pbasic interpreter problem "No BASIC stamps found"

Amish Engineer

Hello All,

I purchased a pbasic interpreter chip for the BS2 in the 28-DIP·package in an effort to make my own BASIC stamp 2. So far, I have tried two designs: the OEM stamp schematic that I found on the website, and another schematic online that uses a MAX232 serial driver/receiver rather than all the transistors and resistors found on the OEM schematic.

OEM Schematic:
http://www.parallax.com/Portals/0/Downloads/docs/prod/schem/BS2Oem.pdf

MAX232 Schematic:
http://www.weethet.nl/images/basicstamp/homebrew.gif

So far, using both designs, when I hook up the stamp to the computer, the loop and echo return "yes", but when I go to program the stamp, a "No BASIC stamps found" box pops up. I've tried turning off FIFO buffers to no avail. I've checked that I'm getting +5v to all the chips. I am not using the brown-out detector, but I don't see why this would be an issue. The only difference between the schematics I can find besides the serial interface is that the OEM schematic does not have a pull-up resistor on the clock pin of the EEPROM, the OEM uses a resonator, not a crystal,·the MAX232 schematic has an optional reset switch, a diode on the receiver pin of the DB9 connector,·and the numbering of the I/O pins is different. So far, I've tried removing the pull up resistor on the MAX232 board; this did nothing. I've checked my wiring several times. The only things·I can think of that might be the issue are a.) I need to use an earlier version of the stamp software. b.) my pbasic interpreter is bad. c.) I need to use a ceramic resonator like the real stamps use, rather than a crystal. d.) my eeprom is bad.

I would like to get this thing working, any help would be appreciated. Thanks!
··

vaclav_sal

Make sure you have "straight" serial cable, no null modem.
Check for pin 2 to pin 2 and pin 3 to pin 3 continuity.
Than to lessen your frustration check the other tread ... TROUBLED.
Cheesr Vaclav
·

Amish Engineer

Thanks for the reply. Yes, I have a standard straight through serial extension cable. I'll keep looking through the forums. Thanks

modkil

looking at the schematic, a few things i would check would be the transistors(its kinda easy to mix them up, at least for me) along with the pins(shorts if not using a breadboard), the resistors(connections/wiring, and such), and just on the side would be the resonator since both breadboards and prototyping boards may have capacitance and noise issues.

the echo and loop return is only checking if pins 6 and 7 are connected on the db-9 connector.