VS1000
6
VS1000 FUNCTIONAL BLOCKS
SPI
A synchronous serial port peripheral is used for SPIEEPROM boot, and can be used to access
other SPI peripherals (for example LCD or SED) by using another chip select. The SPI is only
used for boot if the XCS pin has a high level after reset (pull-up resistor attached). These pins
can also be used for general-purpose I/O when the SPI is not required.
The default player uses SI and SO for LED outputs.
NAND FLASH Interface
The NAND FLASH peripheral calculates a simple error-correcting code (ECC), and automates
some of the communication with a NAND FLASH chip. The firmware uses the peripheral to
access both small-page (512+16 B pages) and large-page (2048+64 B pages) NAND FLASH
chips. The first sector in the FLASH tells the firmware how it should be accessed.
The NAND FLASH interface pins can also be used as general-purpose I/O. The default firmware
uses GPIO0_[4:0] for keys, and GPIO0_[7:6] for other purposes. Pull-up and pull-down resis-
tors must be used for these connections so that the data transfer to and from the NAND FLASH
isn’t disturbed when keys are pressed.
USB
The USB peripheral handles USB 1.1 Full Speed harware protocol. Low speed communication
is not supported, but is correctly ignored. The USBP pin has a software-controllable 1.5kΩ
pull-up.
A control endpoint (1 IN and 1 OUT) and upto 6 other endpoints (3 IN and 3 OUT) can be
used simultaneously. Bulk, interrupt, and isochronous transfer modes are selectable for each
endpoint. USB receive from USB host to device (OUT) uses a 2 KiB buffer, thus allowing very
high transfer speeds. USB transmit from device to USB host (IN) also uses a 2 KiB buffer and
allows all IN endpoints to be ready to transmit simultaneously. Double-buffering is also possible,
but not usually required.
The firmware uses the USB peripheral to implement both USB Mass Storage Device and USB
Audio Device. Which device is activated depends on the state of GPIO0_6 when the USB
connection is detected. If GPIO0_6 has a pull-up resistor, VS1000 appears as an USB Au-
dio Device. If GPIO0_6 has a pull-down resistor, VS1000 appears as an USB Mass Storage
Device.
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.
Version: 1.4, 2011-10-06
14
ETC [ ETC ]
