vsergeev vsergeev
Audio echo effect. See http://dev.frozeneskimo.com/embedded_projects/audio_echo_effect for more info!
Revision 0:97643e5b2d5e, committed 2010-03-28
- Comitter:
- vsergeev
- Date:
- Sun Mar 28 11:23:11 2010 +0000
- Commit message:
Changed in this revision
| main.cpp | Show annotated file Show diff for this revision Revisions of this file |
| mbed.bld | Show annotated file Show diff for this revision Revisions of this file |
--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/main.cpp Sun Mar 28 11:23:11 2010 +0000
@@ -0,0 +1,50 @@
+#include "mbed.h"
+
+#define MAX_DELAY 15000
+#define MIN_DELAY 50
+
+#define MAX_GAIN 25
+#define MIN_GAIN 2
+
+/* ADC for the microphone/input, DAC for the speaker/output */
+AnalogIn mic(p19);
+AnalogOut speaker(p18);
+/* Two potentiometer voltage dividers for the delay/gain control knobs */
+AnalogIn delay_knob(p15);
+AnalogIn gain_knob(p16);
+
+unsigned short buffer[MAX_DELAY];
+
+/* inv_gain = 1 / gain; it's faster to avoid floating point during the main loop */
+int inv_gain = 3;
+int delay = MAX_DELAY;
+
+void read_knobs(void) {
+ delay = delay_knob*MAX_DELAY;
+ //gain = gain_knob*MAX_GAIN;
+ if (delay < MIN_DELAY)
+ delay = MIN_DELAY;
+ /*if (gain < MIN_GAIN)
+ gain = MIN_GAIN;
+ if (gain == MAX_GAIN)
+ gain -= 1;*/
+}
+
+int main() {
+ int i;
+ /* Fill up the sample buffer first */
+ for (i = 0; i < delay; i++)
+ buffer[i] += mic.read_u16();
+
+ for (i = 0; ; ) {
+ /* Multiply old data by the gain, add new data */
+ buffer[i] = buffer[i]/inv_gain + mic.read_u16();
+ /* Write to speaker */
+ speaker.write_u16(buffer[i]);
+ /* Increment index and wrap around, effectively only using "delay" length of the buffer */
+ i = (i+1) % delay;
+ /* Occasionally read the knobs */
+ if (i == 0)
+ read_knobs();
+ }
+}
\ No newline at end of file
--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/mbed.bld Sun Mar 28 11:23:11 2010 +0000 @@ -0,0 +1,1 @@ +http://mbed.org/users/mbed_official/code/mbed/builds/49a220cc26e0