MC68302EH16C Freescale Semiconductor, MC68302EH16C Datasheet - Page 117

• Manufacturer Part Number: MC68302EH16C
• Description: IC MPU MULTI-PROTOCOL 132-PQFP
• Manufacturer: Freescale Semiconductor

Specifications of MC68302EH16C

• Processor Type: M683xx 32-Bit
• Speed: 16MHz
• Voltage: 5V
• Mounting Type: Surface Mount
• Package / Case: 132-MQFP, 132-PQFP
• Controller Family/series: 68K
• Core Size: 32 Bit
• Ram Memory Size: 1152Byte
• Cpu Speed: 16MHz
• No. Of Timers: 3
• Embedded Interface Type: SCP, TDM
• Digital Ic Case Style: PQFP
• Rohs Compliant: Yes
• Family Name: M68000
• Device Core: ColdFire
• Device Core Size: 32b
• Frequency (max): 16MHz
• Instruction Set Architecture: RISC
• Supply Voltage 1 (typ): 5V
• Operating Temp Range: 0C to 70C
• Operating Temperature Classification: Commercial
• Mounting: Surface Mount
• Pin Count: 132
• Package Type: PQFP
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Features: -
• Lead Free Status / Rohs Status: RoHS Compliant part Electrostatic Device

to the DRAM bank. The PAL generates the RAS and CAS lines for the DRAM chips and con-
trols the address multiplexing in the external address buffers. One of the MC68000 chip-se-
lect lines can be used as the DRAM bank enable signal, if desired.
The refresh operation is a byte read operation. Thus, UDS or LDS will be asserted from the
MC68302, but not both. A refresh to an odd address will assert LDS; whereas, a refresh to
an even address will assert UDS.
3.10.2 DRAM Refresh Controller Bus Timing
The DRAM refresh controller bus cycles are actually SDMA byte read accesses (see 4.2
SDMA Channels for more details). All timings, signals, and arbitration characteristics of
SDMA accesses apply to the DRAM refresh controller accesses. For example, DRAM re-
fresh cycles activate the BCLR signal, just like the SDMA. Note that the function code bits
may be used to distinguish DRAM refresh cycles from SDMA cycles, if desired.
A bus error on a DRAM refresh controller access causes the BERR channel number at offset
BASE + $67C to be written with a $0001. This is also the value written if the SCC1 receive
SDMA channel experiences a bus error; thus, these two sources cannot be distinguished
upon a bus error. The DRAM refresh SDMA channel and SCC1 receive SDMA channel are
separate and independent in all other respects.
3.10.3 Refresh Request Calculations
A typical 1-Mbyte DRAM needs one refresh cycle every 15.625 s. The DRAM refresh con-
troller is configured to execute one refresh cycle per request; thus, the PB8 pin should see
a high-to-low transition every 15.625 s. This is once every 260 cycles for a 16.67-MHz
clock. Note that one refresh per request minimizes the speed loss on the SCC channels.
MOTOROLA
TOUT OR BRG
PB8
MC68302
Figure 3-13. DRAM Control Block Diagram
DATA
MC68302 USER’S MANUAL
CONTROL
ADDRESS
BUFFERS
ADDRESS
MUX
System Integration Block (SIB)
DRAM
BANK
PAL
CONTROL
3-67