P2-ES Board Support

124»

Comments

  • VonSzarvas wrote: »
    Thanks, that helps diagnose.

    Sounds like the left side usb power switch has half-blown, or the diode mod next to it needs some rework.

    Either way they'll need a lab fix. If thats something you'd want to do, I could share instructions. Otherwise, best to contact Parallax support and see about returning it for diagnosis. I'll send a headsup to the engineer that'll handle it.

    Send me the instructions anyway. I'll have a look and decide if I want to dig in that far or send it in.
  • Most likely it's the Zener or IC in this area will need replacement, or to check for bad joint or shorted joint.

    Schematic here: https://www.parallax.com/downloads/propeller-2-es-eval-board-schematic

    The IC is U501 on the schematic, Diodes Inc : AP22802AW5-7

    The other 2 parts will look different on your board, as there was a mod made at that place. And that might be what has failed.
    Pretty small parts- you might need a decent magnifier to inspect and probe them :)

    The Zener is D504 on the schematic, 3V zener voltage, ON Semi : MM3Z3V0ST1G
    That Zener has a 10K pulldown resistor. And there's a tiny cap under there too.

    As you get 2V or so, my hunch would be the Zener is not doing it's job, and the U501 is half-switching on when it shouldn't be. If you pulled a high current load when you measure 2V, you'd probably smoke the U501. But that seems not yet to have happened based on your readings, so I'd look for signs of an issue with the mod first.

    Hope that helps a bit.


    758 x 480 - 525K
  • VonSzarvas:

    Thanks!

    I think that is beyond my eyesight.
    I will contact Support and proceed that way.



  • My P2_ES board appears to be suffering the same issue. :(
    Trying to power the board from the P2-USB socket drags 5V down to 0.5V.
    Board works fine from PC-USB but needs boosting as 5V is loaded down to 4.7V

    Melbourne, Australia
  • ozpropdev wrote: »
    My P2_ES board appears to be suffering the same issue. :(
    Trying to power the board from the P2-USB socket drags 5V down to 0.5V.
    Board works fine from PC-USB but needs boosting as 5V is loaded down to 4.7V

    This sounds like the same trouble Evanh's P2 Eval board developed.
  • Ozpropdev, do you know what is drawing such excessive current?
  • Not sure exactly Chip.
    Running at 180MHz with garryj's USB mass storage driver and a custom version of my P2 logic analyzer.

    I removed all accessory boards (VGA & USB), made no difference.
    I'll keep digging...
    Melbourne, Australia
  • I suspect that the power switching circuitry is causing a current draw.
  • Mine only behaved that way when a certain dead VIO pin on the prop2 was jumpered to the VIO switchmode supply. The switchmode started whining and drawing lots of current. Take that jumper off and current draw went back to normal.
    "We suspect that ALMA will allow us to observe this rare form of CO in many other discs.
    By doing that, we can more accurately measure their mass, and determine whether
    scientists have systematically been underestimating how much matter they contain."
  • VonSzarvasVonSzarvas Posts: 1,658
    edited 2019-02-10 - 13:03:34
    cgracey wrote: »
    Ozpropdev, do you know what is drawing such excessive current?

    @ozpropdev

    This seems similar, but could be slightly different to the issue DaveJenson reported above.

    Has this problem just started? (Not sure when you got your board- if this was working before...?)


    Are you able to read the FTDI settings, and confirm that CBUS is configured to "PWREN#" ?


    If that setting is good, then either U501 (AP22802AW5-7) has blown, or the mod components have failed
    I'd start by metering the connections around the mod to ensure there's no short between the zener anode and gnd (should be 10k).


    One other thing... is there any difference in behaviour if you connect either supply only (from power off state), vs connecting one supply first, then adding the other? In terms of 5V level and the ON-LEDs behaviour.




    Here's that part of the schematic, including the mod parts D504 and R507.


    1586 x 1632 - 87K
  • OzProp brought his board over

    1. His board is still working fine when in normal "PC USB" (via ftdi) supply mode
    2. When AUX power is added, the 5v as measured on header pin drops to around 72mV
    3. FT_PROG shows same for his and mine, specifically PWREN# on C2 and C3 of FTDI
    4. My anode reads 10040 ohms to ground, his 9560 ohms
    5. Just powering from AUX side only results in 0V on the 5v header, rather than 72mV
    6. We noticed, when powering from PC USB (ftdi chip side), the 5v header reads 72mV until enumeration takes place, at which time it jumps to 4.97v

  • Digging a bit deeper, I'm pretty sure its the Aux 22802 switch that has failed. Despite the slight differences on 10k nominal, the EN pin of the 22802 is still getting 2.82v on OzProp's board, vs 2.88v on mine, both well above the 1.5v threshold on the datasheet.

    Looking at the other end of the zener shows 4.91 v from the AUX USB, and we know there isn't something permanently loading the 5v Common because its fine when PC USB supplies power.

    I can't think of what else it can be other than that 22802 switch. Doesn't look too hard to replace, we just need to understand the 'stack up' of the mod, because I'd just replace everything in that corner
  • evanhevanh Posts: 8,057
    edited 2019-02-11 - 01:55:42
    EDIT: Oops, I misunderstood what you meant by 5v header.
    "We suspect that ALMA will allow us to observe this rare form of CO in many other discs.
    By doing that, we can more accurately measure their mass, and determine whether
    scientists have systematically been underestimating how much matter they contain."
  • roglohrogloh Posts: 1,439
    edited 2019-02-11 - 03:43:52
    @Tubular ,
    Perhaps the anode of the Zener mod is not making good connection with the EN pin of the USB switch leaving it floating. Is it worth resoldering that joint before replacing the entire switch or mod? Data sheet says not to leave EN pin floating. I'm wondering if that 22802 is actually off all the time. When powered by AUX-USB port is the 5V rail even able to supply any current at the 0.5V level indicated? Maybe that 0.5V is from some other leakage/diode protection path.

    UPDATE: just re-read your post Tubular. If you've already probed directly at the U501 EN pin rather than the solder blob ignore what I have said. Looking at my own board the mod joint looks like a Y where the three components meet and I was thinking you could potentially probe part of it that didn't reach the EN pin if you didn't touch it in the right place.
  • TubularTubular Posts: 3,723
    edited 2019-02-11 - 05:43:38
    We've been probing directly on top of that stack, but you're right, its worth resoldering that joint to be sure.

    (edit: I checked under a scope, its a really solid soldering connection at that EN junction. No chance contact wasn't being made, but a good suggestion nonetheless)
  • Tubular wrote: »
    OzProp brought his board over

    1. His board is still working fine when in normal "PC USB" (via ftdi) supply mode
    2. When AUX power is added, the 5v as measured on header pin drops to around 72mV
    3. FT_PROG shows same for his and mine, specifically PWREN# on C2 and C3 of FTDI
    4. My anode reads 10040 ohms to ground, his 9560 ohms
    5. Just powering from AUX side only results in 0V on the 5v header, rather than 72mV
    6. We noticed, when powering from PC USB (ftdi chip side), the 5v header reads 72mV until enumeration takes place, at which time it jumps to 4.97v

    Thanks for doing all this Tubular.

    3. Correct.
    4. Probably 5% resistor. That's fine. Anything above 1K reasonable. The diode pMax is 300mW.
    5. Interesting. The USB switch is fully off. Could be the output discharge of the USB switch is activating when you apply current to the OUT pin, pulling down the rail. That's only supposed to trigger for a couple msecs, but with something blown internally could be failing to perform as expected.
    6. Correct. PWREN will only enable the USB switch after enumeration.


    Here's the mod diagram you asked about.

    AFAIK, the actual mod used 10k in-place of the 3k9 shown in this diagram. It's not critical, provided it keeps the diode power within specification when VIN is 6V.
    The unmarked 0402 part that the 3k9 (10k) connects to is a cap. Anything 0402 size 1uF or more is fine here.
    The red X on the R507 doesn't mean cut. Just remove that part.

    1757 x 1143 - 178K
  • Great, thanks von Szarvas. We'll order some spares towards the end of the week, just in case.

  • Hi everyone -

    Is there any estimated timeline on a future p2 board? I'd love to play around with the p2...

    Frank.
  • Next batch of P2 chips are due in May. There will be an Eval board available pretty soon after those chips arrive. Look out for announcements here early May.
  • Thank you! I'll check back in May!
  • Is there a .dxf of the board available?
    Prop Info and Apps: http://www.rayslogic.com/
  • VonSzarvas wrote: »
    Next batch of P2 chips are due in May. There will be an Eval board available pretty soon after those chips arrive. Look out for announcements here early May.
    Awesome, it’s now early May. Any announcements pending? :-)

  • "We suspect that ALMA will allow us to observe this rare form of CO in many other discs.
    By doing that, we can more accurately measure their mass, and determine whether
    scientists have systematically been underestimating how much matter they contain."
  • Is there any kind of "Getting Started" guide for the Propeller 2 ES Evaluation Board ?

    Bean
  • No Getting Started guide yet, but the Product Guide does give some detail about each of its features. Commenting is enabled, and we invite your feedback.
Sign In or Register to comment.