Digi NS9215 - Manual (Page 207)

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M E M O R Y C O N T R O L L E R
Static memory controller
www.digiembedded.com 207
2
When the power-on reset ( reset_n ) goes inactive, the processor starts booting
from 0x00000000 in memory.
3
The software programs the optimum delay values in flash memory so the boot
code can run at full speed.
4
The code branches to chip select 1 so the code can continue executing from the
non-remapped memory location.
5
The appropriate values are programmed into the memory controller to
configure chip select 4, and the memory device is initialized.
6
The address mirroring is disabled by clearing the address mirror (M) field in the
Control register.
7
The ARM reset and interrupt vectors are copied from flash memory to SDRAM
that can then be accessed at address
0x00000000 .
8
More boot, initialization, or application code is executed.
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S t a t i c m e m o r y c o n t r o l l e r
This table shows configurations for the static memory controller with different
types of memory devices. See “StaticMemory Configuration 0–3 registers” on
page 251 for more information.
Device Write protect Page mode Buffer
ROM Enabled Disabled Disabled a
Page mode ROM Enabled Enabled Enabled a
Extended wait ROM Enabled Disabled Disabled a
SRAM Disabled (or enabled) b Disabled Disabled a
Page mode SRAM Disabled (or enabled) b Enabled Enabled a
Extended wait SRAM Disabled (or enabled)
b
Disabled Disabled
a
Flash Disabled or (enabled)
b
Disabled Disabled
c
Page mode flash Disabled or (enabled) b Enabled Enabled c
Extended wait flash Disabled or (enabled) b Disabled Disabled a
Memory mapped peripheral Disabled (or enabled) b Disabled Disabled
a Enabling the buffers means that any access causes the buffer to be used. Depending on the
application, this can provide performance improvements. Devices without async-page-mode
support generally work better with the buffer disabled. Again, depending on the application, this
can provide performance improvements.
b SRAM and Flash memory devices can be write-protected if required.
c Buffering must be disabled when performing Flash memory commands and during writes.