Servo - March 2014

Listing 1.

Part 2: The Software

#include <SoftwareSerial.h> #define Rx 8 // Not used #define Tx 7 #define CTS  3 #define Q 2 #define nRESET 9
/* Soundgin commands */ #define ESC  0x1B // Required before every command #define PRESET 0x4B // Load a Sound into mixer A #define STOP  0x54  // Release mixer A #define VOICE 0x5B  // reset to voice parameters #define CLEAR 0x46  // Clear mixer A #define RAMP  0x47  // Ramp to targets A #define CLRALL 0x06 // Clear mixers A and B #define Q_ON  0x0E  // Use to note when phrase completed #define Q_OFF 0x0F  // as above... #define V_NOTE 0x08 // Set Voice to this note
SoftwareSerial soundgin(Rx,Tx); /** Setup gets everything going. */ void setup() {pinMode(Rx,INPUT); // Set up the soft serial port pinMode(Tx,OUTPUT); pinMode(nRESET, OUTPUT); HardReset(); // Reset the board hardware
 soundgin.begin(9600);
pinMode(CTS,INPUT); // Soundgin CTS handshake pinMode(Q,INPUT);  // Soundgin phrase done flag }

As I mentioned, I needed to go to Google to find any documentation on this board; again, I thank the folks at Babblebot.net for rescuing the only known documentation for the Soundgin before it was lost to humanity! This document gave me lots of details about the chip and how to connect to it. It left out many details about the preset sounds, how to do a software reset, and how to shift between voice and sound synthesis.

Once again, I resorted to our favorite search engine and found a couple of posts on Parallax Propeller and Parallax PBasic forums whose authors appeared to have "insider" information. I borrowed freely from these posts and I hope improved on them a little to format the Arduino code that I have now. Kudos go out to skf_wa on the forums.basic micro.com site and Haunted Programmer on the www.efx-tek.com forums site.

Figure 2 shows my project using a custom Arduino board that I have a bunch of in my toolbox. I made one change since I took the photo in Figure 2; I added a connection from IO- 9 on the Arduino to the reset pin on the Soundgin board, so I didn't need to manually reset the board on power-up.

Careful experimenting with these folk's examples showed that the Soundgin has some quirks, but you can get around them. The first revelation is that there appears to be a software reset that can be done by sending eight ESC (0x1B) characters to the chip. Not seven, not 10 — only eight will do the job. The second big revelation is that this reset sequence is the only certain way to stop a preset once it has been started that allows the voice settings to work immediately afterward.

Rather than bore on about how to control the Soundgin chip in text, I'll show the setup that I used and explain it. Listing 1 shows my definitions and setup function. I have a bunch of commands defined in my code that I am not using, but I did use all of them while

/* My phrases. */ unsigned char domo[] = {252, 203, 228, 223, 228, 252, 228, 232, 207, 210, 231, 239, 228, 252, 223, 214, 236, 239, 208, 252, 235, 228, 198, 230, 239, 228, 252, 0}; unsigned char baddog[]= {252, 197, 192, 205, 252, 203, 228, 211, 252, 0};
[…]
/** Speak the allophone string sent. Deal with handshaking as well */ void Speak(unsigned char *phrase)
 {int n;
 n=0; SendGin(Q_ON); while(phrase[n] != 0) { while(digitalRead(CTS) == 1); // wait for buffer to empty. soundgin.write(phrase[n]); n++; } // Clear Q and wait for the bit, meaning // phrase is done. SendGin(Q_OFF); while(digitalRead(Q) == 1); }