
External Memory Controller (EMC)
Symphony DSP56724/DSP56725 Multi-Core Audio Processors, Rev. 0
Freescale Semiconductor
21-71
7. Read the MxMR register (to ensure that the MxMR register has already been updated with the
desired configuration, such as RAM array address).
8. Perform a dummy read transaction (so that a read transaction can now be performed).
9. Read/check the MxMR[MAD] bit. If the MAD bit is incremented then the previous dummy read
transaction is completed and proceed to step 10, or remain at step 9 otherwise.
10. Read the MDR register.
21.4.4.3
UPM Signal Timing
RAM word fields specify the value of the various external signals at a granularity of up to four values for
each bus clock cycle. The signal timing generator causes external signals to behave according to the timing
specified in the current RAM word.
For CRR[CLKDIV] = 4 or 8, each bit in the RAM word relating to LCSx timing specifies the value of the
corresponding external signal at each quarter phase of the bus clock.
If CRR[CLKDIV] = 2, the external signal can change value only on each half phase of the bus clock. If
the RAM word in this case (LCRR[CLKDIV] = 2) specifies a quarter phase signal change, the signal
timing generator interprets this as a half cycle change.
The division of UPM bus cycles into phases is shown in
CRR[CLKDIV] = 2, the bus cycle comprises only two active phases (T1, T3), which correspond with the
first and second halves of the bus clock cycle, respectively.
However, if CRR[CLKDIV] = 4 or 8, four phases, T1–T4, define four quarters of the bus clock cycle.
Because T2 and T4 are inactive when CRR[CLKDIV] = 2, UPM ignores the signal timing programmed
for assertion in either of these phases in the case CRR[CLKDIV] = 2.
Figure 21-37. UPM Clock Scheme for CRR[CLKDIV] = 2
LCLK
T1
T2
T3
T4