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PEB 20321
PEF 20321
Local Bus Interface (LBI)
Data Sheet
148
2001-02-14
Figure 57
LBI Mailbox Structure
Note: The Mailbox registers should only be used for communication between the PCI
host system and an intelligent LBI peripheral.
The Mailbox Command Register provides the PCI/LBI Mailbox registers exclusive
access bit INPCI/INLBI and 15 bits for user defined interrupt information (refer to
Section 11.2.7
). It may for example perform the following functions:
interrupt generation,
deassertion of the LINTO interrupt signal by the intelligent LBI peripheral,
end-of-data-transfer indication, and
end-of-transaction indication.
Note that an intelligent LBI peripheral will deassert the LINTO interrupt signal by reading
Mailbox Command Register MBCMD, while the PCI host system will deassert the PCI
INTA interrupt signal by writing a
‘
1
’
to the MBI bit field in Status Acknowledge Register
STACK.
When a mailbox interrupt from LBI peripheral is detected, the LBI Mailbox Interrupt
Vector is generated and written to the host memory address specified in Peripheral
Interrupt Queue Base Address (PIQBA) register.
Note that an interrupt vector is generated after a write access to bit field INPCI/ INLBI of
MBCMD, even when this bit has not been reset between two write accesses.
The structure of the LBI Mailbox interrupt vector is as follows:
Mailbox Command Register
INPCI
Mailbox Data Register 7
Mailbox Data Register 6
Mailbox Data Register 5
Mailbox Data Register 4
Mailbox Data Register 3
Mailbox Data Register 2
Mailbox Data Register 1
E0
E4
E8
EC
F0
F4
F8
FC
15
0
8
7
Access from PCI host interface
1
Mailbox Data Register 1
Mailbox Command Register
0
INLBI
Access from LBI peripheral
8
7
4
2
3
5
6
15
Mailbox Data Register 7
Mailbox Data Register 6
Mailbox Data Register 5
Mailbox Data Register 4
Mailbox Data Register 3
Mailbox Data Register 2
7
0
ITD10347