AN1386 STMicroelectronics, AN1386 Datasheet - Page 10

• Manufacturer Part Number: AN1386
• Description: USING THE DSM2180F3 WITH THE ANALOG DEVICES ADSP-2185
• Manufacturer: STMicroelectronics

AN1386 - APPLICATION NOTE
Figure 6 shows a typical memory map with the following attributes:
Define the Memory Map in PSDsoft Express
The template’s memory map is setup according to Figure 6. First, note how the Page Register is setup,
shown in Figure 7.
Figure 7. DSM2180F3 Page Register Setup
The memory map is organized to work within the restrictions of the ADSP-2185 Boot Loader and to utilize
the entire Flash memory and show the paging features of the DSM2180F3.
The three paging bits will provide 2
shown in Figure 8.
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I/O Address Space. The 256 byte locations for DSM control registers (csiop) reside in DSP I/O address
space, selected by the DSP IOMS signal. Since DSP I/O accesses are 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 128 KBytes 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 accessed in 128 KB continuous byte address locations through the
BDMA channel and is selected whenever the DSP BMS signal is active. 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).
Data Overlay Memory Address Space. All 128 KBytes of Flash memory also reside in DSP External
Data-overlay Memory Space, selected by DMS, allowing more efficient byte writes to Flash memory.
The DSP uses its external data overlay window of 8 KB locations to access external memory as data.
The DSP doubles the size of this window to 16 KB locations by manipulating its A13 address line using
its DMOVLAY register (See the ADSP-2185 data sheet for details). Since all 128 KBytes of Flash
memory must be accessed through a window of only 16 KB locations, the DSP uses the Page Register
inside the DSM device to page through 8 pages of 16 KBytes, as shown in Figure 6. Since DSP Data
accesses are by 16 bits, not 8 bits, the upper byte of a 16-bit DSP Data access must be ignored.
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= 8 pages. Click Next to see the Chip Selection Equations screen,