SpeakJet Serial Interface

SN96

Hello Gents,

I have a new project I want to try. I have downloaded the SpeakJet users manual and it has a lot of information regarding its use. One thing that is unclear to me is the use of a DB9F connector. In the documentation it warns against the use of directly connecting a RS232 interface to the SpeakJet unless a MAX232 is used.

I have attached my schematic showing what I have so far except the DB9F connector is not connected to the SpeakJet in the schematic.

Another question is how to program the SpeakJet via the RS232 connector. Would the Stamp IDE work for this? Or, would a simple 2 wire stamp interface be better?

Thanks for any help.

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Mike





Post Edited (SN96) : 3/18/2006 2:38:26 AM GMT

Fe2o3Fish

Hey Mike,

There shouldn't be any problem using up the DB9F connector. This is quite appropriate
because a straight-thru serial cable from a PC will have a DB9 male on one end and a DB9
female connector on the other. The end of the cable that attaches to the PC's serial port
will be the DB9 female and thusly the end of the cable attaching to your SpeakJet (SJ) circuit
wil be the DB9 male connector. Naturally, you'll want a DB9 female connector on your SJ
to accept the DB9 male end of your connecting cable.

If you're going to be connecting your SJ directly to a Basic Stamp (pins 0-15) instead of
serial/RS-232 port on a PC then you will not be needing the MAX232. The MAX232 chip
converts the -12 to +12 volt states, used in RS-232, to +5 to 0 volt states used by the
Basic Stamp on pins 0 to 15 (technically called TTL level serial). BTW, the DS275 chip
can accomplish the same task but with no extra components.

The SpeakJet's RX/TX pins use or need to see TTL level serial signals. RS-232 levels can
(and probably will be) too much for the SJ to handle directly. Please heed the warnings.
A DS275 is a good chip that has been used with a SJ before. The only lines needing conversion
are the RX input on the SJ and the D2 output from the SJ. The SJ doesn't have a TX pin
since it transmits nothing back to the connected "host". The D2 output is used as hardware
flow-control. These are the only two pins need to connect the SJ to a CPU.

Your second question I'm not sure about in that your really don't "program" a SJ like you
would a Basic Stamp. As an aside, you can store sequences of SJ commends and sounds
and have them played upon a rising or falling signal on the SJ's Event Input pins 1-4 & 6-9.
Other than that, the SJ simply acts upon commands sent serially onto pin 10. A program
call PhraseALator (google "speakjet phrasealator") is useful for programming the EEPROM
and testing word pronounciation and sound generation although using the commands in the
SpeakJet documentation can accomplish the same thing including programming the
speech/sounds associated with the Event Input pins. Oh, the Stamp IDE will not work
for this although a properly programmed Stamp can send the proper codes to the SJ.

Please don't hesitate to ask if you need further help!

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-Rusty-
--
Rusty Haddock = KD4WLZ = rusty@fe2o3.lonestar.org
**Out yonder in the Van Alstyne (TX) Metropolitan Area**
Microsoft is to software what McDonalds is to gourmet cooking

SN96

Thanks Fe2o3Fish,

You clarified all my questions. Since the SJ will work via TTL level serial lines from the stamp, I am not going to worry about using an RS232 interface. I was not sure due to the carrier board sold on this website has a RS232 interface connector which is why I wanted to ask if it was needed.

Thanks again for your valuable knowledge!

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Mike



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