Hi,
I am trying to work on a Tardis project from Dr. Who. Basically I want to play the Tardis theme and have an LED brighten and dim while the Tardis Theme is playing. I have gotten the file and music to play correctly. In a separate sketch I have used timer 0 to brighten and dim the LED, which worked perfectly. When I put the codes together, however, only the light will work, and not the sound. The debug sketch in the library says it cannot initialize the card once I have my LED code in there.
Hopefully I am making sense. I will post my current code and explain what I am trying to do.
#include <SimpleSDAudio.h>
//Here I have set up an array of integers that start from zero and go to 255, and then decrease to 0. This is so I can brighten and dim an LED while the file is playing.
int array[]={0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31,32,33,34,35,36,37,38,39,40,41,42,43,44,45,46,47,48,49,50,51,52,53,54,55,56,57,58,59,60,61,62,63,64,65,66,67,68,69,70,71,72,73,74,75,76,77,78,79,80,81,82,83,84,85,86,87,88,89,90,91,92,93,94,95,96,97,98,99,100,101,102,103,104,105,106,107,108,109,110,111,112,113,114,115,116,117,118,119,120,121,122,123,124,125,126,127,128,129,130,131,132,133,134,135,136,137,138,139,140,141,142,143,144,145,146,147,148,149,150,151,152,153,154,155,156,157,158,159,160,161,162,163,164,165,166,167,168,169,170,171,172,173,174,175,176,177,178,179,180,181,182,183,184,185,186,187,188,189,190,191,192,193,194,195,196,197,198,199,200,201,202,203,204,205,206,207,208,209,210,211,212,213,214,215,216,217,218,219,220,221,222,223,224,225,226,227,228,229,230,231,232,233,234,235,236,237,238,239,240,241,242,243,244,245,246,247,248,249,250,251,252,253,254,255,255,254,253,252,251,250,249,248,247,246,245,244,243,242,241,240,239,238,237,236,235,234,233,232,231,230,229,228,227,226,225,224,223,222,221,220,219,218,217,216,215,214,213,212,211,210,209,208,207,206,205,204,203,202,201,200,199,198,197,196,195,194,193,192,191,190,189,188,187,186,185,184,183,182,181,180,179,178,177,176,175,174,173,172,171,170,169,168,167,166,165,164,163,162,161,160,159,158,157,156,155,154,153,152,151,150,149,148,147,146,145,144,143,142,141,140,139,138,137,136,135,134,133,132,131,130,129,128,127,126,125,124,123,122,121,120,119,118,117,116,115,114,113,112,111,110,109,108,107,106,105,104,103,102,101,100,99,98,97,96,95,94,93,92,91,90,89,88,87,86,85,84,83,82,81,80,79,78,77,76,75,74,73,72,71,70,69,68,67,66,65,64,63,62,61,60,59,58,57,56,55,54,53,52,51,50,49,48,47,46,45,44,43,42,41,40,39,38,37,36,35,34,33,32,31,30,29,28,27,26,25,24,23,22,21,20,19,18,17,16,15,14,13,12,11,10,9,8,7,6,5,4,3,2,1,0};
int y=0;
void setup()
{
pinMode (6, OUTPUT); //This is the OC0A pin that I want to use for the LED
cli();
TCCR0A = 0x83; //In the control registers, I have set fast PWM, non inverting mode. I used a prescaler of 256, so that every 4ms the OCR0B would match and set an interrupt.
//During the interrupt, I want to increment the element in the array. So every 4ms, the light brigthens slightly.
TCCR0B = 0x04;
OCR0A = 255;
OCR0B = 249;
TCNT0 = 0;
TIMSK0 = 0x04;
sei();
SdPlay.setSDCSPin(10); // Enable if your SD card CS-Pin is not at Pin 4...
SdPlay.init(SSDA_MODE_FULLRATE | SSDA_MODE_MONO | SSDA_MODE_AUTOWORKER);
SdPlay.setFile("EXAMPLE.AFM");
SdPlay.play();
}
void loop(void) {
}
ISR(TIMER0_COMPB_vect)
{
y++;
OCR0A = (array [y]);
if(y==512)
{
y=0;
}
}
This section of code:
#include <SimpleSDAudio.h>
void setup()
{
// SdPlay.setSDCSPin(10); // Enable if your SD card CS-Pin is not at Pin 4...
SdPlay.init(SSDA_MODE_FULLRATE | SSDA_MODE_MONO | SSDA_MODE_AUTOWORKER);
SdPlay.setFile("EXAMPLE.AFM");
SdPlay.play();
}
void loop(void) {
}
comes directly from the AbsoluteMinimum example in the simple sd audio library. The only things I added is the controls for timer 0 to run the light, and an interrupt service routine.
So to set up timer0, I set Bits 7:6 – COM0A1:0 in the timer 0 control register A (TCCR0A) to 1, 0, which is non inverting PWM for the OC0A pin. I set Bits 1:0 – WGM01:0: in the TCCR0A to 1, 1, which selects the fast PWM mode. All I did in the TCCR0B register was set the clock to a 256 prescaler.
The way I set it up, the OCR0A register holds the PWM value for the OC0A pin (pin 6 on the arduino). The OCR0B holds a value that will set an interrupt every 4ms. In this interrupt, I set the next PWM value that needs to be in the OCR0A register. So in summary, every 4 ms, the OCR0A register is set to the next integer in the array, and the array makes the PWM values increase to 255 and then decrease to 0. This way I get my brightening and dimming LED on pin 6.
So, the SD audio works fine on its own, and the LED works fine on its own. But when I try to combine the two, only the light works; I do not get any audio. So is my ISR taking too much time and ruining the audio? Or does the audio library use all the timers? Note: if I use the BareMinimumWithDebug example in the library, and insert my timer 0 code, it says the SD card will not initialize. I checked the CS pin too, so it has something to do with my timer setup.
I hope my code makes sense and that I have explained my problem well. If anybody could let me know what is wrong, and if there is a possible solution or better way to do this, I would greatly appreciate it.
Thanks,
Thomas Hooper