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Thread: DSATX + brainstem problem

  1. #1
    Join Date
    Oct 2008

    Unhappy DSATX + brainstem problem


    I purchased a DSATX 220 + optional brainstem with the intention of logging power draw and battery voltage live from within my carputer itself, but have so far been unable to get the DSATX to behave when the brainstem is plugged in and connected to anything.

    With the brainstem disconnected or connected to the board but not connected to a computer, everything is dandy; caomputer boots up on start of car, and shuts down cleanly on shutdown, couple minutes after that load goes off, just as advertised

    HOWEVER, when I attempt to use the brainstem for logging (or any other purpose), the computer won't even boot up at all. Here's a quick rundown of what happens when I have the brainstem plugged in.

    1> Ignition turned, VAcc goes high
    2> Debug output begins scrolling on my terminal session
    3> 5V Standby power comes online, I see LED on mobo light up
    4> PWR signal passed to mobo; CPU/case fans kick in
    5> Fans start to "stutter", it looks as though power is rapidly cycling on and off at this point, no POST beep is heard and LED mobo dims/turns off
    6> Debug output continues flowing; shows no issues, Load is well below max on all rails
    7> After a few seconds of this, load is dropped entirely by the PSU; Fans and mobo LED go dead; this is verified by the debug output, which shows close to zero amps on all rails
    8> Debug output ceases after around 3-4 seconds of this

    Total time is less than 10-15 seconds; I can provide a console trace from one of these sessions after I get home today.

    Things I have tried:
    Shorting A2 and B2: Simply cause the above to repeat ad infinitum
    Using the serial interface to reset to default values
    Using the serial interface to program extended basic options
    Using the serial interface to revert to using POTS

    The only thing that seems to help is not utilising the brainstem; whcih kind of sucks because that's one of the reasons I got this particular PSU

  2. #2
    Join Date
    Oct 2008
    To follow up a little; i think i found the issue; I'm using a usb-serial converter, and apparently, merely plugging or unplugging the serial end of the device into the brainstem also has the effect of "hiccuping" the DSATX, just as plugging the brainstem itself in does; causing it to reboot the DSATX microcontroller (Grounding issue maybe? One wouldn't think so as the usb, mobo, and DSATX should share a common ground, but maybe the innards of the USB-Serial dongle has some bizarre wiring...)

    In my case, I had a usb-serial cable connected from the carputer mobo into the DSATX; when I turned the ignition, the DSATX would assert PS_ON and power up the mobo, which then immediately powers up its USB devices. Once the USB-serial adapter gets juiced up, it hiccups the DSATX, causing it to reboot and drop the power; the USB-serial device then powers down, and hiccups the device yet again. Now, since Vacc is already high, the DSATX almost instantly asserts PS_ON after coming back up, and the cycle repeats, until the DSATX just gives up entirely at some point.

    From the serial console you can't really tell it's power-cycling because the micro-controller comes back up almost instantly, and just prints another status message to the screen, which is exactly what would happen had it not rebooted.

    So, my next course of action is to try a plain serial connector, as I happen to have a spare serial header on the motherboard, to see if it exhibits the same behaviour. In the meantime, does anyone know if this is the correct behaviour for the DSATX?

    Edit: looks like a couple other people have had similar issues with the brainstem; anyone out there using the USB brainstem; any better/worse than the serial?

  3. #3
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    MarcelP's Avatar
    Join Date
    Nov 2007
    Hey, i have the same Issue.

    But i have this fixed by different (self-made) com2usb-adapter-cable!!

    Look here:
    My Project: German/English

  4. #4
    Join Date
    Oct 2008
    Quote Originally Posted by MarcelP View Post
    Hey, i have the same Issue.

    But i have this fixed by different (self-made) com2usb-adapter-cable!!

    Look here:
    Thanks for the info; I've now tried a direct connection from the serial header on the mobo to the brainstem, with the same effect. I'll give your solution a shot next before giving up on this...

  5. #5
    Maximum Bitrate
    Join Date
    Apr 2006
    Sydney, Australia
    Hi, I too am having a comms problem with my DSATX + brainstem.

    I'm trying to update the firmware, but no luck. Both YEL & RED leds are on, on the brainstem, but when I use the megaload app V7 to update FW it fails and it fails even after several attemps in shorting A2 and B2.

    If I use HyperTerminal @ 9600, i get echo back and if I enter "E" i get enable writing. So this proves I'm talking to the PSU via the brainstem.

    With the Megaload app, it recommends 115kbps.

    Any ideas?

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