jim hamblen
/
flash_audio_player_8bit
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Fork of
flash_audio_player
by 
jim hamblen
main.cpp@1:bd7bef7df00b, 2017-10-22 (annotated)
- Committer:
- 4180_1
- Date:
- Sun Oct 22 16:12:03 2017 +0000
- Revision:
- 1:bd7bef7df00b
- Parent:
- 0:e4f991474a45
ver 1.0
Who changed what in which revision?
| User | Revision | Line number | New contents of line |
|---|---|---|---|
| 4180_1 | 0:e4f991474a45 | 1 | #include "mbed.h" |
| 4180_1 | 0:e4f991474a45 | 2 | AnalogOut speaker(p18); |
| 4180_1 | 0:e4f991474a45 | 3 | Ticker sampletick; |
| 4180_1 | 0:e4f991474a45 | 4 | DigitalOut myled(LED1); |
| 4180_1 | 0:e4f991474a45 | 5 | //Plays Audio Clip using Array in Flash |
| 4180_1 | 1:bd7bef7df00b | 6 | //8-bit audio samples used |
| 4180_1 | 0:e4f991474a45 | 7 | //setup const array in flash with audio values |
| 4180_1 | 0:e4f991474a45 | 8 | //from free wav file conversion tool at |
| 4180_1 | 0:e4f991474a45 | 9 | //http://ccgi.cjseymour.plus.com/wavtocode/wavtocode.htm |
| 4180_1 | 0:e4f991474a45 | 10 | //see https://os.mbed.com/users/4180_1/notebook/using-flash-to-play-audio-clips/ |
| 4180_1 | 1:bd7bef7df00b | 11 | #include "cylon8bit.h" |
| 4180_1 | 0:e4f991474a45 | 12 | |
| 4180_1 | 0:e4f991474a45 | 13 | #define sample_freq 11025.0 |
| 4180_1 | 0:e4f991474a45 | 14 | //get and set the frequency from wav conversion tool GUI |
| 4180_1 | 0:e4f991474a45 | 15 | int i=0; |
| 4180_1 | 0:e4f991474a45 | 16 | |
| 4180_1 | 1:bd7bef7df00b | 17 | union short_or_char { |
| 4180_1 | 1:bd7bef7df00b | 18 | short s; |
| 4180_1 | 1:bd7bef7df00b | 19 | char c[2]; |
| 4180_1 | 1:bd7bef7df00b | 20 | }; |
| 4180_1 | 1:bd7bef7df00b | 21 | |
| 4180_1 | 1:bd7bef7df00b | 22 | union short_or_char sample; |
| 4180_1 | 1:bd7bef7df00b | 23 | |
| 4180_1 | 1:bd7bef7df00b | 24 | |
| 4180_1 | 0:e4f991474a45 | 25 | //interrupt routine to play next audio sample from array in flash |
| 4180_1 | 0:e4f991474a45 | 26 | void audio_sample () |
| 4180_1 | 0:e4f991474a45 | 27 | { |
| 4180_1 | 1:bd7bef7df00b | 28 | sample.c[1] = sound_data[i]; |
| 4180_1 | 1:bd7bef7df00b | 29 | speaker.write_u16(sample.s); |
| 4180_1 | 0:e4f991474a45 | 30 | i++; |
| 4180_1 | 0:e4f991474a45 | 31 | if (i>= NUM_ELEMENTS) { |
| 4180_1 | 0:e4f991474a45 | 32 | i = 0; |
| 4180_1 | 0:e4f991474a45 | 33 | sampletick.detach(); |
| 4180_1 | 0:e4f991474a45 | 34 | myled = 0; |
| 4180_1 | 0:e4f991474a45 | 35 | } |
| 4180_1 | 0:e4f991474a45 | 36 | } |
| 4180_1 | 0:e4f991474a45 | 37 | int main() |
| 4180_1 | 0:e4f991474a45 | 38 | { |
| 4180_1 | 1:bd7bef7df00b | 39 | sample.c[0] = 0; //setup fast byte to short conversion using union |
| 4180_1 | 0:e4f991474a45 | 40 | while(1) { |
| 4180_1 | 0:e4f991474a45 | 41 | myled = 1; |
| 4180_1 | 0:e4f991474a45 | 42 | //use a ticker to play send next audio sample value to D/A |
| 4180_1 | 0:e4f991474a45 | 43 | sampletick.attach(&audio_sample, 1.0 / sample_freq); |
| 4180_1 | 0:e4f991474a45 | 44 | //can do other things while audio plays with timer interrupts |
| 4180_1 | 0:e4f991474a45 | 45 | wait(10.0); |
| 4180_1 | 0:e4f991474a45 | 46 | } |
| 4180_1 | 0:e4f991474a45 | 47 | } |