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3.3v in & out of Prop, but no Prop found on any port — Parallax Forums

3.3v in & out of Prop, but no Prop found on any port

samartinjrsamartinjr Posts: 3
edited 2012-07-13 18:50 in Propeller 1
The Q44 Prop on by board has Ground going to all 4 VSS pins and the Brown Out Enable, 3.3v going to all 4 VDD pins, P28 & P29 going to EEPROM, P30 & P31 & RESn & Ground going to a propellor USB adapter, and nothing is touching the XO or XI pins. I'm getting 3.3v coming out of my unused prop pins, but when I connect my prop to the propellor tool via the mini-USB adapter it comes back saying it cannot locate a propellor on any port(Port 4).

When I move the USB cord over to my Demo board, it connects just fine through Port 3. I've gone into "Preferences" and watched as I disconnected the cable from the Demo board and reconnected it to my new board and seen "Port 3" disappear from the list and then Port 4 appear as I connected the cord to the new board, but the Prop Tool still says there is no Prop chip detected.

It's crossed my mind that the chip could be fried, but the fact that 3.3v comes out of the unused pins makes me second guess that.

Any thoughts or suggestions are greatly appreciated.

Comments

  • Phil Pilgrim (PhiPi)Phil Pilgrim (PhiPi) Posts: 23,514
    edited 2012-07-13 01:05
    Are you sure you don't have P30 and P31 reversed? P31 is the input from the USB adapter to the Prop; P30 is the output from the Prop to the adapter.

    -Phil
  • samartinjrsamartinjr Posts: 3
    edited 2012-07-13 01:14
    I tried it both ways
  • Mark_TMark_T Posts: 1,981
    edited 2012-07-13 02:07
    Decoupling adequate? short between pins (particularly 28..31)?
  • samartinjrsamartinjr Posts: 3
    edited 2012-07-13 03:01
    I checked continuities on all pins of the USB chip. There's no continuity across any of the pins while the cable is disconnected. With the cable connected a couple of the pins do short.
  • RaymanRayman Posts: 14,826
    edited 2012-07-13 03:27
    Yeah, I think 3.3 V coming out of unused Prop pins is definitely not a good sign...

    I've never seen a Prop fail that way though, so my guess is that there's a wiring problem somewhere...

    You might want to triple-check that you have Vdd and Gnd on the right pins...
  • N8VHFBrianN8VHFBrian Posts: 2
    edited 2012-07-13 18:50
    I have a couple of questions ....
    Is this a board you designed and built?
    If yes, do you have one of the FTDI USB to serial chips built into the board?

    If the answer is yes to both questions you may need to download the FProg utility from FTDI and configure the USB to Serial chip.
    I recently built a board with an onboard usb to serial and had to set the invert TX/RX signals before it would work.

    -Brian
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