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saybur

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Everything posted by saybur

  1. When I had trouble doing this, I had to get into scsi2sd-util and hack in additional debugging to get more than the a terse "things didn't work" message. I don't have the modified versions I made, unfortunately. To roll your own, in scsi2sd-util.cc there's a (myHID->scsiSelfTest() ? "Passed" : "FAIL") statement. I believe the value returned there is the same integer returned in the firmware's self-test, defined in scsiPhy.c, where certain bits are set if particular tests failed. You could change the line so instead of doing a pass/fail conditional it just writes the results of s
  2. Ah, I get what you guys are aiming for. Just to explore the concept: It looks like a 2.5" HDD is about 100x70mm, which is basically the same size as this board, so the circuit could probably still fit OK. You'd want to keep the base SCSI interface and SD card, but rip out the ENC28J60 and replace it with some kind of wireless access device. That part might be problematic; the ESP8266 type devices have their own TCP/IP stacks, but the Nuvolink protocol assumes lower-level access to the network. It looks like some people have figured out how to make the ESP8266 enter promiscuous mode
  3. On the power side, after doing some more research I don't believe the USB-C approach will work easily. The ADC pins on the Xmega are all blocked in the current layout and I'm not keen on changing that if I can avoid it - it took quite a while to arrive at the current layout, I'm pretty happy with how things are, and it has been tested to work. There are some external ICs to support USB power but they seem to all be in hobbyist-unfriendly packages that would make this (already tricky) board harder to solder. As for sourcing from TERMPWR, after doing the math I'm leery of doing that.
  4. Thanks! I'm not sure the circuit could fit into that form factor easily. What is the use case you're thinking of?
  5. No, I think you're right, from what I've heard most chargers (especially cheap ones) don't seem to follow the rules and just deliver +5V until they hit their limits (or Bad Things happen, the Big Clive YouTube videos on those things are hair-raising). I'm more concerned about plugging the board into a computer for programming, where the amount of power available is likely to be restricted to the USB spec.
  6. Definitely. My only concern with USB is the power negotiation step; I figure this board has a peak draw of ~950mA, including the terminator, which would exceed standard USB's 500mA. When you get into the higher power levels, AFAIK you have to actively negotiate with the supply, which is more complicated than just throwing a barrel jack on the board and calling it a day. USB-C has the CC pins to indicate power availability, and I was considering going that route as an alternative. I've heard horror stories about bad USB-C cables, and I'm not 100% sure I understand the spec, but from
  7. I'm doing a revision of the hardware to add extra features and correct some bugs. @ronan also made good observations about things to fix, which is appreciated. Here's the list of what I'm working on: Move from KiCad 4 to KiCad 5, and change the footprints to match the awesome new library versions. Add USB for reprogramming & config updates (not sure if USB-C or just micro at this point, and I'm uncertain about powering via USB or leaving the barrel jack). Change the linear regulators to use more reasonable packaging, they're significantly oversized. Fix the oversi
  8. That's mostly how I figured it, assuming a 250mA load: (5-3.3) * 0.25 * 235 to get the 100C rise. The 250mA was just a ballpark figure, based on the max 180mA the ENC28J60 uses while transmitting plus a random amount extra; you'll probably want to run through what the max current consumption is for the various components to build a power budget and then add a bit extra for safety.
  9. I'd suggest swapping the MIC5319 for an alternative 3.3V regulator. SOT-23-5 won't be able to reject all that much heat; if you figure a max draw of ~250mA and a 5V input voltage (worst-case after the diodes), that's a ~100C temperature rise for that package. An alternative might be the MCP1825: it has minimal capacitor requirements, is available in SOT-223, and has a similar dropout voltage.
  10. I'm not very knowledgeable about the Mac driver side of the equation. There might be a hack to make the driver skip the gesalt check, but if there is I'm not aware of it. Another avenue might be to try the Focus drivers instead. From what I've read the Focus EtherLAN SC is basically just a rebranded Nuvolink SC, but I've never tried using their drivers on a scuznet board. I suspect they probably changed some stuff in the INQUIRY response to keep this from being easy.
  11. Oh, OK, I get where that's going now. I'd suggest not doing it that way; there are situations where you will need to read the data bus when C/D is not asserted. It would probably be easiest to assign it to a free I/O pin to maximize your control. Yes, they're specific to the 2.63V variant. Standard SCSI terminators are 110ohm, so that'd be the likely choice.
  12. I haven't had this ever happen to me, usually it just complains about the device not being present. What computer and OS are you running? I've been badly distracted by the (lame) real world but I did manage a quick pass through the schematic. I'm completely unqualified to look at the STM32 side of things, so the following are just observations on the SCSI / Ethernet parts. Like I've mentioned elsewhere in this thread, I'm no expert on this or anything, so definitely feel free to ignore the below advice without any concerns! All the driver chips are LS series in t
  13. Awesome, thanks to both of you for that information. I'll take a look and let you know if that did it.
  14. Great graphic, that's how I'd do it. Since the 245 is permanently reading from the bus you should be able to tie DIR without a problem. In case the bus floats for some reason (bad termination?) you might want to toggle /OE only when you know data is on the bus. The LVT transceivers have a 10ns/V transition time recommendation with "outputs enabled," so the current scuznet firmware does toggle /OE to avoid having the outputs on except when necessary, in case the SCSI bus is being sluggish during transitions. I don't know if this is strictly "needed" or not. For bus reading, the buff
  15. Thanks! The original design used the 574 with the latch clock hooked to /ATN, with the idea being to potentially fiddle with doing (slow) synchronous transfers; during periods when the board needed to read when /ATN was not active, an extra 74126 gate was used to block /ATN and let the microcontroller drive the latch. In the end, I felt like this caused more problems than it was worth, so I pulled the /ATN hookup from the released board but left the 574 there to minimize the disruption to the code. If I had to do it over again, I'd choose the 74LVT245 just to save an I/O
  16. Yay, awesome! Let me know if it causes any more grief, and glad I could help.
  17. All right, the most recent commits on Github have a much more comprehensive test suite ready to go. It requires building a simple loopback adapter for the DB25 connection, with instructions in the repo. At the moment, this will check all of the SCSI lines and the connection to the Ethernet controller, but not the memory card. Hopefully this will highlight whats going on if its a problem with the hardware.
  18. I've added a "testing" subdirectory to the Github repo that can be used to build a special firmware for doing post-assembly verification of a PCB. It's not comprehensive at all right now, but my goal is to expand it to cover as many of the connections into the microcontroller as possible. Boards like this have so many small parts that they are really annoying to debug if the hand-soldering is not perfect; I remember assembling some SCSI2SD clones a few years ago, and how much I appreciated having the scsi2sd-util helping me out when I had dry joints on some pads. @landoGriffin, I h
  19. Yeah, I agree that makes power issues seem way less likely. For the UART, 500kbaud is correct, but the device uses binary, not ASCII. Try that and see if data appears; debug.h has the symbol meanings. The LED will light during startup very briefly and again during bus transactions. Non-data transfers are fast enough it usually will just flicker briefly.
  20. I pushed an update to Github to help narrow down if this is a power problem. The Xmegas have a nice register that shows what the cause of the last reset was; I added a handler so if a reset was triggered by a brown-out the device will halt and go into a LED blink loop (1/2 sec on, 1/2 sec off). I figure a brown-out is a Bad Thing no matter what causes it, since it probably indicates the PSU is bad. If you could, try the most up to date firmware and let me know what you see. If you don't get the looping blink, could you let me know what state the LED is in when the system freezes?
  21. It should be 500kbaud, but it's mostly just symbols at certain code points. I should really get a proper debugger some time... Thinking about this more, I wonder if it might be a power problem: the Ethernet controller draws extra juice to transmit, and it might be enough to cause the MCU to do a brown-out reset if the USB power source isn't up to the task. I was thinking of adding an LED pattern on reset so you could see it, but if you tie into the debug line you should be able to observe a reset that way too.
  22. No, it should be working at the point you're at. I don't have the firmware in front of me, but as far as I can recall the weird INQUIRY response is normal. Basic bus transactions must still be fine to get the info from the Nuvolink utility, so I'm guessing it's not anything with your soldering. Are you using the most recent commit in the git repo, and did you compile with debugging enabled? I'll get my board out tonight and see if I can get some additional stuff added that might be helpful in figuring this out.
  23. Yeah, just in the documentation so people know not to connect external terminators. Apart from asserting /RST anytime another target tries to talk I doubt there is a way to force having just one device. If the transfer speeds are low you might be able to get away with some pretty nonstandard termination that wouldn't exceed the power budget. Maybe try something super simple, like 1K pull-ups to 3.3V? There are transmission line effects to consider, but that's black magic I have no experience with. AFAIK there were some Macs that had automatic termination supplied by the
  24. The STM32F103C8 is only rated to sink up to 150mA total across the device; even with only 1 active terminator on the bus that limit will probably be exceeded. It might be worth limiting the SCSI bus to just this one device and omit the terminator? Alternately, buffer chips driving the output lines would also fix the problem, but that'd obviously increase complexity and cost.
  25. The old school advice on tantalums was to derate by 50%, so maybe this is just an instance of failure from running too close to the margins, even from the factory? It might be worth going to 20 or 25V on the replacements.
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