Texas Instruments TSB12LV26 - Manual (Page 24)

3–4
3.3 Device ID Register
The device ID register contains a value assigned to the TSB12LV26 by Texas Instruments. The device identification
for the TSB12LV26 is 8020h.
Bit 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
Name Device ID
Type R R R R R R R R R R R R R R R R
Default 1 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0
Register: Device ID
Type: Read-only
Offset: 02h
Default: 8020h
3.4 Command Register
The command register provides control over the TSB12LV26 interface to the PCI bus. All bit functions adhere to the
definitions in the
PCI Local Bus Specification, as seen in the bit descriptions of Table 3–3.
Bit 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
Name Command
Type R R R R R R R R/W R R/W R R/W R R/W R/W R
Default 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
Register: Command
Type: Read/Write, Read-only
Offset: 04h
Default: 0000h
Table 3–3. Command Register Description
BIT FIELD NAME TYPE DESCRIPTION
15–10 RSVD R Reserved. Bits 15–10 return 0s when read.
9 FBB_ENB R
Fast back-to-back enable. The TSB12LV26 does not generate fast back-to-back transactions, thus
this bit returns 0 when read.
8 SERR_ENB R/W
PCI_SERR enable. When this bit is set, the TSB12LV26 PCI_SERR driver is enabled. PCI_SERR can
be asserted after detecting an address parity error on the PCI bus.
7 STEP_ENB R
Address/data stepping control. The TSB12LV26 does not support address/data stepping, thus this bit
is hardwired to 0.
6 PERR_ENB R/W
Parity error enable. When this bit is set, the TSB12LV26 is enabled to drive PCI_PERR response to
parity errors through the PCI_PERR signal.
5 VGA_ENB R
VGA palette snoop enable. The TSB12LV26 does not feature VGA palette snooping. This bit returns 0
when read.
4 MWI_ENB R/W
Memory write and invalidate enable. When this bit is set, the TSB12LV26 is enabled to generate MWI
PCI bus commands. If this bit is cleared, then the TSB12LV26 generates memory write commands
instead.
3 SPECIAL R
Special cycle enable. The TSB12LV26 function does not respond to special cycle transactions. This bit
returns 0 when read.
2 MASTER_ENB R/W Bus master enable. When this bit is set, the TSB12LV26 is enabled to initiate cycles on the PCI bus.
1 MEMORY_ENB R/W
Memory response enable. Setting this bit enables the TSB12LV26 to respond to memory cycles on the
PCI bus. This bit must be set to access OHCI registers.
0 IO_ENB R
I/O space enable. The TSB12LV26 does not implement any I/O mapped functionality; thus, this bit re-
turns 0 when read.