Tasking 8051-es fordito

[Dukai Zoltan]

TUSB6250 PDF-bol

After power-on reset is applied to the TUSB6250, the integrated MCU 
executes the bootloader program (also
referred as boot code) residing in the on-chip 8K byte ROM mapped to the 
MCU’s program memory space,
this process is also referred to as booting.
The major tasks of the boot code are:
1. To fetch the descriptors required for itself or the firmware to 
perform USB enumeration
2. Download the application firmware from one of the two external 
sources available during booting: one from
an external I2C EEPROM connected to the I2C interface of the TUSB6250 
and the other from the host
PC via the USB bus connection.
The MCU executes a read from an external I2C EEPROM and checks whether 
it contains the valid application
code by comparing the read value with the expected boot signature. If it 
contains the valid code, the MCU
executes follow-up reads from the EEPROM and writes the code into the 
TUSB6250’s internal 32K bytes of
default code RAM. If the external EEPROM does not contain any valid 
code, the MCU proceeds to boot from
the USB.
The I2C EEPROM normally is preprogrammed with the valid application code 
image. It also contains all the
configurable USB descriptors and other configurable descriptors or 
parameters for the mass storage device
connected to the TUSB6250’s ATA/ATAPI interface. For the option of 
booting from the USB host, the
application code may reside in the host PC. However, the _external_I2C_ 
EEPROM is _still_needed_ to store the
USB 2.0 specification required vendor ID and product ID specific to each 
individual end product manufacturer.

Tehat kell melle EEPROM.