Data Sheet

VS1000 Datasheet
6 VS1000 FUNCTIONAL BLOCKS
6.3 Analog Section
The third regulator provides power for the analog section.
The analog section consists of digital to analog converters and earphone driver. This includes a
buffered common voltage generator (CBUF, around 1.2 V) that can be used as a virtual ground
for headphones.
The AVDD regulator output pin must be connected to AVDD1..AVDD3 pins with proper bypass
capacitors, because they are not connected internally.
The USB pins use the internal AVDD voltage, and the firmware configures AVDD to 3.6 V when
USB is attached.
Low AVDD voltage can be monitored by software. Currently the firmware does not take advan-
tage of this feature.
CBUF contains a short-circuit protection. It disconnects the CBUF driver if pin is shorted to
ground. In practise this only happens with external power regulation, because there is a limit to
how much power the internal regulators can provide.
6.3.1 Powering Up
In normal firmware operation the analog drivers are enabled only when the decoding of an
audio file is started.
If the analog drivers are enabled without starting audio decoding, it is possible for the analog
output to remain high or low until audio is output.
You can call the following function in your startup to force the outputs to the middle.
#include <vs1000.h>
#include <audio.h>
#include <string.h>
#include <player.h>
#include <codec.h>
#include <dev1000.h>
extern struct CodecServices cs;
void DACInit(void) {
cs.sampleRate = 48000U;
SetRate( (u_int16)cs.sampleRate );
memset(tmpBuf, 24000, sizeof(tmpBuf));
tmpBuf[7] = tmpBuf[6] = tmpBuf[3] = tmpBuf[2] = -24000;
audioPtr.wr = (audioPtr.rd = audioBuffer) + 4;
{
int i;
for (i=0;i<200;i++) {
AudioOutputSamples(tmpBuf, 4);
}
}
}
Version: 1.5, 2016-06-09 19