I've got some code running, using a 1284P to allow 13 push buttons and have 13 tones out.
(piezo thread elsewhere got me going on this)
(easily scaled back to 8 & 8 on an UNO).
It's sort of "ultimate blink without delay" if you will.
What I am seeing is long bursts of ~40KHz output for as long as 11 seconds before the output settles down to the intended frequency.
I was thinking that it is taking a long time for the equivalent of "previousMicros" to catch up & get back in sync with the intended frequency.
Any thoughts on how to fix that?
This is the code that oscillates:
/* Check if key for note C4 is pressed, key0 */
if ((portDkeys & 0x04) == 0){ // key is pressed D2 -> A2
// see if time to change hi to lo, or lo to hi
if ( (currentTime - changeTime[0])>=noteArray[48]){ // <<< seems like the value in changeTime[0]
// <<< needs to catch up when a note starts
changeTime[0] = changeTime[0] + noteArray[48];
PINA=0x04; // toggle output bit
}
}
This didn't fix it, just stopped the output altogether
/* Check if key for note C4 is pressed, key0 */
if (keyActive[0] == 0){changeTime[0] = currentTime;}
if ((portDkeys & 0x04) == 0){ // key is pressed D2 -> A2
// see if time to change hi to lo, or lo to hi
if ( (currentTime - changeTime[0])>=noteArray[48]){
changeTime[0] = changeTime[0] + noteArray[48];
PINA=0x04; // toggle output bit
keyActive[0]=1;
}
}
else{keyActive[0]=0;}
if ((portDkeys & 0x04) == 0){ // key is pressed D2 -> A2
if (keyActive[0]==0){
keyActive[0] = 1;
changeTime[0] = currentTime;
}
// see if time to change hi to lo, or lo to hi
if ( (currentTime - changeTime[0])>=noteArray[48]){ // time for a period toggle?
changeTime[0] = changeTime[0] + noteArray[48]; // setup time for the next toggle
PINA=0x04; // write a 1 to PINx toggles an output bit - NickGammon to the rescue again!
}
}
else{keyActive[0] = 0;}
Completed code, pic of prototype, schematic.
(cap on the power supply rail didn't make it onto the schematic tho, nor did the FTDI module off to the side of the 1284 board)
I connected to an amplified computer speaker. The sounds do not interfere with each other at all. I only had 8 switches, so I connected c-d-e-f-g-a-b-c. Tried pressing up to all 8 at once, did not hear any frequency fluctuation at all. C4 and C5 sound good together, no "beat frequency at all, and also sounds very in tune with wife's baby grand piano.
I could see several of these to make up a keyboard with as many octaves as you want.
I used 26 of 32 IO, so add some more notes or use the extra pins for other effects to be written later.
Writing a logic one to PINxn toggles the value of PORTxn, independent on the value of DDRxn. Note that the SBI instruction can be used to toggle one single bit in a port.
(easily scaled back to 8 & 8 on an UNO). I cannot understand this. I've seen the youtube link. This sounds cool. Can I make use of the attached code in UNO? I have another bare ATmtga32A.
Atmega1284 has 32 IO pins, so it can support 13 buttons and create 13 outputs (a full octave), and have some pins left for serial.
Uno has 20 pins, so you can't have quite as many. So the note just refers to having less buttons & less notes. Adjust the code for the hardware you have.
The schematic & picture is also followed for reference.
I powered up the system & pressed buttons & no sound.
Then I debugged the sketch to see if the port pin detection is working or not. using this code...
if ((portDkeys & 0x04) == 0){ // key is pressed D2 -> A2
if (keyActive[0]==0){
keyActive[0] = 1;
changeTime[0] = currentTime;
Serial.println("OK"); // added this line
}
Serial monitor prints the "OK" when I press a portD key, it means the controller is working. Now the second step, want to check if my speakers are working or not. I need your suggestion at this point. I am using a cheap pc stereo speaker 2.0 config. Connected the resistors in (One end is towards capacitor & the other ends are connected together). I put a 10K pot in the resistor node, as shown in pic & connected the wiper pin of the pot to the TIP of the stereo jack. Connected GND to the bottom part of the jack (Image included). Will this speaker work in this project? How to troubleshoot / setup the audio output part of this project? cant determine if any signal is generated from the output pins!
I'm using this speaker.
Oscilloscope handy to test output?
I also built this awesome project (pic attached) and after button/sound issues figured out that I needed to use the ATmegaBOOT_1284P_16MHz.hex bootloader file, after that it works great.
I used these for piano keys.
