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Basic Stamp2 OEM — Parallax Forums

Basic Stamp2 OEM

Hi, Can anyone advise me where I can purchase the EEPROM 24LS16B chip for the Basic Stamp2 OEM
It's been in my odds and ends draw for some time and now when connecting to my computer via the RS232 Serial Port the Edit software comes up with the message "Basic Stamp2 not found", This did happen in the early days and a new eeprom corrected the problem.



  • The 24LS16B is a standard device and should be available from most parts distributors.
  • You must have some other issues. The stamp will still be recognized even with the eprom pulled out of the system. So you can pull out the eprom test it again if it works then the eprom is bad. You can buy these at digikey, Mouser etc. And its P/N 24LC16B/P not LS. Cost about $0.35 each.
  • That said, it’s not likely that the 24LC16B is the reason for that error message. For example, you need to supply power to the OEM module because the module has to talk to the PC
  • Many thanks folks, yes LS was a slip of the keyboard. I get the same result with, or without power to the board. My knowledge of how the BS2 works is very limited, so thanks again for your helpful

  • TerryR,

    Did you assemble this module from a kit or buy it assembled from Parallax?

    Parallax sold assembled BS2-OEM modules back in the early 2000s.
  • Hi Genetix

    Yes I did buy my BS2-OEM from Parallax in the early 2000nds. It was already assembled and alas it had the same problem.
    I managed to locate John Smith in Leeds who was able to repair it for me. He said replacing the EEprom put things right. I bought the BS2 with the idea of developing a program to rotate a solar panel to follow the sun. I ran into mechanical problems and wasn't able to complete the program, so I thought I would have another go. My checks on my BS2 look to be normal. The Editor software shows which port it's connected to and when DC is connected Loop back and Echo have a Yes and it seems to make no difference if the EEprom is removed.

  • I'm guessing that it works now. And it shows the basic stamp on the loopback
  • I agree.
    But my alter-ego says he's never been to Leeds. Must be another individual with the same name then.

    (Think of the name chosen by the Doctor during his stay on Earth.)
  • Hi Bob and Buck

    No, I'm afraid my Basic Stamp2 OEM is not working, the BS2 Editor still comes back with "No Basic Stamp found"
    I have ordered a couple of eeproms from CPC, but they are temporary out of stock. At the moment
    I'm hoping the problem will be something minor. I'm using 4x 1.2V rechargable AA batteries and the circuit voltage is 5.3Volts. I'll just have to wait for the eeproms to arrive.
    "John Smith from Leeds" Sorry not enough information there. I should have said John Smith (Technical Support) of Milford Instruments Ltd, Leeds. I have emailed him with no success. I've recieved feedback: "Address not known".

  • I had the same problem with an old OEM board. So I took the BS2 dip40, the eprom, xtal, transistors etc. and wired it on a breadboard and it worked. You don't need the eprom to test it.
    It could be the brown out detector. You can remove it for testing just make sure your battery voltage is sufficient. The ground plane and the pin connections on the old OEM board is tight so make sure there is no shorting or sloppy soldering.
  • TerryR,

    First, check that the Interpreter and EEPROM are fully inserted into their sockets and that none of the pins are bent.
    Also, look at each of the solder connections for anything that may be suspect.

    I assume your battery pack is attached to Vin so what voltage are getting from Vdd?
  • Hi Bob and Genetix

    I am 82 this year, and unfortunatelly my soldering skills have deminished (eyesight and shakey hands), but now you folks have poked me in the right direction I can at least check out the Xtal oscillator etc with the scope. The microprocessor fitted to this BS2-OEM has 28 pins PIC16C57C.
    Problem, I can't find any for sale; not even on Ebay. Except for the Eprom all other chips (Interpreter etc) are included in the Pic chip.
    I am feeding +5.0 Vdc to the Vdd and 0.0 volts to Vss pins on the BS2 board, as I believe I would need 9-12Vdc to enable the 5volt Regulator via Vin and Vss
    Strange thing here, I can't remember livening up the BS2 board when I was programming? I just connected the computer, which has the old XP software, RS232 Serial port to the BS2 Serial port via a cable. I have now purchased a RS232 Serial to Usb converter to connect it to my Windows 10 PC, but the Basic Stamp is not found useing that either. I shall keep looking and bring you up to date when it happens.

  • I liked that BS2 OEM board they don't sell it anymore so now I make my own version of it to suite my needs. Here's the original schematic
  • Hi Bob
    Many thanks for the BS2 PDF circuit.

    I have good and bad news? While probing about with the scope the little rascal came to life, so I continued clicking on new Editor programs until it finally went back to the No Basic Stamp found. So it looks like a bad connection somewhere.
    I'll remove the plug in Eprom and PCU and have a go at resoldering all the joints.

    Best regards Terry.
  • TerryR,

    Which RS232 to USB converter are you using?
    Programming the BS2 requires very strict timing so it will fail with some cheap converters.
  • Hi Genetix

    A very good question and thanks for asking; fortunatelly, not knowing the problems attached to the converters, I bought mine from Parallax Part number #28030.

    Best regards Terry
  • TerryR,

    So you have the Parallax USB-to-Serial Adapter which is guaranteed to work with the BS2.
  • Hi Genetix

    Yes your right, I have bought a Parallax USB-to-Serial Adapter for the BS2. I realise my BS2 has an intermittent fault. I'm hoping to solve the problem by resoldering the track side joints.

  • Hi all

    I'm still trying to get my BS2-OEM working. I have resoldered all joints I considered dodgy, but alas I'm getting "No Basic Stamp found"
    I have the BS2 connected via RS232 Serial Port to my old Windows XP, which has downloaded Basic Stamp Editor.
    The BS2 is connected to 5.2Volt on it's Vdd+ and Vss Ground pins. I'm using a 10X probe and my scope is set for 1.0V per div.
    EEprom pins 5-Data and 6-Clock show wave forms, but on the Xtal pins 26 and 27 on the BS2 chip no wave forms show.
    Clicking on "identify" in the Editor screen The display shows (Port com-1) (Device Type (empty)) (version (empty)) (Loopback (yes)) (Echo (yes)) Clicking on "Run" results with "No Basic Stamp found" No wave forms on the Xtal looks a pretty obvous problem, but I'm not sure what could be the cause?

  • davejamesdavejames Posts: 4,031
    edited 2019-04-21 22:23
    TerryR wrote: »
    I'm still trying to get my BS2-OEM working.
    EEprom pins 5-Data and 6-Clock show wave forms, but on the Xtal pins 26 and 27 on the BS2 chip no wave forms show.
    No wave forms on the Xtal looks a pretty obvous problem, but I'm not sure what could be the cause?
    Hi Terry - is there any chance you can provide up-close and clear pictures of the board? We might be able to spot something.
  • Hi davejames
    Yes I could take some close up photos, but I'm not sure how to post them here? Ok I'll take some photos and see if I can upload them.

  • Hi davejames
    My photography skills are not too good. I took these with my android phone. I hope they are not too big, as I didn't realise they are over a Meg pixel.

    The last program I Tokenized operates the hardware fine, but alas it won't Tokenize any further programs, as yet.

    5376 x 3024 - 3M
    5376 x 3024 - 4M
    5376 x 3024 - 4M
    5376 x 3024 - 4M
  • yisiguroyisiguro Posts: 52
    edited 2019-03-31 06:26
    How about monitoring RES and VDD lines: Isn't it Brownout conditon (i.e. less than 4.3V) met?

    (edit: I'm trying to summarize)
    -This board was purchased from Parallax and all components are fully assembled and soldered from the beginning.
    -Powered by batteries connected to directly VDD (not via VIN) at 5.3V.
    -I2C signals SCL and SDA of 24LC16B are alive.
    -But PIC's oscillator signal is silent.

    As if MCU is in SLEEP...
  • Check the components make sure the correct transistor is in the right place etc. A sure way to test it would be to build it on a breadboard
  • Hi DigialBob and Yisiguro

    Thank you for your interest. Yisiguro, here is some history of my BS2 OEM's. I purchased it from Parallax in 2009 completely assembled. After some months, still in it's package, I decided to experiment with a short program "traffic lights sequence" Unfortunately I found when clicking on RUN, in the Editor, my monitor would display "No Basic Stamp found" I had it repaired by a recommended Parallax contractor. On close examination I could not see any new soldered joints, but was told they just replaced the EEprom. After it's return I have written and run quite large programs with no problems at all. But it has been in it's box since 2011. Two weeks ago I found it's not working again with the same fault. I had saved some of my programs to the Editor. While testing during the last couple of weeks the Editor began to work, so I selected my "Traffic lights" program and clicked "RUN" I was pleased to see the Debug window, proving the traffic lights program had down loaded. The BS2 OEM will now drive the Traffic lights hard ware, but I can no longer download any other software.

    I get your point Bob; I could purchace another 20Meg xtal and a couple of transistors etc. I'll give it a go on a bread board and see what happens.

  • you could put the BS2 IC in an eprom programmer if you have one and just hit the read. It should show about 4-5 lines of hex just to make sure its not burnt up.
  • DigialBob

    Good thought, but I haven't got such a thing. I'm pretty sure the BS2 hasn't burnt up. Do you know of a way I could test the XTAL if I removed it? I have a signal generator and a 200Mhz Scope.

  • kwinnkwinn Posts: 8,693
    edited 2019-04-01 14:19
    You could assemble a simple oscillator circuit to test the crystal using a transistor, hex inverter chip, or an opamp. Google "crystal oscillator" for circuit suggestions.
  • yisiguroyisiguro Posts: 52
    edited 2019-04-07 02:37
    TerryR wrote: »
    The BS2 OEM will now drive the Traffic lights hard ware, but I can no longer download any other software.

    That is, you say, your BS2 still acts Traffic Light Sequencer EVERY TIME after resetting the board, for example, powering on, failing download another code, right ?

    According to Tokenizer Manual "BASIC Stamp Programming Protocol", BASIC Stamps have severe communication timing.
    If RES is asserted too long and relatively break condition of Tx is shorter, BS2 chip does not respond to host PC, and then run already stored code Traffic Light Sequencer, I suspect.

    I tried some simulation with LTSpice:
    Predicted duration of RES pulse is about 4msec long at 10V(peak to peak) of DTR line.

    I tried measuring pulse width of DTR and TXD, but its result is not what I expected.
    Actually, pulse width of DTR is only 10m, and of TXD is 70m second long.
    This result shows that RES pulse width is not longer than 10m second and there is enough time to last break condition of Tx.
    So, RES signal is not guilty.
    1366 x 736 - 41K
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