Resets
2-23
As indicated in the table, the serial ROM chip address mapping is
equivalent to the power-on value of signal pins A[10:8].
2.7.4 Download Port Select
The A11 pin selects which of the Two-Wire Serial interfaces will perform
the initial download. The default for the download is Two-Wire Serial
port 0. A pull-up resistor on the A11 pin starts the download from Two-
Wire Serial port 1, after a reset or at power-on.
2.8 Resets
The SYM53C040 can be reset in three different ways: power-on reset,
asserting the reset pin, and an internal chip reset forced by expiration of
the watchdog timer. A power-on reset initializes all chip registers to their
default values and returns the Two-Wire Serial port and the SCSI or
SFF-8067 interfaces to idle states. A power-on reset is caused when
power to the chip has been turned off and is turned back on. Manually
asserting the RESET/ pin triggers a soft reset. This can be done to
initiate a second configuration ROM download for the purpose of adding
more firmware or changing default register values before the chip begins
normal operation.
If the watchdog timer is used and it expires, it causes an internal soft
reset. If the Enable Reset Output bit is also set (0xFF05, bit 7), the
Table 2.4
Serial ROM Chip Addresses
Serial ROM Chip Address
AD10 Pull-up
AD9 Pull-up
AD8 Pull-up
1010 000
None
None
None
1010 001
None
None
Pull-up
1010 010
None
Pull-up
None
1010 011
None
Pull-up
Pull-up
1010 100
Pull-up
None
None
1010 101
Pull-up
None
Pull-up
1010 110
Pull-up
Pull-up
None
1010 111
Pull-up
Pull-up
Pull-up
Содержание Symbios SYM53C040
Страница 12: ...xii Preface...
Страница 90: ...4 18 SCSI and DMA Registers...
Страница 98: ...5 8 SFF 8067 Registers...
Страница 110: ...6 12 Two Wire Serial Registers...
Страница 126: ...7 16 Miscellaneous Registers...
Страница 160: ...8 34 System Registers...
Страница 184: ...9 24 Electrical Characteristics...
Страница 194: ...A 10 Register Summary...
Страница 214: ......