21150-AB

Manufacturer Part Number21150-AB
DescriptionCommunications, Transparent PCI-to-PCI Bridge
ManufacturerIntel Corporation
21150-AB datasheet
 


Specifications of 21150-AB

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Table 20. Device Number to IDSEL s_ad Pin Mapping
Device
p_ad<15:11>
Number
0h
00000
1h
00001
2h
00010
3h
00011
4h
00100
5h
00101
6h
00110
7h
00111
8h
01000
9h
01001
Ah
01010
Bh
01011
Ch
01100
Dh
01101
Eh
01110
Fh
01111
10H–1Eh
10000–11110
1Fh
1111
The 21150 can assert up to 16 unique address lines to be used as IDSEL signals for up to 16 devices
on the secondary bus, for device numbers ranging from 0 through 15. Because of electrical loading
constraints of the PCI bus, more than 16 IDSEL signals should not be necessary. However, if
device numbers greater than 15 are desired, some external method of generating IDSEL lines must
be used, and no upper address bits are then asserted. The configuration transaction is still translated
and passed from the primary bus to the secondary bus. If no IDSEL pin is asserted to a secondary
device, the transaction ends in a master abort.
The 21150 forwards Type 1 to Type 0 configuration read or write transactions as delayed
transactions. Type 1 to Type 0 configuration read or write transactions are limited to a single 32-bit
data transfer.
4.7.3
Type 1 to Type 1 Forwarding
Type 1 to Type 1 transaction forwarding provides a hierarchical configuration mechanism when
two or more levels of PCI-to-PCI bridges are used.
When the 21150 detects a Type 1 configuration transaction intended for a PCI bus downstream
from the secondary bus, the 21150 forwards the transaction unchanged to the secondary bus.
Ultimately, this transaction is translated to a Type 0 configuration command or to a special cycle
transaction by a downstream PCI-to-PCI bridge. Downstream Type 1 to Type 1 forwarding occurs
when the following conditions are met during the address phase:
The low 2 address bits are equal to 01b.
Preliminary
Datasheet
Secondary IDSEL s_ad<31:16>
0000 0000 0000 0001
0000 0000 0000 0010
0000 0000 0000 0100
0000 0000 0000 1000
0000 0000 0001 0000
0000 0000 0010 0000
0000 0000 0100 0000
0000 0000 1000 0000
0000 0001 0000 0000
0000 0010 0000 0000
0000 0100 0000 0000
0000 1000 0000 0000
0001 000 0000 0000
0010 0000 0000 0000
0100 0000 0000 0000
1000 000 0000 0000
0000 0000 0000 0000
Generate special cycle (p_ad<7:2> = 00h)
0000 0000 0000 0000 (p_ad<7:2>
00h)
21150
s_ad Bit
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