Data Sheet

Copyright © Bridgetek Pte Ltd 30
BT81X (815/6) Advanced Embedded Video Engine Datasheet
Version 1.0
Document No.: BRT_000220 Clearance No.: BRT#126
4.6.4 Pins Drive Current Control
The output drive current of output pins can be changed as per the following table by writing to bit[6:2] of
REG_GPIO register or bit[14:10] of REG_GPIOX register. Alternatively, use the SPI command PINDRIVE
to change the individual pin drive strength.
REG_GPIO
Bit[6:5]
Bit[4]
Bit[3:2]
REG_GPIOX
Bit[14:13]
Bit[12]
Bit[11:10]
Value
00b#
01b
10b
11b
0b#
1b
00b#
01b
10b
11b
Drive
Current
5mA
10mA
15mA
20mA
1.2mA
2.4mA
5mA
10mA
15mA
20mA
Pins
GPIO0
GPIO1
GPIO2
GPIO3
CTP_RST_N
PCLK
DISP
VSYNC
HSYNC
DE
R7..R0
G7..G0
B7..B0
BACKLIGHT
MISO
MOSI
IO2
IO3
INT_N
Table 4-14 Output Drive Current Selection
Note: #Default value
4.7 Audio Engine
BT815/6 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.
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
Contin
uous
Pitch
adjust
Value
Effect
Contin
uous
Pitch
adjust
00h
Silence
Y
N
32h
DTMF 2
Y
N
01h
square wave
Y
Y
33h
DTMF 3
Y
N
02h
sine wave
Y
Y
34h
DTMF 4
Y
N
03h
sawtooth wave
Y
Y
35h
DTMF 5
Y
N