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13. I2C Registers > Register Descriptions
430
Tsi574 User Manual
June 6, 2016
Integrated Device Technology
www.idt.com
09:15
BOOT_ADDR
Boot Device Address
This is the device address that the Tsi574 will access during
the boot load sequence. The least significant two bits [14:15]
of this field are latched at power-up from the state of the
I2C_SA[1:0] pins. This allows board configuration of up to
four unique Tsi574 devices on the I2C bus, each of which
access a different EEPROM during boot load. These two
bits are then locked for writing until the BUNLK bit is set to 1
during a write. This feature allows the boot load process to
change the boot address value to this register without
changing the power-up latch field.
This field can be changed during the boot load in
conjunction with setting the CHAIN bit, in order to jump the
boot load to a new boot device. This starting address is
copied internally at boot start or boot load, and it is the
internal value that is incremented, as explained in the BINC
field.
R/W
Undefined
16:18
PAGE_MODE
Page Mode
000 = 8 bytes
001 = 32 bytes
010 = 64 bytes
011 = 128 bytes
100 = 256 bytes
101 = 512 bytes
110 = 1024 bytes
111 = Infinite
This field modifies the boot load process to adjust the
boundary at which the boot device is re-addressed. In the
default case, the boot load sequence reads 8 bytes, then
does a Restart followed by the device and peripheral
address phases. By changing this field, the device will be
re-addressed only when the peripheral address crosses the
indicated boundary, thus saving a considerable number of
clock cycles during the boot. It is up to the programmer of
the EEPROM to ensure that the addressed device can
support consecutive reads up to the selected boundary.
Some devices wrap at certain page boundaries, and this
setting must be consistent with such limitations.
A setting of 111 causes the entire boot load to be read
sequentially, with two exceptions. No matter what the setting
of this field, if the boot address is incremented due to the
BINC mode being enabled, or if chaining occurs, then the
device is readdressed.
Changing this field during boot load will immediately affect
the boot sequence.
R/W
000
(Continued)
Bits
Name
Description
Type
Reset
Value