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OEM Pbasic2SX Interpreter connection — Parallax Forums

OEM Pbasic2SX Interpreter connection

kroki78kroki78 Posts: 13
edited 2007-01-12 03:05 in BASIC Stamp
Hi there!
I used Basic Stamp's for long time, and now i want to biuld a bit complexer project with an BS2SX integrated on it.
I bought a few BS2SX interpreter chips(an SX28 programmed with the BS2SX embedded basic interpreter)·and would like to build the whole project over/arount it.
First i needed the circuit for the serial programming and debugging.
I tried to build the exact circuit seen on the OEM BS2SX board schematic. didn't work. Then i tried to build the circuit on the BS2SX IC. didn't work either.
In both cases i used the same parts as written on the schematics.

Could anyone tell me a way to connest the interpreter chip to the PC serial port so i can program and debug it.
(I really don't want a BS2SX IC on the board, and don't need a daughter-card like the OEM version.

Please help me guys!

Best regards:

Kroki

p.s.: maybe MAX232? but how?

Comments

  • Chris SavageChris Savage Parallax Engineering Posts: 14,406
    edited 2007-01-11 15:11
    First of all are you sure you have a pre-programmed interpreter chip (DIP)? A blank SX28 won’t work. Also, the minimum requirements for the chip to function are the EEPROM and Resonator listed in the schematic, as well as the support components, which are a few resistors and capacitors. To program it you can either duplicate the circuitry in the OEM schematic, or is you have a USB2SER, PropPlug or PropClip you could use the schematic located at the following link. Take care.

    http://forums.parallax.com/showthread.php?p=567989

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    Chris Savage
    Parallax Tech Support
  • kroki78kroki78 Posts: 13
    edited 2007-01-11 15:38
    Thanx for the advice, but what I did: I biult the exact circuitry from the original OEM schematic.

    No serial comm. this way.

    If it's possible, i need to avoid external clips and other stuff, so i can easily connect it to any serial COM port of any PC.

    I bought the preprogrammed chip from the local Parallax retailer, and after a few missed trials, i checked it with an SX programmer and it is Code Protected, so it should be OK.
  • Chris SavageChris Savage Parallax Engineering Posts: 14,406
    edited 2007-01-11 15:41
    If you had an actual OEM BS2sx Module you could swap the chip out to be sure nothing has happened to it since. I’m still not clear on what you have done. If you duplicated the circuitry and have no serial communication then the first questions should be do you get echo and/or loop back?

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    Chris Savage
    Parallax Tech Support
  • kroki78kroki78 Posts: 13
    edited 2007-01-11 15:52
    Loopback works fine, i will check echo.

    Sadly i don't have an assembled OEM PCB, so i can't try the SX.



    maybe i will try to make the distributor try this one out for proper working.



    If i try to communicate with the assembled SX stamp, what should i get, or how can i check the proper communication in terminal?
  • Chris SavageChris Savage Parallax Engineering Posts: 14,406
    edited 2007-01-11 17:01
    Do you have the correct EEPROM and Resonator connected? Do you have a scope to check your resonator signal?

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    Chris Savage
    Parallax Tech Support
  • kroki78kroki78 Posts: 13
    edited 2007-01-11 19:58
    I have 24LC128 and 50Mhz resonator on the board. the resonator works fine in an SX28 based project.

    I tried the EEprom with that SX28 project and it's OK, now it's filled with FF. could it be that it chould be filled with 00's to get started?
  • Chris SavageChris Savage Parallax Engineering Posts: 14,406
    edited 2007-01-11 21:22
    No, the EEPROM contents don’t matter when it comes to programming it. Did you find out if you have echo or loop back when you try to identify it?

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    Chris Savage
    Parallax Tech Support
  • kroki78kroki78 Posts: 13
    edited 2007-01-11 21:33
    in between i made a little measuring. i figured out, that the lvl of the signal going to the SX from the serial port is under the TTL signal level, and I started to·search·for a ·"why".

    btw. there was no echo. nothing at all.

    it seems that the SX28 is working correctly with the oscillator and the EEPROM is OK too, as sayd before.

    I think there will be something with one of the transistors. maybe i got a damaged one from the shop. Or it's·slower·than I need. i'm beginning to think about a circuit with MAX232. it should work, only the ATN signal from the serial port needs a transistor circuit to the MCLR pin on the SX.
    Any idea?

    If I can manage to make a serial to TTL for the OEM, then I will post it here,·maybe someone can use it.
  • Chris SavageChris Savage Parallax Engineering Posts: 14,406
    edited 2007-01-11 22:03
    You should have echo just by making the connection to the module. You should have echo if the circuit is powered, even if the interpreter isn’t responding. This indicates your interface hardware is where there current problem is. Echo is achieved in part by the 4.7K resistor across the TX/RX lines…So something is missing in your circuit.

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    Chris Savage
    Parallax Tech Support
  • RobotWorkshopRobotWorkshop Posts: 2,307
    edited 2007-01-12 01:47
    I ran into a problem when I was first using the BASIC Stamp OEM chips and
    found that the regular Stamp modules would work fine when the RX and TX
    lines were swapped. I had been using a MAX232 which even with the 4.7K
    feedback resistor would only work when wired the way it should be. It threw
    me off track for a bit since I never expected that the Stamp modules would
    work either way. Some of it was highlighted in the following thread:

    http://forums.parallax.com/forums/default.aspx?f=5&m=140260&g=142344#m142344

    I also have a BS2SX DIP on a protoboard which works well too with the
    MAX232.

    Now i'm trying out the Propeller but am running into a different issue since
    it looks like the reset line is the opposite as the stamp.

    Robert
  • ForrestForrest Posts: 1,341
    edited 2007-01-12 03:05
    I saw this comment posted on a well respected website that sells electronics to hobbyists:
    "Not all 2N3904 NPN transistors are wired the same. Always check the pinout of the device in hand against your footprint."
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