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BT817A Automotive Advanced Video Engine Datasheet

Version 1.0

Document No.: BRT_000251 Clearance No.: BRT#194

Pins

GPIO0

GPIO1

GPIO2

GPIO3

CTP_RST_N

PCLK

DISP

VSYNC

HSYNC

R7..R0

G7..G0

B7..B0

BACKLIGHT

MISO

MOSI

IO2

IO3

INT_N

SPIM_SCLK

SPIM_SS_N

SPIM_MOSI

SPIM_MISO

SPIM_IO2

SPIM_IO3

Table 4-16 Output Drive Current Selection

Note: #Default value

4.7 Audio Engine

BT817A provides mono audio output with sigma-delta modulation through a digital output pin,

AUDIO_L. It outputs two audio sources, the sound synthesizer and audio file playback.

4.7.1 Sound Synthesizer

A sound processor, AUDIO ENGINE, generates the sound effects from a small ROM library of waves

table. To play a sound effect listed in Table 4.3, load the REG_SOUND register with a code value and

write 1 to the REG_PLAY register. The REG_PLAY register reads 1 while the effect is playing and

returns a ‘0’ when the effect ends. Some sound effects play continuously until interrupted or

instructed to play the next sound effect. To interrupt an effect, write a new value to REG_SOUND and

REG_PLAY registers; e.g., write 0 (Silence) to REG_SOUND and 1 to PEG_PLAY to stop the sound

effect. Note that the audio engine will automatically start upon chip boot up, and the AUDIO_L pin will

output a carrier signal at a frequency equal to half of the system clock. To avoid the carrier wave

being output on the pin when audio is not used, play the mute sound (write 0x60 to REG_SOUND and

1 to REG_PLAY). The AUDIO_L pin will then output a logic low level.

The sound volume is controlled by register REG_VOL_SOUND. The 16-bit REG_SOUND register takes

an 8-bit sound in the low byte. For some sounds, marked "pitch adjust" in the table below, the high 8

bits contain a MIDI note value. For these sounds, a note value of zero indicates middle C. For other

sounds, the high byte of REG_SOUND is ignored.

Value

Effect

Conti

nuous

Pitch

adjus

Value

Effect

Conti

nuous

Pitch

adjus

00h

Silence

32h

DTMF 2

01h

square wave

33h

DTMF 3

02h

sine wave

34h

DTMF 4

03h

sawtooth wave

35h

DTMF 5

04h

triangle wave

36h

DTMF 6

05h

Beeping

37h

DTMF 7

06h

Alarm

38h

DTMF 8

07h

Warble

39h

DTMF 9

08h

Carousel

40h

harp

10h

1 short pip

41h

xylophone

11h

2 short pips

42h

tuba

12h

3 short pips

43h

glockenspiel

13h

4 short pips

44h

organ

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