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About pzw

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  1. Might seem unrelated to you... But what kind of power supply are you using? You need a good power supply which can easily supply high currents (2A). A standard phone charger will not work reliably. Also the quality of the SD card is very important. Samsung EVO cards have always worked great for me. FYI My 2E has been running Armbian mainline for the last 12 weeks non-stop, with a EVO 32GB card and a 5A PSU, which is also supplying some other power hungry stuff, but has for sure enough capacity for the 2E... No problems at all stability wise!
  2. You use different clock speeds between the Arduino and the OPi. Depending on the wiring parasitic capacitance, this can make the difference.... Also... Are you running the Arduino on 5V or 3.3V? I guess 3.3V since the LDC1314 is a 3.3V device.. But just making sure :-) . What surprises me is by looking at the scope images is that it seems that the SDA line is held at 1/2Vcc . You say that doesn't change depending on the pull up resistor value. And that is strange. Because that means it is a state which is voltage controlled, and not the result of a "latched up" driver or something. Because if that would be the case, the voltage would move depending on the pull up resistor. The driving element will be having the same resistance in the latched state... Just thinking out loud now...
  3. If the "0" level is not hitting ground, it means that the current through the switching device (BJT/FET etc) is too high. A pullup of 4k7 seems to be ok, but I am not 100% sure if there is a pull up on the die of the CPU... So I would personally start with removing the pullups... Or... You have a bad ground connection. Can you take a picture of the wiring?
  4. pzw

    NanoPI Duo availability

    What changes will be implemented?
  5. pzw

    NanoPI Duo availability

    I tried asking FA, but didn't get a reply... I need a few for a project which has only space for that module... (got 36mm width to use....) Every week I try to check it, but so far no luck. I am wondering if it would help to just order a few so I might get them sooner..
  6. pzw

    TTL to RS232 possible?

    The converters which were "faked" were the FTDI based USB <--> RS232 converters... The converter you are using is based on a Sipex 3232 (or Maxim MAX3232) chip. Those are so super basic converters (you can buy them on a PCB ready to go for 15 cents each!) that they are not worthwhile faking... I bet you that the issue you are having is just a cold (bad) solder joint, like in the picture below... The sad part is that this is a picture of an advertisement of one of those 15 cent converters ads on Aliexpress.... In this case the converter would actually work, since the cap with the bad connection is the power supply bypass... So their "quality control" would not even notice it in a functional test..
  7. @TonyMac32 Thanks for verifying it :-) . It did strike me as odd if FA would have overlooked this termination requirement... Also I would have expected network throughput issues because of it, but I couldn't find reports about that... So that made it almost certain that the termination was happening on the die.
  8. @chwe In the schematics it was not clear if there is a termination circuit inside the CPU... The headache referred to the required implementation of a termination circuit in my design.
  9. Great news! Thanks @guidol. Saves me a headache.. haha .. I suspected that the termination might be in the h2+ ... Thanks for confirming this..
  10. Thanks @guidol! Last question. Was that powered up?
  11. No termination there...😐🤨
  12. @chwe the snippets in my post come from their diagram of the module... I noticed forgot to add the snippets from the shield.. I'll add it when I'm home again. But that will show no termination circuit...
  13. I have one more question, which I hope @guidol can help with too... If I read the datasheet of "magjacks" made by Pulse (that is a connector with built in transformers / magnetics) I see the following; There is clearly an set of resistors terminating the lines from the magjack to the PHY (in the H2+)... However on the diagrams there is nothing like this; So I hope that someone can measure for me the resistance between pin 13&14 on the headers of the DUO when it is not plugged into a shield. If there is a resistance of about 100ohms, it means that these resistors are built into the CPU... If not, then I need to add them. (And FriendlyArm might need to revise their shield or module ;-) ) Thanks in advance!
  14. Great! That's all the information I was looking for! Thanks a lot @guidol
  15. I'm currently designing a PCB which will use a nanopi duo board. Unfortunately it is not in stock at the moment so I can't order one yet to verify some measurements. Can someone (@guidol or @larry bank maybe?) who has one sitting on their desk please give me the following info; - Distance between headers. Total width is 1" so I guessed 0.9"... Is this correct? - length of the pin headers. So I know how high it will sit on the PCB - total height of the pins + PCB - is there anything on the bottom PCB which is higher than the plastic on the pin headers? In other words; can I push the whole module all the way down to a PCB and then only have the thickness of the plastic of the pin headers? Or is something "sticking" out.. - How much does the heatsink add to the total thickness? (Or what is the thickness of the heatsink...) Thanks in advance for your help and time.