Datasheet

VS1053b Datasheet
9 FUNCTIONAL DESCRIPTION
9.6.3 SCI_BASS (RW)
Name Bits Description
ST_AMPLITUDE 15:12 Treble Control in 1.5 dB steps (-8..7, 0 = off)
ST_FREQLIMIT 11:8 Lower limit frequency in 1000 Hz steps (1..15)
SB_AMPLITUDE 7:4 Bass Enhancement in 1 dB steps (0..15, 0 = off)
SB_FREQLIMIT 3:0 Lower limit frequency in 10 Hz steps (2..15)
The Bass Enhancer VSBE is a powerful bass boosting DSP algorithm, which tries to take the
most out of the users earphones without causing clipping.
VSBE is activated when SB_AMPLITUDE is non-zero. SB_AMPLITUDE should be set to the
user’s preferences, and SB_FREQLIMIT to roughly 1.5 times the lowest frequency the user’s
audio system can reproduce. For example setting SCI_BASS to 0x00f6 will have 15 dB en-
hancement below 60 Hz. When the bass enhancer is in use with VS1053b, the bass portion is
calculated in mono.
Note: Because VSBE tries to avoid clipping, it gives the best bass boost with dynamical music
material, or when the playback volume is not set to maximum. It also does not create bass: the
source material must have some bass to begin with.
Treble Control VSTC is activated when ST_AMPLITUDE is non-zero. For example setting
SCI_BASS to 0x7a00 will have 10.5 dB treble enhancement at and above 10 kHz.
Bass Enhancer uses about 2.1 MIPS and Treble Control 1.2 MIPS at 44100 Hz samplerate.
Both can be on simultaneously.
In VS1053b bass and treble initialization and volume change is delayed until the next batch of
samples are sent to the audio FIFO. Thus, unlike with earlier VS10XX chips, audio interrupts
can no longer be missed when SCI_BASS or SCI_VOL is written to.
Version: 1.22, 2014-12-19 41