USB2SER interface to Basic Stamp II

rwheaton

Hey there,

This post has given me hope (http://forums.parallax.com/forums/default.aspx?f=21&m=106379) but alas I have not yet evolved to that level of sophistication.

My wimpy little home made PCB is using a BS2 REV G (http://www.parallax.com/detail.asp?product_id=BS2-IC). Besides the fact that it is pretty simple - everything is in one tidy little 24 pin DIP - it looks damn cool. When i point to the "robot brain" on my robots to co workers and other lesser life forms, they say "yeah, that looks like how i had always imagined a robot brain would look - if i had an imagination" (truth be told, most just grunt and drool).

Having said all that, i am super paranoid about frying the unit at $50 a pop, i don't really experiment much with the circuitry surrounding it. What i would love to have though is a fancy little 4 pin header that would connect seamlessly to my USB2SER module for inline programming and debugging using the Parallax GDE.

is there a simple yet clever schematic between SOUT, SIN, and ATN that would suit my needs?

thanks in advance for any feedback ...

russ

Jon Williams

If you want "simple", let me suggest you get a USB to Serial adapter and just put a DB-9 and a couple caps on your board (see attached schematic).· You see, the USB2SER is an inverter, and the BS2 module has inverters on it -- this means that if you want to use the USB2SER to program your BASIC Stamp module you have to put yet another inverter between the two.

Have a look at page 8 of the PDB schematci and you'll see how.· Here's a link to that schematic:

http://www.parallax.com/dl/docs/prod/boards/PDBSchem.pdf

Still... I think this product is going to be easier for you to deal with, and keep your programming interface simpler:

http://www.parallax.com/detail.asp?product_id=800-00030

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Jon Williams
Applications Engineer, Parallax

Chris Savage

Russ,

·· In fact there is such a schematic.· It's on our website on the product page for the Professional Development Board.· That schematic can show you how to add the transistors needed to handle a BASIC Stamp Module from the USB circuitry.· The thread you referred to was created for those who integrate the BASIC Stamp into their designs and didn't want to have to implement the extra circuitry required to program via serial or using a USB to Serial Adapter.

·· The true output of the USB2SER would normally be compatible with a direct connection to the interpreter chip but the design needed to account for echo and a driven output.· On a BASIC Stamp Module though the connection is expected to be inverted and the USB2SER is not so you would either need a driver or the transistors from the PDB schematic.· I hope this helps.


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Chris Savage
Parallax Tech Support
csavage@parallax.com

rwheaton

Thanks very much for the direction. i am digging through that part of the prof development board now as i get time. it looks to be exactly what i was looking for.

thx again.

russ