
External Memory Controller (EMC)
Symphony DSP56724/DSP56725 Multi-Core Audio Processors, Rev. 0
Freescale Semiconductor
21-49
Figure 21-6. GPCM Basic Write Timing
(XACS = 0, ACS = 00, CSNT = 1, SCY = 1, TRLX = 0, CLKDIV = 4, 8)
shows, the timing for LCSx is the same as for the latched address. The strobes for the
transaction are supplied by LOE or LWE, depending on the transaction direction—read or write (the write
case shown in
). ORx[CSNT] controls the timing for the appropriate strobe negation in write
cycles. When this attribute is asserted, the strobe is negated one quarter of a clock before the normal case
provided that CRR[CLDIV] = 4 or 8. For example, when ACS = 00 and CSNT = 1, LWE is negated one
quarter of a clock earlier, as shown in
. If CRR[CLDIV] = 2, LWE is negated either coincident
with LCSx or one cycle earlier.
21.4.2.2.3
Relaxed Timing
ORx[TRLX] is provided for memory systems that require more relaxed timing between signals. Setting
TRLX = 1 has the following effect on timing:
•
An additional bus cycle is added between the address and control signals (but only if ACS is not
equal to 00).
•
The number of wait states specified by SCY is doubled, providing up to 30 wait states.
•
The extended hold time on read accesses (EHTR) is extended further.
•
LCSx signals are negated one cycle earlier during writes (but only if ACS is not equal to 00).
•
LWE signals are negated one cycle earlier during writes.
LCLK
LAD
LALE
LCSx
LWE
A
TA
LOE
CSNT = 1
SCY = 1
Address
Write Data
Latched Address