dsm2180f3 STMicroelectronics, dsm2180f3 Datasheet - Page 13

• Manufacturer Part Number: dsm2180f3
• Description: Dsm Digital Signal Processor System Memory For Analog Devices Adsp-218x Family 5v Supply
• Manufacturer: STMicroelectronics

MEMORY MAP
Figure 7 shows a typical system memory map.
The nomenclature fs0..fs7 are individual 16K Byte
Flash memory segment designators. csiop desig-
nates the DSM control register block. The DSP
runs in Full Memory Mode. Memory contents of
the DSM device may lie in one or more of three dif-
ferent DSP address spaces; I/O space, Byte DMA
space, and/or External Data Overlay Memory
space. Since the DSM device is a byte-wide mem-
ory, it typically is not used in DSP Program Mem-
ory space (
The designer may easily specify memory mapping
in a point-and-click software environment using
PSDsoft Express
implemented with the DPLD and the Page Regis-
ter, many possibilities exist. Figure 7 shows a typ-
ical memory map with the following attributes:
I/O Address Space. The 256 byte locations for
DSM control registers ( csiop ) reside in DSP I/O
address space, selected by the DSP
Since DSP I/O accesses are by 16 bits, not 8 bits,
the upper byte of a 16-bit DSP I/O access must be
ignored.
Byte DMA Address Space. The DSP may boot-
load or fetch overlay bytes from 128K Bytes of
Flash memory using the DSP BDMA channel. The
DSP may also write to Flash memory using the
Byte DMA channel. DSM Flash memory is access-
ed in 128K continuous byte address locations
PMS
active).
TM
. Since the memory mapping is
IOMS
signal.
through the BDMA channel and is selected when-
ever the DSP
Flash memory in the DSM device must be un-
locked and written by the DSP one byte at a time,
checking status after each write (typical Flash
memory programming algorithm). A DMA channel
is not optimum for this scenario since the channel
must be initialized on each byte access. That is
why the 128K Bytes of Flash memory also lie in
DSP Data Overlay Memory space as described
next.
Data Overlay Memory Address Space. All
128K Bytes of Flash memory also reside in DSP
External Data Overlay Memory space, selected by
DMS
memory. The DSP uses its external data overlay
window of 8K locations to access external memory
as data. The DSP doubles the size of this window
to 16K locations by manipulating its A13 address
line using its DMOVLAY register (See ADSP-218X
data sheets for details). Since all 128K Bytes of
Flash memory must be accessed through a win-
dow of only 16K locations, the DSP uses the Page
Register inside the DSM device to page through 8
pages of 16K Bytes as shown in Figure 7. Since
DSP Data accesses are by 16 bits, not 8 bits, the
upper byte of a 16-bit DSP Data access must be
ignored.
, allowing more efficient byte writes to Flash
BMS
signal is active.
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