Table of Contents
Advertisement
13.4.9.4 PROTOCOL FOR TERMINATION SIGNALS. The transfer protocol was defined
to avoid electrical contention on signals that can be driven by various sources. To do that, a
slave must not drive signals associated with the data transfer until the address phase is
completed and it recognizes the address as its own. The slave must disconnect from signals
immediately after it has acknowledged the cycle and no later than the termination of the next
address phase cycle. This indicates that the termination signals must be connected to power
through a pull-up resistor to avoid a situation in which a master samples an undefined value
in any of these signals when no real slave is addressed. See Figure 13-24 and
Figure 13-25 for more information.
Figure 13-24. Termination Signals Protocol Basic Connection
CLKOUT
A[6:31]
RD/WR
TSIZ[0:1]
TS
DATA
TA,BI,TEA
Figure 13-25. Termination Signals Protocol Timing Diagram
Freescale Semiconductor, Inc.
MPC823
SLAVE 1
SLAVE 1
SLAVE 1
NEGATES
ALLOWED TO
ACKNOWLEDGE
DRIVE
SIGNALS
ACKNOWLEDGE
SIGNALS
TURNS OFF
MPC823 REFERENCE MANUAL
For More Information On This Product,
Go to: www.freescale.com
EXTERNAL BUS
ACKNOWLEDGE/TERMINATION
SIGNALS (TA, TEA, BI)
SLAVE 2
SLAVE 2
SLAVE 2
SLAVE 2
NEGATES
ALLOWED TO
ACKNOWLEDGE
DRIVE
SIGNALS
ACKNOWLEDGE
AND
AND
SIGNALS
TURNS OFF
External Bus Interface
SLAVE 1
13-37
Advertisement
Table of Contents
