Getting started with the Speakjet

[russbow]

the speakjet is an 18 pin audio synthesiser chip that interfaces with the Picaxe well.

Unfortunately it is not plug n play and an interface board is needed to just experiment with the software.

I have produced a board that enables me to program the Speakjet and then to use it as an interface to any Picaxe.

Note I have confined myself to "events" prompted by Picaxe outputs and have ignored the "on the fly" capabilities. To be honest, I see no point in them.

The exercise is in two parts. Part one is the hardware interface, part 2 is using the software to program the Speakjet.

I attach a PDF for part one.

I am going to bag post #2 of this thread for the software bit that may take a day or two to complete.

Russ

 

[russbow]

This is an overview of the Speakjet software.

It does not cover all the facilities of the chip, but certainly will enable you to get things working.



R.

 

[Andres Rodriguez]

Fantastic job Russ.
Thank you for sharing.
Andres

 

[westaust55]

Great to see others putting some effort into producing basic tutorial like documents for PICAXE projects.

Well done and now waiting the software side.

With respect to your serin type interface, with the microMega PFU chips I have like yourself used a Rev Ed style programming interface (the Enhanced version) and included the BAT85 diode to limit the negative going voltage where a PC serial interface is used rather than rely upon the diodes within the actual chip being programmed. Also needed a 7406 to reverse the polarity of the PC serial comms signals for the uMFPU. presume that is why you have the transistor.

final note (and we all make them ) a typo or two on the the first page:

"Depending on the program, taking a pi either high or low will instigate a stored phrase."
The word "pin" is missing the "n"

"Please note it is a TOP view of the bord,"
missing the "a" in board.


EDIT: I can add an extra device to my DIPTRACE library (and even PEBBLE) for the SPEAKJET chip
If you want some help to prepare a schematic send me a PM.

 

[russbow]

I have edited post #1 because the baud rate was wrong in the PDF.

( corrected the typos as well Westy )

I have added the part 2 PDF to post #2

Russ

 

[westaust55]

@Russ,
Looks good and well done to publish this tutorial.

Reading how the editor works, while there are enhancements, in terms of the basic text to speech encoding it is similar to what I did around 30 years ago with the VOTRAX SC-01 speech synthesis chip and phomenes. Did not have a nice editor in those days but wrote 6502 machine code “wedges” into BASIC on a OSI C2-4P and later a C-64 using the US Naval Research Labs work/rules of the time to convert text to the sounds/phonemes. The quality was however far improved by the incusion of an exceptions dictionary to the extent that the exceptions dictionary took up around 90 percent of the total machine code space. In machine code and using inteerrupts BASIC programs could time slcie and be talking and displaying information on a screen seemingly simultaneously.

Obviously the PICAXE cannot do the text to speech conversions in "real time" but extended phases could be stored in external EEPROM and read in to be fed to the speakjet chip for more vocal interface with the user.

While I have an SPE-030 speech module, all this just might get me reminiscing further and interested to play with the Speakjet chip myself.

 

[Andres Rodriguez]

Thank you

Fantastic work Russ, thank you for taking the time to help others in the forum.
I had succeeded using a Max232 on a breadboard but the PCB was getting too big. I changed to your approach with a transistor (I used 2N2222 because it was available in my parts bin). By eliminating the MAX232 I was able to fit the amplifier in a board with the same dimensions.
It works great, my next step is to add words to the dictionary. And come up with a filter to eleminate the buzz I am getting on the speaker.
Andrés

 

[russbow]

Andres,good stuff. pity about the buzz. I don't get that problem. Do you get it if the vol control is backed fully off? If so, suspect audio lead Speakjet > amp. If not suspect supply / proximity to PC, strip lights etc. maybe even an earth loop.

R.

 

[Andres Rodriguez]

Andres,good stuff. pity about the buzz. I don't get that problem. Do you get it if the vol control is backed fully off? If so, suspect audio lead Speakjet > amp. If not suspect supply / proximity to PC, strip lights etc. maybe even an earth loop.

R.

I don't get it when the volume control is full off or almost full off.
I noticed a difference on the Amp circuit. You have C1 between R2 and ground. I placed C1 betwee Pin5 and R2. I am not sure if that is the problem but I will investigate.

 

[russbow]

Doubt if is anything to do with the output network. If it changes with you volume position, I suspect it is being picked up at the input.

These amps are very sensitive and it is easy to overdrive them. I think I would want to ensur proper signal level first.

There was a discussion about this on another thread >

http://www.picaxeforum.co.uk/showthread.php?t=15446&highlight=lm386&page=2

Particularly post #11

Easy way to chech your amp "quality" - plug it into the earphone socket of a walkman.