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use FDTI friend instead of propeller plug — Parallax Forums

use FDTI friend instead of propeller plug

lee oswaldlee oswald Posts: 11
edited 2011-02-15 12:16 in General Discussion
could someone tell me how to use FDTI friend, in place of the
propeller plug, and if is safe to use.
since FDTI friend has 6 pins and not have the RST pin.
grateful for any help.

Comments

  • Mike GreenMike Green Posts: 23,101
    edited 2011-02-14 17:40
    What's an "FTDI friend"? Can you provide a link to the manual or datasheet?

    The Propeller needs 3.3V logic Transmit and Receive signals plus ground plus a "switch closure" to ground for reset, usually furnished by a switching transistor when DTR goes from false to true (with a capacitor in series with the DTR signal). Look at the PropPlug circuit or the circuit for the USB Protoboard for an example.
  • schillschill Posts: 741
    edited 2011-02-14 19:57
    I expect this is what Lee's talking about:

    http://www.ladyada.net/learn/breakoutplus/ftdifriend.html
  • LoopyBytelooseLoopyByteloose Posts: 12,537
    edited 2011-02-15 00:17
    There are many alternatives to using a Propeller Plug, but you need to have an equivalent to a RST pin via the DTR signal as well as the Transmit and Recieve. Some do provide this, and others don't. Sometimes, it is the chip that actually is lacking the RST ability, and at other times it is the software driver. And everything need 3.3 volt logic, meaning that 5 volt logic is a hazard.

    At the end of the day, it is up to the buyer of alternatives to become aware of the engineering involved. If you buy the Propeller Plug, you just use it without the additional hassle.

    I have another brand of AVR programmer that offers TTL RS233 and it appears to be useful for programming the Propeller, but I've never tried as I've enough other projects to think about and build. This is just another hack that can be done, if you wish to pursue it.
  • electrosyselectrosys Posts: 212
    edited 2011-02-15 00:47
    FTDI Friend, is a breakout board of FT232 chip, the same chip that Parallax use at the PropPlug, so you can use it as Mike explain it and you can also have a look at the PropPlug circuit or the USB protoboard for an example circuit.

    Prop Plug:
    http://www.parallax.com/Portals/0/Downloads/docs/prod/prop/32200-32201-PropClipPlug-v1.3.pdf
  • lee oswaldlee oswald Posts: 11
    edited 2011-02-15 01:32
    Mike,
    I have only one propeller plug that I use a lot.
    I also have a FDTIfriend who I bought on adafruit for another purpose.
    see below the url (from schill).

    http://www.ladyada.net/learn/breakoutplus/ftdifriend.html

    I started thinking that yesterday, i should have already an alternative
    beyond that.
    look good,
    the value USP is high and for my to buy only one propeller plug,
    I can not speak here in the company to make a request just 1 propeller plug.
    and if something happen ?.
  • Martin_HMartin_H Posts: 4,051
    edited 2011-02-15 05:06
    Since I program Arduinos and the Propeller I use a Wulfden USB-BUB with Brian's BUB2Prop adapter (http://www.wulfden.org/TheShoppe/pa/index.shtml). It might work with FTDI friend as long as the voltage levels are compatible. The USB-BUB contains a jumper to switch between 3.3 and 5 volt mode, but the AVR sees 3.3 as logical 1, so I leave it in that mode.
  • Paul MPaul M Posts: 95
    edited 2011-02-15 05:32
    I use the FTDI wire ended (-WE) 3v3 cables (http://www.ftdichip.com/Products/Cables/USBTTLSerial.htm), in fact I don't even own a propplug.
    Note that the FTDI cable does not provide a DTR line but fortunately the propeller tool allows one to use the RTS signal instead; see the 'Operation' tab in the <edit><preferences> menu in the Propeller tool.

    I also use these cables for general serial comms on some projects and use a multipole connector other than a standard usb connector.
  • HollyMinkowskiHollyMinkowski Posts: 1,398
    edited 2011-02-15 10:23
    Since it is easy to do USB on a Tiny25 (VUSB) I wonder if
    that uc could be fashioned into a super cheap replacement
    for a prop plug? Perhaps zeners could handle the drop to
    3.3 level somehow?

    The Tiny25 does not even need a crystal to do USB1.1 because
    you can have the programmable internal rc timer auto adjust to
    work with the USB port.
  • PropabilityPropability Posts: 142
    edited 2011-02-15 11:08
    I've seen many times referenced where using a 5 volt usb to ser converter for doing anything with the prop would do "harm" because of the props 3.3V nature . I would agree but I find it kind of odd that if you look at the prop proto board non usb #32212 you will see in the schematics that there is a provision for using parallax's usb2ser #28024 (a 5 volt design) with a direct connection with no current limiting resistors.
  • schillschill Posts: 741
    edited 2011-02-15 11:20
    Propability wrote: »
    I've seen many times referenced where using a 5 volt usb to ser converter for doing anything with the prop would do "harm" because of the props 3.3V nature . I would agree but I find it kind of odd that if you look at the prop proto board non usb #32212 you will see in the schematics that there is a provision for using parallax's usb2ser #28024 (a 5 volt design) with a direct connection with no current limiting resistors.

    There are 150ohm resistors inline with tx and rx on the usb2ser itself.

    The FT232RQ can be reconfigured to have 3.3 IOs, but that would require modifications to the usb2ser.
  • lee oswaldlee oswald Posts: 11
    edited 2011-02-15 12:16
    works fine,

    VSS, TX, RX from pins 1,5,6 of FDTI.
    RST as was said by professionals, comes from the DTR signal, after passing through a 10nF capacitor, and the cheapest NPN transistor, standing before a pull down resistor (33k).
    thanks for the help.
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