Symphony DSP56724/DSP56725 Multi-Core Audio Processors, Rev. 0
21-4
Freescale Semiconductor
External Memory Controller (EMC)
21.2.1
Detailed Signal Descriptions
Table 21-2. Detailed Signal Descriptions
Signal
I/O
Description
LALE
O External address latch enable. The EMC provides control for an external address latch, which allows
address and data to be multiplexed on the device pins.
State
Meaning
Asserted—LALE is asserted for at least 1/2 bus clock cycle for each memory-controller
transaction. If ORx[EAD] = 1, LALE is asserted for (N+1/2) bus clock cycles, where N is the
number of bus clock cycles defined by the EADC field in the CRR. Note that no other control
signals are asserted during the assertion of LALE.
Negated—LALE is negated at the negative edge of bus clock during address phase. LALE is
negated 1/2 bus clock cycle earlier than the next positive edge of bus clock, to obtain hold time
for external latch devices.
Timing
N/A
LCS[7:0]
O Chip selects. Eight mutually-exclusive chip selects are provided.
State
Meaning
Asserted/Negated—Used to enable specific memory devices or peripherals connected to the
EMC. LCS[7:0] are provided on a per-bank basis. For example, LCS0 is the chip select for
memory bank 0, which has the memory type and attributes defined by BR0 and OR0.
Timing
N/A
LWE/
LSDDQM/
O GPCM write enable/SDRAM data mask
State
Meaning
Asserted/Negated—For GPCM operation, LWE is asserted for writing.
For SDRAM operation, LSDDQM functions as the DQM or data mask signals provided by
JEDEC-compliant SDRAM devices. LSDDQM is driven high when the EMC wishes to mask a
write or disable read data output from the SDRAM.
Timing
N/A
LSDA10/
LGPL0
O SDRAM A10/General purpose line 0
State
Meaning
Asserted/Negated—For SDRAM accesses, this signal represents address bit 10. When the row
address is driven, this signal drives the value of address bit 10. When the column address is
driven, this signal forms part of the SDRAM command.
This signal is one of six general purpose signals when in UPM mode and drives a value
programmed in the UPM array
Timing
N/A
Содержание Symphony DSP56724
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