MC68MH360EM33L Freescale Semiconductor, MC68MH360EM33L Datasheet - Page 82

• Manufacturer Part Number: MC68MH360EM33L
• Description: IC MPU QUICC ETHER 33MHZ 240FQFP
• Manufacturer: Freescale Semiconductor

Specifications of MC68MH360EM33L

• Processor Type: M683xx 32-Bit
• Speed: 33MHz
• Voltage: 5V
• Mounting Type: Surface Mount
• Package / Case: 240-FQFP
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Features: -

Bus Operation
appropriate timing described in this section and in Section 10 Electrical Characteristics.
Additionally, BERR and HALT can be asserted together to indicate a retry termination. Refer
to 4.5 Bus Exception Control Cycles for additional information on the use of these signals.
See the memory controller description in Section 6 System Integration Module (SIM60) for
precautions about asserting BERR externally too early during DRAM and SRAM cycles con-
trolled by the memory controller.
The internal bus monitor can be used to generate the BERR signal for internal and external
transfers in all the following descriptions.
4.1.9.3 AUTOVECTOR (AVEC). This signal can be used to terminate interrupt acknowl-
edge cycles, indicating that the QUICC should internally generate a vector (autovector)
number to locate an interrupt handler routine. AVEC can be generated either externally or
internally by the SIM60 (refer to Section 6 System Integration Module (SIM60) for additional
information). AVEC is ignored during all other bus cycles.
4.2 DATA TRANSFER MECHANISM
The QUICC supports byte, word, and long-word operands, allowing access to 8-,16-, and
32-bit data ports through the use of asynchronous cycles controlled by DSACK1 and
DSACK0. The QUICC also supports byte, word, and long-word operands, allowing access
to 8-, 16, and 32-bit data ports through the use of synchronous cycles controlled by the fast-
termination capability of the SIM60.
4.2.1 Dynamic Bus Sizing
The QUICC dynamically interprets the port size of the addressed device during each bus
cycle, allowing operand transfers to or from 8-, 16-, and 32-bit ports. During an operand
transfer cycle, the slave device signals its port size (byte, word, or long word) and indicates
completion of the bus cycle to the QUICC through the use of the DSACKx inputs. Refer to
Table 4-2 for DSACKx encoding.
For example, if the QUICC is executing an instruction that reads a long-word operand from
a long-word aligned address, it attempts to read 32 bits during the first bus cycle. (Refer to
4.2.2 Misaligned Operands for the case of a word or byte address.) If the port responds that
it is 32 bits wide, the QUICC latches all 32 bits of data and continues with the next operation.
If the port responds that it is 16 bits wide, the QUICC latches the 16 bits of valid data and
runs another bus cycle to obtain the other 16 bits. The operation for an 8-bit port is similar,
but requires four read cycles. The addressed device uses the DSACKx signals to indicate
4-6
DSACK1
1
1
0
0
Freescale Semiconductor, Inc.
For More Information On This Product,
DSACK0
Table 4-2. DSACKx Encoding
1
0
1
0
MC68360 USER’S MANUAL
Go to: www.freescale.com
Insert Wait States in Current Bus Cycle
Complete Cycle—Data Bus Port Size is 8 Bits
Complete Cycle—Data Bus Port Size is 16 Bits
Complete Cycle—Data Bus Port Size is 32 Bits
Result
MOTOROLA