BASIC Stamp2p24: Does it come with integrated UARTs or does it tout serial comm

ice-egoz

Hi, My project requires 2 hardwares{GSM modem and GPS receiver} to be integrated to the BS2p24.
I know that I need to use the MAX chip {MAX238CNG}. I know that it is a level convertor. So does the BS2p24 has UART? Or do I even need UART? My part of the project is to come out with 2 serial ports using the MAX chip. So that the GSM modem and GPS receiver can be integrated to the BASIC Stamp. I know I need to do cabling but i want to check whether whatever I have·typed makes sense or not. I do need capacitors but do i have a certain criteria for choosing one? How about resistors? Do I need them?

DntGvaSht

you can communicate with serial devices on any 1 or all of the pins of a basic stamp.· For more information see http://www.parallax.com/html_pages/downloads/basicstamps/documentation_basic_stamp.asp

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ice-egoz

The thing is that I will need 2 serial devices to plug into the BASIC Stamp. So therefore Im using the MAX chip which will help. I want to know whether the BASIC Stamp Has UART or serial communication capability.

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I need all ya guidance Masters. [noparse]:)[/noparse]

AlWilliamsAWC

The Stamp can do serial I/O on any pin, but this is done in software. It isn't a UART in the strictest sense of the word. So the short answer is that you can connect -- in theory -- up to 16 or 17 serial inputs or outputs (if you count using the programming port which has some limitations). So you could (in theory, again) drive 16 serial printers or read from 16 GPS receivers or talk to 8 modems (8 inputs and 8 outputs). But here's the catch: you can't do them all at the same time.

Suppose you have 2 GPS receivers connected to the Stamp so that they send data out every second. The physical connection is not a problem. But the Stamp can only listen to one at a time. If the Stamp is listinening to GPS "A" when GPS "B" sends its data, that data is lost. If the Stamp is doing something else while either GPS sends data, you lose data. There is no buffer. In some cases, you can use hardware handshaking to mitigate this problem (but that costs I/O pins, of course). There are also some "UART/buffer" chips that will work (see http://www.wd5gnr.com/suart.htm).

So there isn't a simple answer. Yes, the Stamp can do many serial channels with the addition of a level converter (see http://www.awce.com/rs1.htm). But it takes planning in software since the serial channels are software-only and have no buffering. Even handshaking can have problems since most devices don't react instantly to handshaking.

We've often considered making an "RS232 coprocessor" for the Stamp, but I've never been completely sure what feature set it would have. The MAX3110 chips come close and have level conversion onboard but they are expensive and somewhat hard to get.

Good luck!

Al Williams
AWC
Stamp Prototyping Board
http://www.awce.com/asp3.htm

·

ice-egoz

So for this, I will need to write a program for the Stamp. I need to come out with a simple SMS program. Im using a wavecom GSM modem. What are the implications that i have to take care so that the SMS program will run smoothly? Ive tried b4 but its still not working. I want to make a simple one. Therefore Im using just the DEBUG function.It shud work ryte? Does it send out the data to the modem?

'{$STAMP BS2p}
· PAUSE 250
· DEBUG "AT+IFC"······························· 'do I NEED TO SPECIFY WHETHER THE MODEM IS HARDWARE?
· DEBUG 61
· DEBUG "0,0"
· DEBUG CR
· PAUSE 2000
· DEBUG "AT"
· DEBUG CR
· PAUSE 2000
· DEBUG "AT+CSCA"···················· ·'this is the SMSC number of the SIM card inside the modem
· DEBUG 61
· DEBUG "98540020"
· DEBUG CR
· PAUSE 3000
· DEBUG "AT+CMGF"·············· 'Making sure that the GSM module is in text mode.
· DEBUG 61······················ 'ASCII Equivalent for =
· DEBUG "1"
· DEBUG CR···················· ' Carraige Return ot 'Enter'
· PAUSE 3000
· DEBUG "AT+CMGS"········· 'this is to send·an SMS
· DEBUG 61······················ 'ASCII Equivalent for =
· DEBUG "+6597375633"
· DEBUG CR
· PAUSE 4000
· DEBUG "KOPILA HERE"
· DEBUG 26·················· 'equivalent to ctrl-z, to end
· DEBUG CR
· PAUSE 2000
END

Will this even work? do i have to worry abt the electronics part? The power supply?

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I need all ya guidance Masters. [noparse]:)[/noparse]