Data Sheet

Copyright © Bridgetek Pte Ltd 32
BT81X (815/6) Advanced Embedded Video Engine Datasheet
Version 1.0
Document No.: BRT_000220 Clearance No.: BRT#126
43
G2
98.0
87
D#6
1244.5
44
G#2
103.8
88
E6
1318.5
45
A2
110.0
89
F6
1396.9
46
A#2
116.5
90
F#6
1480.0
47
B2
123.5
91
G6
1568.0
48
C3
130.8
92
G#6
1661.2
49
C#3
138.6
93
A6
1760.0
50
D3
146.8
94
A#6
1864.7
51
D#3
155.6
95
B6
1975.5
52
E3
164.8
96
C7
2093.0
53
F3
174.6
97
C#7
2217.5
54
F#3
185.0
98
D7
2349.3
55
G3
196.0
99
D#7
2489.0
56
G#3
207.7
100
E7
2637.0
57
A3
220.0
101
F7
2793.8
58
A#3
233.1
102
F#7
2960.0
59
B3
246.9
103
G7
3136.0
60
C4
261.6
104
G#7
3322.4
61
C#4
277.2
105
A7
3520.0
62
D4
293.7
106
A#7
3729.3
63
D#4
311.1
107
B7
3951.1
64
E4
329.6
108
C8
4186.0
Table 4-16 MIDI Note Effect
4.7.2 Audio Playback
The BT815/6 can play back recorded sound through its audio output. To do this, load the original sound
data into the BT815/6’s RAM, and set registers to start the playback.
The registers controlling audio playback are:
REG_PLAYBACK_START: the start address of the audio data
REG_PLAYBACK_LENGTH: the length of the audio data, in bytes
REG_PLAYBACK_FREQ: the playback sampling frequency, in Hz
REG_PLAYBACK_FORMAT: the playback format, one of LINEAR SAMPLES, uLAW
SAMPLES, or ADPCM SAMPLES
REG_PLAYBACK_LOOP: if zero, the sample is played once. If one, the sample is repeated
indefinitely
REG_PLAYBACK_PLAY: a write to this location triggers the start of audio playback,
regardless of writing ‘0’ or ‘1’. Read back ‘1’ when playback
is ongoing, and ‘0’ when playback finishes
REG_VOL_PB: playback volume, 0-255
The mono audio formats supported are 8-bits PCM, 8-bits uLAW and 4-bits IMA-ADPCM. For
ADPCM_SAMPLES, each sample is 4 bits, so two samples are packed per byte, the first sample is in bits
0-3 and the second is in bits 4-7.
The current audio playback read pointer can be queried by reading the REG_PLAYBACK_READPTR. Using
a large sample buffer, looping, and this read pointer, the host MPU/MCU can supply a continuous stream
of audio.