VS2000 Datasheet, PDF (14/21 Pages) List of Unclassifed Manufacturers – Headtracking Multichannel USB Audio Headphone IC / USB DAC

VLSI
Solution ^y
VS2000 PRELIMINARY
VS2000
6. FIRMWARE OPERATION
6.1 SPI Boot
The first boot method is SPI EEPROM. If GPIO1[0] is low after reset, SPI boot is skipped. If GPIO1[0] is high, it
is assumed to have a pull-up resistor and SPI boot is tried.
First the first four bytes of the SPI EEPROM are read using 16-bit address. If the bytes are “VLSI”, a 16-bit
EEPROM is assumed and the boot continues. If the last 3 bytes are read as “VLS”, a 24-bit EEPROM is assumed
and boot continues in 24-bit mode. Both 16-bit and 24-bit EEPROM should have the “VLSI” string starting at
address 0, and the rest of the boot data starting at address 4. If the identification is not found, SPI EEPROM boot
is skipped.
Boot records are read from EEPROM until an execute record is reached. Unknown records are skipped using the
data length field.
Byte Description
0
type 0=I-mem 1=X-mem 2=Y-mem 3=execute
1,2 data len lo, hi – data length in bytes
3, 4 address lo, hi – record address
5.. data*
6.2 UART Boot/Monitor
When byte 0xef is sent to RX at 115200 bps, the firmware enters monitor mode and communicates with vs3emu.
Memory contents can be displayed, executables can be loaded and run, or the firmware code can be restarted or
continued.
The UART is also a convenient way to program or reprogram the SPI EEPROM.
Version 0.3, 2007-09-05
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