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JetLee
06-07-2005, 05:57 AM
Hi,

I have an application using basic stamp·BS2p40 that requires the use of the built in serial port· for serial communications with a PC.
When we restart the PC, the reset line of BASIC stamp go high and low many times, which causes the BASIC reset many times.· Do we have any way to disable the reset line when we restart the computer?

Thanks,

Lee

Beau Schwabe (Parallax)
06-07-2005, 06:06 AM
Lee,

You can disconnect the DTR line going to the Stamps ATN line, but by doing this you will not be able to program the Stamp unless you reconnect.

Will you be programming the Stamp from this computer?

A manual switch would be one solution, another solution would be a software switch.

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Beau Schwabe (mailto:bschwabe@parallax.com)

IC Layout Engineer
Parallax, Inc.

Newzed
06-07-2005, 06:07 AM
Can't you just disconnect the serial connection until your PC stabilizes?· The Stamp is getting reset by lows to the ATN pin and there is no practical way to disconnect it.

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Sid Weaver
Need a bezel for your LCD?

Newzed@aol.com (mailto:Newzed@aol.com)
·

Newzed
06-07-2005, 06:12 AM
Or better still, just remove the Stamp power until the PC stabilizes.

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Sid Weaver
Need a bezel for your LCD?

Newzed@aol.com (mailto:Newzed@aol.com)
·

JetLee
06-07-2005, 07:04 AM
Beau, since we deliver the system to the users, we cannot disconnect the DTR line or serial connection at all. We have thought about hard switch but the user might still forget how to switch it off before restart computer.

Sid, how could we know the PC stabilized? If we know it, we can open/close the ATN to disable/enable the stamp or add a relay to romove the stamp power.

Thanks so much for all supports.

Lee

Jon Williams
06-07-2005, 07:18 AM
Lee,

If the end-user is not going to be reprogramming the BASIC Stamp then disconnecting the ATN pin as Beau suggests is the way to solve the problem. The DTR pin is used (via ATN) to reset the BASIC Stamp for reprogramming -- but that's the only thing it's used for. Disconnecting it after the Stamp is programmed will not affect serial communication on the programming port.

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Jon Williams
Applications Engineer, Parallax

Newzed
06-07-2005, 07:20 AM
It appears Jon has the best solution - simply disconnect the ATN after you have programmed the Stamp.

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Sid Weaver
Need a bezel for your LCD?

Newzed@aol.com (mailto:Newzed@aol.com)
·

JetLee
06-07-2005, 07:42 AM
Jon,

If the software needs to be updated in the future, we are planning to send SW to the end user to do that.
Tks,

Lee

Forrest
06-07-2005, 07:49 AM
How about a momentary contact switch (normally open) across the ATN line. Push and hold the switch to reprogram the Stamp.

Beau Schwabe (Parallax)
06-07-2005, 12:23 PM
If you wanted to get tricky, you would not need to use a relay...· Just an external NPN transistor and a couple of resistors
would do the trick.· Control it through the Printer port, or better yet... I will need to search my notes, but there are actually
three pins on the COM port that you can directly control through software (on the PC side)

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Beau Schwabe (mailto:bschwabe@parallax.com)

IC Layout Engineer
Parallax, Inc.

PLJack
06-07-2005, 05:46 PM
I get the impression you are sending your customers the stamp mounted on the OEM dev board.
This board also has a reset button your customers probably should not be using.

Would it make more sense to build a small PC board that has a programming port AND an serial port for their computer.

Or better yet, to avoid confusion / tech calls, a serial port and a 4 pin header with a programming adapter.

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Jack