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BS2 usb to serial adapter question — Parallax Forums

BS2 usb to serial adapter question

yousefyousef Posts: 21
in BASIC Stamp
Hi,
I am trying to program the basic stamp 2 module using this usb to  serial adapter :https://www.pololu.com/product/391 I connected the RTS to DSR, TX to SIN, RX to SOUT. And I connected DTR to ATN through a capacitor. when I try to program it, the module is not identified. there is a loopback and echo, but no basic stamp found. the basic stamp is a new one and working properly with Parallax USB to Serial Adapter. I even tried sparkfun FTDI basic breakout board, but still didn't work. it only works with parallax's adapter.
is there a special connection that I must do in order for these adapters to work?
thank you

Comments

  • Hal AlbachHal Albach Posts: 747
    If you look at the schematics for the basic stamp boards that are USB, you will notice that several signals from the USB FTDI chip are inverted before hitting the stamp.  Also, since you have mentioned connecting all the various signals, did you tie the stamp ground to the interface ground? That is overlooked at times by other people.
  • yousefyousef Posts: 21
    yes the ground is connected. I also tried those schematics but still not working.
  • ercoerco Posts: 20,254
    That looks to be a Silabs 2102 chip.  Rx and Tx (not sure about RTS) will need to have signals inverted to talk to a Stamp, along the lines of the attachment. When in doubt go with a Parallax FTDI adapter.
    2102adapter.jpg
    852 x 501 - 72K
  • Hal AlbachHal Albach Posts: 747
    Just noticed this rather prominent note on the Pololu web page you linked.
    Note: This product does not include printed documentation or software discs. The Pololu USB-to-serial adapter requires software drivers to operate; please see the resources tab for more information. 

    Have you installed the required driver as indicated?
  • yousefyousef Posts: 21
    I did install the driver. I will try again to invert some of the signals and see what happens
  • ercoerco Posts: 20,254
    edited 2015-07-23 00:38
    There is an FTDI utility called FT PROG available at http://www.gadgetgangster.com/news/45-designer-news/279-how-to-program-a-picaxe-with-any-ftdi-cable.html
    I tried it on a cheap Chinese FT232 adapter but it didn't work. Read the warnings if you decide to try it, for a while FTDI warned the utility would intentionally brick a counterfeit chip. Not sure if it bricked my chip or not, same (no) response before and after.
  • yousefyousef Posts: 21
    I was able to make it works by inverting all the signals. I had to modify some of the connections shown in the  basic stamp boards that are USB, but it finally worked at the end.
  • ercoerco Posts: 20,254
    Fantastic, so do you mean adding 3x hardware inverters to your Pololou 2102 module worked?
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