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Is There a Way to Keep Propeller from Resetting When Connecting with USB? — Parallax Forums

Is There a Way to Keep Propeller from Resetting When Connecting with USB?

Duane DegnDuane Degn Posts: 10,588
edited 2014-04-26 19:51 in Propeller 1
I'm aware of the problem many Propeller boards with on board USB have with resetting when not connected to a PC. To overcome this I used this software solution Beau posted.

Another problem is the reset when the Propeller connects with a PC. I haven't been able to find a software solution for this issue.

I appears the easiest solution to the USB reset issue is to add a jumper or switch to the reset line. The boards for this project have already been made and I'm pretty sure my client doesn't want to add a switch or jumper.

The boards will need to have their programs updated occasionally so removing the reset circuitry also isn't a desirable option.

Are we stuck with having the board reset when connecting to USB without some sort of hardware change?

Here's a link to a thread where someone asked this same question (without resolution).

Comments

  • Duane DegnDuane Degn Posts: 10,588
    edited 2014-04-08 11:53
    Duane Degn wrote: »
    Are we stuck with having the board reset when connecting to USB without some sort of hardware change?

    I take it that's a "yes"?

    Is there a setting within the FTDI chip that would keep the reset line from being toggled when the Prop board is being connected via USB?
  • jazzedjazzed Posts: 11,803
    edited 2014-04-08 12:00
    Duane Degn wrote: »
    I take it that's a "yes"?

    Is there a setting within the FTDI chip that would keep the reset line from being toggled when the Prop board is being connected via USB?

    Afraid so.

    There doesn't appear to be any setting to control DTR behavior from the FTProg tool except for inverting the sense of the signal.
  • Beau SchwabeBeau Schwabe Posts: 6,566
    edited 2014-04-08 12:10
    In the MS-DOS days and early Windows days you could set the DTR to any state from the PC side. You can still do it now but it's a little more involved. I'm pretty sure Visual Basic can do it with the right serial drivers.
  • RaymanRayman Posts: 14,659
    edited 2014-04-08 12:47
    Well, for PKS, I connected the reset transistor to the Prop through a 100 Ohm resistor.
    Then, I connected a Prop Pin to the reset input of the Prop.

    So, when that pin is programmatically sent high, the Prop cannot be reset by the FTDI chip.
  • Duane DegnDuane Degn Posts: 10,588
    edited 2014-04-08 12:48
    Thanks guys. I was afraid there wouldn't be an easy fix.

    My client is using some sort of interface created with LabView. I'll ask if there's a way for the interface program to control the DTR state. I'm inclined to think there isn't.

    The reset hasn't ever been an issue in my personal projects so I hadn't worried about it before.
  • Duane DegnDuane Degn Posts: 10,588
    edited 2014-04-08 12:49
    Rayman wrote: »
    Well, for PKS, I connected the reset transistor to the Prop through a 100 Ohm resistor.
    Then, I connected a Prop Pin to the reset input of the Prop.

    So, when that pin is programmatically sent high, the Prop cannot be reset by the FTDI chip.

    I like this idea. I'll probably use it in future boards.

    Thanks.
  • tonyp12tonyp12 Posts: 1,951
    edited 2014-04-08 13:04
    Yes having a Prop pin as output with a high or low state to override any DTR signal using some resistors
    and when it's time to reprogram a power reset gives you 4 seconds to click send in prop-tool
    as your program have not yet set the pin from the default input after a hardware re-boot.

    My choice would be to force a state on the Transistor Base.
  • DurbanFlyBoyDurbanFlyBoy Posts: 7
    edited 2014-04-26 19:34
    Morning guys
    Try changing the value of the shunt capacitor for the reset. Originally I had this constant resetting of the propeller if there was no USB connection, and this was not good in the one project I did to control a high-power hydro-turbine that ran-away in 5 seconds if the load is lost while the propeller is incapacitated due to this irritating problem. I think in the original cct from Parallax, the value was 10nF, I changed this to 100nF, and the problem with constant resetis solved when there is no USB connection. However, the board will reset on connection, due to the behaviour of DTR.

    Best regards from Thailand!

    Allan
  • DurbanFlyBoyDurbanFlyBoy Posts: 7
    edited 2014-04-26 19:42
    And here is a real solution from the Parallax boys....

    http://forums.parallax.com/showthread.php?135067-Serial-Quirk&p=1043169&viewfull=1#post1043169

    Best regards
  • Duane DegnDuane Degn Posts: 10,588
    edited 2014-04-26 19:51
    DurbanFlyBoy wrote: »
    And here is a real solution from the Parallax boys....

    http://forums.parallax.com/showthread.php?135067-Serial-Quirk&p=1043169&viewfull=1#post1043169

    Best regards

    Allan, Are you aware that's the same link as the first link in post #1 of this thread?

    The only working solution to keep a Propeller board from resetting when connecting to USB is to have either a switch to disconnect the reset line or to use a Propeller I/O pin to hold the reset line in a constant state.
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