Shop OBEX P1 Docs P2 Docs Learn Events
stamp identification question — Parallax Forums

stamp identification question

mrbogeymanmrbogeyman Posts: 9
edited 2005-10-31 16:34 in BASIC Stamp
hello all.
i'm new to the bs2 and this is my first attempt at using a bs2 to control servo motors.
i've set up the stamp on a pcb with 2 capacitors as shown in the manual (page26).
when i click on run>identify, it there's a check in the echo column for com port 1 but the 'loopback' column is left unchecked. is the 'loopback' column suppose to be left unchecked? coz the picture in the manual shows both columns being checked.

also, i'm not any good at this basic programming stuff. anyone mind giving me an example of how a pulsout code for a servo motor should look like?
thanks.

Comments

  • allanlane5allanlane5 Posts: 3,815
    edited 2005-10-27 12:46
    The "loopback" checks a wire from pin 6 to pin 7 on the BOE board. If you leave this wire off, the "loopback" test will fail. This is supposed to be just a quick check to insure the cable is plugged in.

    Just put that wire in, and you should be OK.

    Oh, and that's pin 6 and pin 7 of the DB9 connector, on the BOE.
  • Chris SavageChris Savage Parallax Engineering Posts: 14,406
    edited 2005-10-27 14:00
    Hello,

    ·· Please give details of your system, such as Serial or USB, laptop/desktop, which board you're using and how you're powering it.· You shouldn't need to put any wires in if you're using a package you got from us.· Thanks.

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    Chris Savage
    Parallax Tech Support
    csavage@parallax.com
  • mrbogeymanmrbogeyman Posts: 9
    edited 2005-10-27 15:15
    I'm using a homemade board with 2 capacitors installed as shown in the bs manuals. i already shorted pins 6 and 7 and there is still no check in the 'loopback' column. it's connected to my pc using a straight serial cable using a windowsxp P4 desktop. thanks
  • Bruce BatesBruce Bates Posts: 3,045
    edited 2005-10-27 15:41
    mrbogeyman -

    Are you sure the Stamp is oriented correctly in the DIP socket?

    There is a picture in the Stamp PBASIC Manual, so that you can check for the proper orientation.

    Regards,

    Bruce Bates
  • Chris SavageChris Savage Parallax Engineering Posts: 14,406
    edited 2005-10-27 15:43
    Being that it's a home-brew board and you have no loopback I would definately start re-checking connections.

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    Chris Savage
    Parallax Tech Support
    csavage@parallax.com
  • mrbogeymanmrbogeyman Posts: 9
    edited 2005-10-27 16:10
    i've checked it a gazillion times already and there's still no loopback. i'll reconstruct the circuit.
    i've tried pulsing i/o number 0 to make the servo motor turn a bit but nothing happens. could this be due to the absence of the loopback?
  • Chris SavageChris Savage Parallax Engineering Posts: 14,406
    edited 2005-10-27 19:15
    Are you able to program the unit?

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    Chris Savage
    Parallax Tech Support
    csavage@parallax.com
  • mrbogeymanmrbogeyman Posts: 9
    edited 2005-10-28 16:55
    i took the whole circuit apart, and put it all back together again using the same pcb. and i discovered something new today. the power supply for my servo and the power supply for the stamp has to be on a common ground. so i did that, got it to be on a common ground. still no loopback, but this time i could program the unit...or at least i was able to make a simple pulsout command turn the servo motor a bit. funny thing is, my pc froze and restarted by itself. i've been warned that a short in the wrong place can cause the serial port on my pc to go fried too. please advice.
  • Chris SavageChris Savage Parallax Engineering Posts: 14,406
    edited 2005-10-28 17:40
    Not sure exactly what you're asking, but I suppose if you send the Vin (Short it) to the DTR line on the computer, then yes, you could damage your serial port.· But why would you try to make those kinds of connections?· It shouldn't be an issue.

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    Chris Savage
    Parallax Tech Support
    csavage@parallax.com
  • mrbogeymanmrbogeyman Posts: 9
    edited 2005-10-30 13:14
    my problem is i'm not getting a positive loopback.
    i've reconstructed the whole circuit using new components and still no loopback.
    now i got a new question. do i have to connect pin number 5 (ground) on the DB9 to the common ground? when i say common ground i mean the ground which my power supply to my motors and the battery that's powering the stamp are connected to.
    sorry for being so bothersome guys, i only have very basic knowledge on electronics.
  • Bruce BatesBruce Bates Posts: 3,045
    edited 2005-10-30 13:30
    mrbogeyman -

    ALL the low voltage grounds from all sources,·on the Stamp should be connected together at some common point. This includes all batteries and other sources of power, R/C servos, separate boards, off-board connectors, sensors, motors, LEDs, relays, etc.

    This is a perfect example of a problem which could have been solved with one message and one reply, IF a schematic or simple wiring diagram had been supplied. This is why such information is SO important to the troubleshooting process.

    Regards,

    Bruce Bates
  • mrbogeymanmrbogeyman Posts: 9
    edited 2005-10-30 13:40
    thanks for that bit of information.
    i got a common ground for all the low voltage points. ..everything that has a voltage supply has been connected to a common ground.
    what i want to know is whether the ground pin on the DB9 has to be connected to the common ground or not. confused.gif
  • Bruce BatesBruce Bates Posts: 3,045
    edited 2005-10-30 13:47
    mrbogeyman -

    I'm not sure why my answer wasn't acceptable to you. Try this instead:

    ALL GROUND CONNECTIONS, AND ALL GROUND WIRES, IN YOUR ENTIRE SYSTEM NEED TO BE CONNECTED TOGETHER AT ONE COMMON POINT, PERIOD, AND WITHOUT EXCEPTION.

    Does that make more sense?

    Regards,

    Bruce Bates
  • ForrestForrest Posts: 1,341
    edited 2005-10-30 13:55
    According to the schematics for all of Parallax's Stamp Development boards which you'll find here www.parallax.com/html_pages/products/boards/programming_boards.asp
    the RS-232 ground from the computer (pin 5) should be connected to the ground pin (Vss) of your stamps.
  • NewzedNewzed Posts: 2,503
    edited 2005-10-30 13:59
    I might add that pins 6 and 7 of the DB9··connected to the Stamp must be tied together.· This is not on the serial cable but on the Stamp DB9.· This is already done on the Parallax boards but if you are building your own it needs to be done.

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    Sid Weaver
    Do you have a Stamp Tester yet?
    http://hometown.aol.com/newzed/index.html

    ·
  • mrbogeymanmrbogeyman Posts: 9
    edited 2005-10-30 14:29
    alright. got all of that done already then.
    i had doubts because my project supervisor told me to not do anything with the ground pin on the db9 because it was dangerous. why so, he didn't mention. pins 6 & 7 on the DB9 have already been connected together. pin 5 on the db9 has already been connected to pin number 4 (vss) on my stamp.
    still i'm not getting a loop back. will seek help from the person who sold me this stamp tomorrow.
    thanks for the help guys.
  • Bruce BatesBruce Bates Posts: 3,045
    edited 2005-10-30 15:59
    mrbogeyman -

    If we assume everything that you've said to be true, and you're still not getting a loopback indication, and you are using a standard, straight-through serial cable from your PC, I'll go out on a limb here, and posit that there is only one practical answer left. The DB-9 connector on the PCB (Stamp carrier board) HAS TO BE MISWIRED. Below please find a rough drawing of both the PC DB-9 serial port connector, and the PCB DB-9 connector. If you were viewing a FEMALE connector when you wired it, it would be easy enough to cause this kind of a problem, or if you thought you were looking at the WIRED side rather than the·CONNECTOR side. You need to be viewing a MALE connector to wire·the PCB or carrier board DB-9·correctly.

    /code

    End views of both connectors viewed from the
    SOCKET side, NOT the WIRED SIDE!

    PC SERIAL PORT··· PCB or Stamp
    DB-9 Connector···· Carrier Board
    ························· DB-9 Connector
    __________········· __________
    \ 5 4 3 2 1 /········ ·\ 1 2 3 4 5 /
    ·\ 9 8 7 6 /············ \ 6 7 8 9 /
    ·
    ················
    ·· FEMALE················· MALE
    Pins Recessed········ Pins Exposed

    Connecting serial cable is DB-9 MALE to DB-9 FEMALE
    with ALL pins propagated straight through in the cable,
    and NONE cross-wired.

    code/

    Regards,

    Bruce Bates

    Post Edited (Bruce Bates) : 10/30/2005 4:09:25 PM GMT
  • SPENCESPENCE Posts: 204
    edited 2005-10-30 16:07
    Bruce,

    i have not been following this thread closely but!!!!!! Some manufaturers do not wire all pins.
    He should do a continuity check on his db-9 cable also.

    Spence
    k4kep
  • Chris SavageChris Savage Parallax Engineering Posts: 14,406
    edited 2005-10-30 18:58
    mrbogeyman said...(trimmed)
    i had doubts because my project supervisor told me to not do anything with the ground pin on the db9 because it was dangerous. why so, he didn't mention. pins 6 & 7 on the DB9 have already been connected together. pin 5 on the db9
    Consider yourself more well-informed than he is then.· Most devices don't talk well with each other without a common ground.· If you have signal wires in a system going back and forth without a common ground, then how is one system to know what level the signal is without a reference to ground?· Most systems require this.· Exceptions would be like RS-485 and other similar network systems.

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    Chris Savage
    Parallax Tech Support
    csavage@parallax.com
  • mrbogeymanmrbogeyman Posts: 9
    edited 2005-10-30 19:25
    bruce: i followed the tiny little numberings on the socket side of the male connector. from what i understand (based on what u said), the corresponding pin for hole number 1 comes out right at the back of it. if that's what you meant, then that's how i've connected it. i know i'm getting a little annoying. thanks for putting up with me.

    chris: I'm a mechanical engineering student...which explains why i don't know Smile about this, and only a dimploma holder in mechatronics. i hardly remember anything that's electronic because frankly, i don't like electronics. i'm just forced to make this stamp work because i've made a biped robot and now i have to make the electronic controls work. my project supervisor only has experience with the motorola hc11...so i'm pretty much left to die right now.

    i just realised a not too long ago the logic of having a common ground for components to 'communicate' and how stupid it was to ask whether or not to connect pin 5 on the db9 to the common ground...because obviously pin5 is connected vss...which is ground...so why connect it to the common ground then right? this is my first time putting my hand at electonics engineering...be it low level. the only other experience i had was playing with simple ics and building lil op amps in the college lab.

    thanks

    spence: what's this continuity check you're talking about? could be the answer to my problem.

    Post Edited (mrbogeyman) : 10/30/2005 7:34:40 PM GMT
  • SPENCESPENCE Posts: 204
    edited 2005-10-31 00:23
    Continuity is a complete circuit. Put ohm meter on pin 1 and measure resitance to socket 1. 2 to 2 3 to 3 etc. On each number to the coresponding number on the other end...

    Continuity check is how you test cables and connections with a ohm meter to assure that what is supposed to be connected realy is......

    Some manufacturers leave out wires to safe a few cents here and there, and they wronly guess that wire won't be needed. Fine. If you nead 5, 2, 3 all well and good but if they leave out 4 and 6 and you nead them. You are down the river without a paddle.

    73
    spence
    k4kep
  • mrbogeymanmrbogeyman Posts: 9
    edited 2005-10-31 07:58
    spence: thanks for bringing that up. i did a contuinity check even before your last post came in...i didn't know it was called a continuity check but i figured maybe not all the pins in my cable are connected since it was homemade by the person who sold it to me. so i tested for resistance between corresponding pins using a multitester and found that only pins 2,3,4 and 5 were connected. so i opened it up and wired it myself and NOW I GOT A POSITIVE LOOPBACK. i haven't tried pulsing motors yet, but i will get down to it soon.
    THANKS GUYS FOR YOUR HELP. APPRECIATE IT.
  • allanlane5allanlane5 Posts: 3,815
    edited 2005-10-31 16:34
    Yay. So glad you found the issue. Well done.
Sign In or Register to comment.