Symphony DSP56724/DSP56725 Multi-Core Audio Processors, Rev. 0
21-40
Freescale Semiconductor
External Memory Controller (EMC)
during a read, write, burst-read, or burst-write access. Refresh timers are also available to
periodically initiate user-defined refresh patterns.
Figure 21-2. Basic Operation of Memory Controllers in EMC
Each memory bank (chip select) can be assigned to any one of these three type of machines via the machine
select bits of the base register for that bank (BRx[MSEL]), as illustrated in
. If a bank match
occurs, the corresponding machine (GPCM, SDRAM or UPM) then takes ownership of the external
signals that control the access and maintains control until the transaction ends.
21.4.1
Basic Architecture
21.4.1.1
Address and Address Space Checking
The defined base addresses are written to the BRx registers, while the corresponding address masks are
written to the ORx registers. Each time an external memory access is requested, the internal transaction
address is compared with each bank. Addresses are decoded by comparing the 11 MSBs of the address,
masked by ORx[XAM] and ORx[AM], with the base address for each bank (BRx[XBA] and BRx[BA]).
If a match is found on a memory controller bank, the attributes defined in the BRx and ORx for that bank
are used to control the memory access. If a match is found in more than one bank, the lowest-numbered
bank handles the memory access (that is, bank 0 has priority over bank 1).
Address
Comparator
Bank Select
UPM A/B/C
GPCM
MSEL
Field
Signals
Timing
Generator
MUX
Internal Memory Access Request Select
26-bit System
External Signals
SDRAM Machine
Address
24-bit Physical
RAM Address (A)
Base
Register
Содержание Symphony DSP56724
Страница 22: ...Symphony DSP56724 DSP56725 Multi Core Audio Processors Rev 0 1 10 Freescale Semiconductor Introduction ...
Страница 52: ...Symphony DSP56724 DSP56725 Multi Core Audio Processors Rev 0 2 30 Freescale Semiconductor Signal Descriptions ...
Страница 112: ...Symphony DSP56724 DSP56725 Multi Core Audio Processors Rev 0 7 12 Freescale Semiconductor Clock Generation Module CGM ...
Страница 244: ...Symphony DSP56724 DSP56725 Multi Core Audio Processors Rev 0 14 6 Freescale Semiconductor Shared Bus Arbiter ...
Страница 246: ...Symphony DSP56724 DSP56725 Multi Core Audio Processors Rev 0 15 2 Freescale Semiconductor Shared Memory Shared Memory ...