Specifications
ARM DUI 0447J
Copyright © 2009-2014, ARM. All rights reserved.
B-4
ID052914
Non-Confidential
B.1.3
SMB asynchronous read
Figure B-3
shows the asynchronous read timing.
Figure B-3 Asynchronous read timing
The intervals are as follows:
•
Tsmbis
= 6ns
•
Tsmbov
= 7.5ns
•
Tsmboh
=
Tperiod
/2
•
Tsmbfov
= 6ns
•
Tsmbfis
= 6ns
All SMB input signals are registered on the rising edge of
SMB_CLKO
. They are then
registered a second time before being output on the IOFPGA SMB bus. This adds 1.5 clock
cycles of latency.
All IOFPGA SMB input signals are registered on the rising edge of
SMB_CLKO
. They are
then registered a second time before being output to the SMB bus. This adds 2 clock cycles of
latency.
An asynchronous read has a penalty of 1.5 clock cycles for the control signals to leave the IO
FPGA and an additional 2 clocks for the read data to be passed back. The total delay is 3.5 clock
cycles.
B.1.4
SMB asynchronous write
Figure B-4 on page B-5
shows the asynchronous write timing.
RDATA
SMB_DATA
SMB_nOE
SMB_nCS
SMB_ADDR
ADDR
SMB_CLKO
SMB_nCSreg_in
SMBF_nCS
RDATA
SMBF_DATA
RDATA
SMBF_DATAreg_in
RDATA
SMB_DATAinternal
SMBF_nOE
Tsmb
is
Trc
Tsmb
is
Tsmb
ov
Tsmb
ov
Tsmbf
is
Tsmb
ov
Tsmb
oh