioning/equalization, jitter/crosstalk, and high-speed transmission line topics, see here.
