MPC555CME Freescale Semiconductor, MPC555CME Datasheet - Page 328

• Manufacturer Part Number: MPC555CME
• Description: KIT EVALUATION FOR MPC555
• Manufacturer: Freescale Semiconductor
• Type: Microcontrollerr

Specifications of MPC555CME

• Contents: Module Board, Installation Guide, Power Supply, Cable, Software and more
• Processor To Be Evaluated: MPC555
• Data Bus Width: 32 bit
• Interface Type: RS-232
• For Use With/related Products: MPC555
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

9.5.6.2 Bus Grant
9.5.6.3 Bus Busy
MPC555
USER’S MANUAL
The arbiter asserts BG to indicate that the bus is granted to the requesting device. This
signal can be negated following the negation of BR or kept asserted for the current
master to park the bus.
When configured for external central arbitration, BG is an input signal to the MPC555
/ MPC556 from the external arbiter. When the internal on-chip arbiter is used, this sig-
nal is an output from the internal arbiter to the external bus master.
BB assertion indicates that the current bus master is using the bus. New masters
should not begin transfer until this signal is negated. The bus owner should not relin-
quish or negate this signal until the transfer is complete. To avoid contention on the
BB line, the master should three-state this signal when it gets a logical one value. This
requires the connection of an external pull-up resistor to ensure that a master that ac-
quires the bus is able to recognize the BB line negated, regardless of how many cycles
have passed since the previous master relinquished the bus. Refer to
/
MPC556
MPC555
Figure 9-24 Masters Signals Basic Connection
EXTERNAL BUS INTERFACE
Rev. 15 October 2000
External Bus
TS
BB
Slave 2
Figure
MOTOROLA
Master
9-24.
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