Shop OBEX P1 Docs P2 Docs Learn Events
Basic stamp on breadboard — Parallax Forums

Basic stamp on breadboard

superchumpsuperchump Posts: 10
edited 2005-07-05 00:29 in BASIC Stamp
Hey guys,

Long time reader first time asker [noparse]:)[/noparse]

I'm transplanting my BS2 from my BOE to a typical breadboard. I have a 9 pin male connector that has pin 6 and 7 soldered together (DSR/RTS) and the rest are the necessary pins are connected to the programming pins on the stamp as they should be. I'm using the cable that came with my BOE though I don't think that makes a difference. I have no active filtering on that connection just yet. I'm powering the stamp with a Radio Shack 3-12 volt switchable power supply set to 9V that is connected to VIN and has a 3300uF cap bridging to ground as well.

The problem is I'm pretty sure the stamp is getting power (I'd check with my mulitmeter but I blew a fuse on it...oops). But firing up Parallax's programming software and trying to send it a program fails. So how do I connect the stamp to my breadboard easily? Am I missing something obvious?

Comments

  • superchumpsuperchump Posts: 10
    edited 2005-07-04 03:40
    Hmm...well out of sheer desperation I soldered a female 9 pin in the same way and throw a gender changer on it. Now I can upload a program just fine on the breadboard.
  • superchumpsuperchump Posts: 10
    edited 2005-07-04 08:40
    Well sure I can upload programs to it but now any program I have that uses serin and serout no longer work!

    The point of this all was to be able to have a generic setup that allows me to use the stamp on any breadboard or circuit board and allows me to both program the stamp through the Parallax softare and communicate with the stamp most likely through a tcl\tk interface.

    But I'm only halfway there it seems........
  • Philip GamblinPhilip Gamblin Posts: 202
    edited 2005-07-04 09:20
    You are aware that SERIN and SEROUT are usable on ALL I/O pins 0-15, right? The programming/DEBUG port is also usable by your program to talk to other hardware.
  • allanlane5allanlane5 Posts: 3,815
    edited 2005-07-04 12:33
    From what you describe, it sounds like you didn't have the pin numbering on the DB-9 correct. A DB-9 Female and a DB-9 Male do have the pin numbering 'mirror-imaged', so when you plug a male to a female the pins match.

    However, once a serial connection to the PC works for programming, it should work for SERIN/SEROUT. So the next thing that is probably wrong is that you are trying to use Hyperterm to talk to the BS2, and Hyperterm uses DTR, which will hold your BS2 in reset.

    The solution to this is to add the two .1 uF caps to the DTR line (also known as the ATN line, also known as pin 4 of the DB-9, also known as pin 5 of the BS2) as shown in the schematics of the BOE board. These two capacitors (one in series, one in parallel) de-couple the ATN line, so even if Hyperterm holds it high, the BS2 can still run.
  • superchumpsuperchump Posts: 10
    edited 2005-07-04 17:53
    Philip Gamblin said...
    You are aware that SERIN and SEROUT are usable on ALL I/O pins 0-15, right? The programming/DEBUG port is also usable by your program to talk to other hardware.

    Oh I know but I'd sure love to keep those pins open if needed. If the stamp has dedicated comm pins, why NOT figure out a way to use those? Yeah I know DEBUG works just fine. But if I build a graphical interface using tcl\tk I need to talk directly to an open socket on the comm port.
  • superchumpsuperchump Posts: 10
    edited 2005-07-04 17:56
    allanlane5 said...
    From what you describe, it sounds like you didn't have the pin numbering on the DB-9 correct. A DB-9 Female and a DB-9 Male do have the pin numbering 'mirror-imaged', so when you plug a male to a female the pins match.

    However, once a serial connection to the PC works for programming, it should work for SERIN/SEROUT. So the next thing that is probably wrong is that you are trying to use Hyperterm to talk to the BS2, and Hyperterm uses DTR, which will hold your BS2 in reset.

    The solution to this is to add the two .1 uF caps to the DTR line (also known as the ATN line, also known as pin 4 of the DB-9, also known as pin 5 of the BS2) as shown in the schematics of the BOE board. These two capacitors (one in series, one in parallel) de-couple the ATN line, so even if Hyperterm holds it high, the BS2 can still run.

    Bingo. I'm assuming those two small caps on the BOE next to the DB-9 connector do exactly that and that part is missing out of my circuit. Thanks a lot and I'll try this out soon when I get a chance!
  • superchumpsuperchump Posts: 10
    edited 2005-07-04 19:47
    Well I connected the caps to the DTR line; one in serial and one in parallel (I found a diagram to make sure it was correct just to be on the safe side). I can still program the stamp and also use the DEBUG window but hyperterm fails to display the serial output like is does on the BOE (using the same program). This is getting frustrating!
  • superchumpsuperchump Posts: 10
    edited 2005-07-04 20:11
    Hmm...I've noticed that the circuit layout of the BOE has no trace going to the VSS #4 pin though it has the caps coming off the DTR line and going straight to the ATN pin. Why is this done compared to the way I'm doing things (and how I've read things should be done)?
  • Chris SavageChris Savage Parallax Engineering Posts: 14,406
    edited 2005-07-04 20:14
    Hello,

    ·· Not sure which BOE revision you have, but on the Serial Rev C board pin 4 of the socket is connected to the ground plane on the bottom side of the board, which is where it should be connected to (Vss).



    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    Chris Savage
    Parallax Tech Support
    csavage@parallax.com
  • superchumpsuperchump Posts: 10
    edited 2005-07-04 20:55
    Yeah I have Rev. C

    But I thought that VSS Pin 4 was reserved for Pin 5 ground on the serial port.
  • allanlane5allanlane5 Posts: 3,815
    edited 2005-07-05 00:29
    Actually, Pin 5 on the DB-9 IS 'Ground', which also IS 'Vss', which also is the place the 'ground' side of the capacitor needs to be connected. The two (or three) grounds all need to be connected together.

    On the schematic, Pin 4 of the BS2 socket is indicated as going to Vss.· It's a convention of schematics that when a signal goes to 'ground' (or Vss in this case) then ALL the 'Vss' indicated wires are actually connected to each other.

    This allows creation of a "ground plane", which all grounds are connected to.· This simplifies the schematic a lot, but you do have to understand this convention.

    Post Edited (allanlane5) : 7/5/2005 12:34:12 AM GMT
Sign In or Register to comment.