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BS2 without any boards? — Parallax Forums

BS2 without any boards?

tianshiztianshiz Posts: 6
edited 2009-04-02 18:37 in BASIC Stamp
Is it feasible to hook up a BS2 onto a clean breadboard and connect it to the PC with a FTDI usb breakout board? I tried simply lining up the Vin, Vss, Sout and Sin and ATN, but the ID process only showed an echo from the port. Loop back displayed "no" and device type was blank.

Am I wasting my time here? I do have a BOE, but I need to do without the big size of the board.

Any help is appreciated!

Comments

  • FranklinFranklin Posts: 4,747
    edited 2009-03-30 21:01
    Could you draw a sketch of how you have things connected? It should work as a standalone device.

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    - Stephen
  • tianshiztianshiz Posts: 6
    edited 2009-03-30 21:18
    bs2.th.png

    This is what I did essentially. However, my ftdi breakout board only supplies 3.3v to the Bs2 which does not meet the 5v requirement. So, I hooked up a 6 volt battery with the vin and vss.

    No luck with this...thanks for the help!
  • FearTurtlesFearTurtles Posts: 89
    edited 2009-03-31 02:48
    Are you sure the FTDI supplies 3.3v and that it does not run off 3.3v? I'm thinking that the 6v applied to the 3.3v pin on the FTDI killed it.
  • tianshiztianshiz Posts: 6
    edited 2009-03-31 12:25
    The 3.3v pin on the FTDI is meant to supply power from the usb to the board. But, I see what you mean that the 6v might of been applied to the 3.3v. However, I've also tried the setup where I didn't use the gnd or the 3.3v pins at all. I simply used the respective wires of a 6 volt battery pack.

    Regardless of that, does this setup look theoretically correct?
  • tianshiztianshiz Posts: 6
    edited 2009-03-31 20:31
    I looked up the bs2's schematics and tried the schematics on the bottom of this page:
    http://www.parallax.com/Portals/0/Downloads/docs/prod/schem/BS2revJSchematic.pdf
    still, i get only an echo. No loopback what so ever...I'm really stuck on this, but I know that using the stamp as a standalone is entirely possible. Are there any tutorials out there for this?
  • Mike GreenMike Green Posts: 23,101
    edited 2009-03-31 20:40
    I'm not sure, but I believe that the BS2 requires an inverted signal since the Sin and Sout signals are intended to connect directly to RS232 signal levels. You could use a USB to RS232 adapter for this. Parallax makes one that works nicely with a Stamp. You could de-solder the DB-9 connector from the unit and make a direct wired connection. I suggest adding the two capacitors shown in the DTR to ATN part of the diagram near the front of the Stamp Basic Manual.
  • JDJD Posts: 570
    edited 2009-04-01 06:02
    Tianshiz,

    The picture really isn't clear on the Sin and Sout pins connected to the module. However, the Loopback stating no is an indication of the cable or adapter being used. Have you installed the FTDI drivers for that module?

    Mike, you are correct; the BASIC Stamp uses inverted baud to communicate to the PC. From the picture above, it also looks like the voltage·(Vin) is connected to the voltage coming from the USB port. That voltage doesn't exceed 5 VDC; with that in mind, you could connect that voltage input directly to the Vdd pin of the BASIC Stamp since it only uses 3 mA for operation and will not exceed the 5 volt tolerance of the pin. The Vin pin is connected to the 5 volt LDO regulator; so you would want to apply more than 5 VDC to that·pin to get it running accurately. The Vss pins (4 and 23) on the BASIC Stamp are connected internally, so by connecting one you have a common ground. It is strongly suggested that you use the connections stated in the BASIC Stamp Syntax and Reference Manual (page 28) when connecting to a serial port as Mike Green offered. If you do not have this manual you can download it for free at the link below. I hope this helps, and even though this isn’t a supported connection to the BASIC Stamp, we will try to help however we can.

    BASIC Stamp Syntax & Reference Manual:
    http://www.parallax.com/Portals/0/Downloads/docs/prod/stamps/web-BSM-v2.2.pdf

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    Respectfully,


    Joshua Donelson
    www.parallax.com
  • tianshiztianshiz Posts: 6
    edited 2009-04-02 17:40
    Hi,

    I have tried to follow the schematic in the page here:
    www.parallax.com/Portals/0/Downloads/docs/prod/schem/BS2revJSchematic.pdf
    I connected the Sin and Sout with the respective pins tx and rx as well as provided an external battery pack for the 5v+ requirement. I even used capacitors as suggested, but I'm still getting the same result here.
    As for the FTDI driver, I have it installed and the breakout board worked with my arduino.
    Thanks for your help!

    Sorry for the poor illustration, but this is essentially what I did:
    take2.th.png

    Post Edited (tianshiz) : 4/2/2009 6:26:14 PM GMT
  • Mike GreenMike Green Posts: 23,101
    edited 2009-04-02 18:37
    You will not be able to use the FTDI module for the reasons I've given. The capacitors are necessary and clean up the DTR pulse, but the voltage levels on the receive and transmit lines on the FTDI module are wrong for the Sin and Sout lines of the Stamp. You could place a MAX3232 between the FTDI module and the Stamp and that would fix the levels. Parallax's USB to RS232 adapter essentially does this.
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