Monday, December 30, 2013

Mike's Speech Synthesizer (Part III)

          After extended review and tinkering I was able to cobble together a small circuit that I could use to send data to the Speakjet. Once again the datasheet was an absolute must have at this stage. Following the schematic closely is what lead to my ultimate success.

Simple Serial Interface
           For the initial test I did not use any flow control so I was limited in the amount of data I could send to the Speakjet at one time. To facilitate the serial data coming into the device, I used an FTDI USB to serial TTL level device. This is basically a serial port to the computer and would be configured as such at 9600 bps 8,N,1. This modest setup can be viewed below.

My Version

            I also added an O-Scope to monitor serial data coming out of the FTDI device.

              On the software side I used the Phrase-A-Lator software available at the Sparkfun website to test things out. This is a good piece of software to get you up and running. It also provides an excellent work environment to figure out what codes to send to make what words.
       Below is a small video I put together that demonstrates a successful test of the serial interface.

               Now that I was certain that I could successfully get data into and spoken by the Speakjet, it was time to tackle the flow control issue, so that large phrases could be spoken without any pause. This was as simple as hooking the Clear to Send (CTS) pin of the FTDI device up to the Buffer Half Full pin on the Speakjet.
Looks like Pin 15 to me

                Once that was complete, long phrases and even singing was achieved.

               Next on the list is to get a Text to Speech chip so that real words instead of codes can be submitted to the circuit. Also hooking things up to another type of computer.

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