Shop OBEX P1 Docs P2 Docs Learn Events
DLP-TXRX-G with propeller — Parallax Forums

DLP-TXRX-G with propeller

gilabitegilabite Posts: 20
edited 2008-12-04 02:31 in Propeller 1
Hello, I just recently got a DLP-TXRX-G for free and was hoping to make it work with my Propeller but I am having problems.· I'm thinking it has to do with the DLP's DTR, pin 4. Here is the DLP's datasheet (it kinda sucks) URL http://www.dlpdesign.com/usb/dlptxrx-v14-ds.pdf·. I was wondering if anybody has any experience with these or can help in anyway. Thanks.

Comments

  • parts-man73parts-man73 Posts: 830
    edited 2008-11-27 00:58
    Looks pretty straight forward, although a completely different pinout from the PropPlug.

    Are you planning to connect to a protoboard? or a Propeller on a solderless Breadboard?

    If connecting directly to a DIP Propeller
    • DLP pin 1 TX
      > Propeller pin 40 (P31)
    • DLP pin 2 RX
      > Propeller Pin 39 (P30)
    • DLP pin 3 VSS
      > VSS on breadboard (pins 9 and 29 on Propeller)
    • DLP pin 4 DTR
      > Propeller pin 11 (reset)

    This *should* work - I don't see a cap in the DTR circuit to stretch the DTR pulse, but I think it will work as is.

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    Brian

    uController.com - home of SpinStudio - the modular Development system for the Propeller

    PropNIC - Add ethernet ability to your Propeller! PropJoy - Plug in a joystick and play some games!

    SD card Adapter - mass storage for the masses Audio/Video adapter add composite video and sound to your Proto Board
  • DufferDuffer Posts: 374
    edited 2008-11-27 01:12
    From the markings on the board itself, it looks like it ought to be (top to bottom):

    Tx, Rx, GND, Reset, Vcc

    It's not the same pinout as that PropPlug, but the signals are there and it appears to use the same FTDI chip, so the drivers installed with the Propeller Tool should work. It also provides either 5V or 3V, selectable with a "solder bridge" rolleyes.gif .

    Duffer
  • gilabitegilabite Posts: 20
    edited 2008-11-27 01:13
    Thanks for the reply. I have it on a breadboard with the Propeller.·The way you show is how I have it hooked up but I·dont get any response from the·Propeller. When·I have the Propeller tool try to identify hardware·the·TX light on the DLP blinks once but I get nothing back from the Propeller (the RX light·dont blink). There is nothing wrong with the·Propeller or my setup, as soon as I disconnect the DLP and go back to my serial setup the Propeller is recognized just fine.··
  • gilabitegilabite Posts: 20
    edited 2008-11-27 01:15
    Yeah I didnt like the solder bridge either (to cheap for a jumper). I havent messed with pin 5 because of the solder bridge and because I didnt think I needed to.
  • gilabitegilabite Posts: 20
    edited 2008-11-27 02:46
    Yeah I really think it has to do with the DLP's DTR pin not having the cap there. Parts-man73 do you think adding it between the DLP and the Propeller's pin 11 would work? If so would I need to add the 10k resistor to ground (as shown in the schematic for Parallax's prop plug) also? Thanks for the help.
  • parts-man73parts-man73 Posts: 830
    edited 2008-11-27 03:23
    gilabite said...
    Parts-man73 do you think adding it between the DLP and the Propeller's pin 11 would work?

    It certainly wouldn't hurt anything to try
    gilabite said...
    If so would I need to add the 10k resistor to ground (as shown in the schematic for Parallax's prop plug) also?

    I just refered to the PropPlug schematic, I don't see the 10k resistor to VSS that you are refering to. On the DLP design, I see now that there is a 10K resistor between the FTDI chip and the base of the transistor. whereas the Parallax design pulls this low with a 33K resistor. This may be the difference in circuits that is causing the propeller not to get the proper reset pulse, and thus not entering programming mode.

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    Brian

    uController.com - home of SpinStudio - the modular Development system for the Propeller

    PropNIC - Add ethernet ability to your Propeller! PropJoy - Plug in a joystick and play some games!

    SD card Adapter - mass storage for the masses Audio/Video adapter add composite video and sound to your Proto Board
  • gilabitegilabite Posts: 20
    edited 2008-11-27 03:35
    Ah ok my bad its not the prop plug schematic, its the Propller demo board's onboard USB to serial schematic. It shows the DTR pin from the FT232R going through a 10nf cap then it branches to the transistor in one direction and in the other goes to the 10k resistor I was referring to then to VSS. If it is the difference of the resistors (the 10k on the DLP vs. the 33k on the prop plug) do you have any ideas on what I can do to make it work? Oh and by the way your spin studio kicks ***, Ive only got part of it so far but planning on getting the rest when I have the funds for it.
  • parts-man73parts-man73 Posts: 830
    edited 2008-11-27 03:58
    gilabite said...
    It shows the DTR pin from the FT232R going through a 10nf cap then it branches to the transistor in one direction and in the other goes to the 10k resistor I was referring to then to VSS.

    That resistor is there to pull that section of the circuit low when the DTR signal is not actively driven. I'm not sure why the DLP design omits it. I can't think of a good way to add that to their circuit board either confused.gif But maybe this is an error in the documentation, and not an error in the actual product.


    gilabite said...
    Oh and by the way your spin studio kicks (censored),
    Thank you! I hate to follow a compliment with a admonishment, but vulgarity is normally frowned upon in these forums.

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    Brian

    uController.com - home of SpinStudio - the modular Development system for the Propeller

    PropNIC - Add ethernet ability to your Propeller! PropJoy - Plug in a joystick and play some games!

    SD card Adapter - mass storage for the masses Audio/Video adapter add composite video and sound to your Proto Board
  • gilabitegilabite Posts: 20
    edited 2008-11-27 04:06
    I apologize for my vulgarity, I figured if it let me post it was ok, it was my natural response. But anyway I tried adding the cap between the DLP and the Propeller's pin 11 with no luck so that makes me think it is the resistor that you are talking about. Thanks for taking the time to help out, hopefully someone will have some ideas on what can be done.
  • gilabitegilabite Posts: 20
    edited 2008-12-04 02:31
    Ok so I figured out why it wasnt working. I finally had time to bust out the scope and see what the DTR pin of the DLP was doing. It was staying at 0 volts and·then going to 3.3 volts·for the programming signal, the opposite of what the propeller needs. So I opened up Mprog and reprogrammed the DLP to invert the DTR signal and voila, it works fine. I figured I would post how I fixed it for anyone else that may need to.·Thanks for the help everyone.
Sign In or Register to comment.