View Full Version : HELP!! BS2 won't program no more!!

04-26-2007, 05:03 AM
I'm using a BS2 OEM (pre-assembled) and trying to program it using parallax's Basic stamp windows software.

the Com port is correct!· But when it is trying to program, it just says it can not find the BS2!!???

I have tried inputting 5V and 9V into the Vin and ground to the Vss.· I know there is power on those pins because I have a volt meter.· Also, the RES reset pin also shows 5V high which means the board should be working.

Also, I have grounded or driven the RES pin low to attempt a reset but this also did not resolve the solution.

can anyone help?· or tell me why it won't program?· it can't find the BS2 when it is trying to program.

Mike Green
04-26-2007, 06:02 AM
It won't program because, even though you've hooked up everything right, you probably didn't really despite the best of intentions.

Seriously, the most common reasons for not being able to "find" a Stamp are 1) Something's hooked up improperly 2) The PC I/O drivers are either installed or configured improperly 3) There's no power to the Stamp.

Note that the PC expects to be able to force the Stamp to reset using the DTR serial control line. Look at the schematic in the front of the PBasic manual for a correct schematic for this part of the interface between a Stamp and PC.

Chris Savage
04-26-2007, 07:00 AM

Is this a laptop or desktop computer? Are you using a straight serial connection or a USB adapter? What type of cable? Do you get loopback and/or echo when trying to ID the Stamp Module?

Chris Savage
Parallax Tech Support

04-26-2007, 07:44 AM
Yes, this is a desktop.

I am getting LOOPback is YES, ECHO is NO.

I am using a USB->Serial cable but it DID work before numerous times!! Then this morning, all of a sudden, it no longer worked.

but it is NOT programming no more!! =[

I just got this board last week, and I really need to get it working because·I have a project due by May 18.· Can Parallax cross-ship me another one or perhaps replace it for me?

Also, I have tried using my 5V battery and 9.6V battery.· Both do not work and again, I do see power measured on the pins of the BS2.

I have also just tried it on my dad's desktop which has a real RS232 port.· I plugged the port right into his comp and load up the program.· It also does not program!! It says loopback yes, ECHO no and no BS2 found.


Post Edited (l337hxr) : 4/26/2007 1:05:57 AM GMT

Chris Savage
04-26-2007, 08:23 AM
Which brand adapter are you using? Some, such as Belkin do not work with the BASIC Stamp. If it is a unit that worked before you may have had to change the latency or disable the FIFO buffers. If for some reason the port number changed those settings may be lost and have to be set again. As for cross-shipment, you would need to contact us directly on that. We have a return policy and the unit you have will need to be tested to determine why it stopped working (defect or damage).

Chris Savage
Parallax Tech Support

04-26-2007, 08:34 AM
Hello Chris, i digged up a PDF that explains the combination of if loopback is yes or echo is yes or no.
I'm using an adapter i bought on ebay.· It's generic one.· But again, i have tested it on a built-in RS232 port on a 3rd desktop computer....no go.

I noticed that with no power connected to the BS2, I get Loopback YES, ECHO yes. With power connected, I get loopback YES and ECHO no.

Chris the com port is correct and I've tried 3 different computers already. One desktop and laptop used my USB->Serial adapter and the adpater works because I just hooked it up to a GPS device and it is sending data to the hyperterminal.

The last desktop has a built-in RS232 port on the motherboard and that does not work as well.. i get the same LOOPback yes, ECHO no error. There is only one COMport and it is set correctly.

I have also disabled the FIFO in the USB->Serial Com Port and it's still a no go.· Same error.


Post Edited (l337hxr) : 4/26/2007 1:41:46 AM GMT

Chris Savage
04-26-2007, 11:13 PM

I am still not clear whether you mean the OEM BASIC Stamp worked before or the USB adapter. Saying the adapter works because it works on a GPS Module doesn’t count. The Belkin adapters (and several others) also work on other devices but don’t program the BASIC Stamps. It also doesn’t make sense that you get ECHO with no power but don’t get it when power is on. Are you using a standard serial cable on the machine you did a direct serial connection or is it a cross-over cable? Is it a custom made cable? How long did the BS2 OEM Module work before you started having problems?

Chris Savage
Parallax Tech Support

04-27-2007, 01:27 AM
Well I received the OEM basic stamp 2 on saturday April 21.· It was working good on sunday, monday, and tuesday using my USB->Serial cable.· This worked on both my laptop and my desktop.

Something to note: immediately the first day I received my BS2, i noticed a distinct funny smell· like a smell of burnt electronics.· I didn't thought too much of it at first, because it worked the first day.· I don't know if this is an issue, could u check?· Anyways, it still has that smell but that smell has been there since the first saturday i got it.

Now, the device stopped working wednesday morning when i plugged it into my laptop.· Just the usual USB->Serial and I did select com port correctly.· It basically said loopback "YES", echo is "NO".· I have only two wires connected to the pins.· +9V into the Vin, and ground to VSS.· I have a volt meter that i tested and I see +4.95V on the Vdd pin and also 4.95V on the RES reset pin.· This tells me the BS2 stamp is running.

I have driven the RES pin low (ground) for about 2-3 seconds multiple times to attempt to reset it, but this does not work.

This is now the 4th computer I"ve tried and it still does not work...and I am at work here now using my work computer and using the USB->Serial.

My third computer I tested has a built-in RS232 port which is a male port.· I connected the BS2 oem module into the port directly onto the back of the computer (using no serial cables) and I still experience the same problem.··I can't program it beacuse it says Loopback yES, ECHO is no.

please help me... i really need to get this working soon so I can work on my project and turn it in on May 18.

Is it really that hard to accidentally zap a BS2 oem???· Could I have zapped it?··i dunno, I always carried it in it's own little electronic-magnetic static pouch during transport.

first computer - dell laptop using usb -> serial.· worked good for 4 days.
second computer - custom built desktopusing usb-> serial.· also worked good for first 4 days.
third computer - has BUILT-in RS-232 port. does not work.· plugged straight into the rs232 port..no cable..direct connection.
fourth computer - my other laptop using usb-> serial..no worky.· same error...no echo.

Post Edited (l337hxr) : 4/26/2007 6:41:04 PM GMT

04-27-2007, 01:34 AM
And here are some images for you.

with the BS2 connected and powered on.


with the BS2 connected to the computer but no power to the Vin and Vss pins.


finally, with the BS2 connected to the computer and power applied and attempting to program.



please, please help.· I would love for an exchange, I dont want a refund, i just want it to work.· I hope parallax can cross-ship it.· Should I call in for a RMA number?·

04-27-2007, 01:48 AM
Just to re-iterate...

i have the following device:

Stock#: 27290 Category: BASIC Stamps-OEM
BASIC Stamp 2 OEM Module (Assembled)
Price: $59.00

i am NOT using a BS2 IC chip standalone. I am using the exact device above...

Chris Savage
04-27-2007, 02:14 AM
An RMA has been issued for this module.

Chris Savage
Parallax Tech Support

04-27-2007, 02:46 AM
thank you Chris, you've been so helpful!!· the bs2 is on it's way back, I just dropped it off the mail.

04-27-2007, 07:00 AM
I'm concerned there's something wrong with your setup.

The "Loopback" checks that pin 6 is looped back to pin 7 -- it validates the plug is plugged in, works with power or not.

The "Echo" verifies that the recieve transistor is connected to the transmit transistor. For that to work when power is OFF but NOT when power is on implies a grounding problem, I think. That, or a burned out transistor maybe?

Vin expects 6 volts or higher, and drives the input of the linear regulator. If you put 6 volts or higher directly to Vdd, you bypass the linear regulator and will burn up the PIC processor -- the heart of the OEM BS2.

Were I you, when I get the system back, I'd check the voltage difference (with a volt-meter) between the DB-9 pin 5 ground and the Vss ground of the BS2.

Chris Savage
04-27-2007, 08:08 AM
Echo comes from a 4.7K resistor that is effectively connected between the RX and TX lines right where they enter the BS2. That said it is possible that a problem on the inside could hold one side in a particular state and prevent echo. We’ll find out soon enough. Take care.

Chris Savage
Parallax Tech Support