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SDC Functional Description
6-46
ADSP-BF537 Blackfin Processor Hardware Reference
4. Reprogram the SDRAM registers with values appropriate to the
new
SCLK
frequency, and assure that the
PSSE
bit is set.
5. Bring the SDRAM out of self-refresh mode by clearing the
SRFS
bit
of
EBIU_SDGCTL
.
Changing Power Management During Runtime
Deep Sleep Mode
During deep sleep mode, the core and system clock will halt. Therefore, a
careful software control is required to enter SDRAM in self-refresh before
the device enters deep sleep mode.
Hibernate State
In hibernate state, only the I/O voltage is applied, the core voltage is 0
(core reset). In order to save the SDRAM’s volatile data, the ADSP-BF537
supports low level of
SCKE
pin even during core reset. Setting the
SCKELOW
bit of
VR_CTL
keeps the
SCKE
signal low thus ensuring self-refresh mode.
Chapter 20, “Dynamic Power Management”
Shared SDRAM
Busmastership can be requested using
BR
and
BG
pins. To grant busmaster-
ship to external SDC, use the
CDDBG
bit of
EBIU_SDGCTL
. This occurs
asynchronously during self-refresh mode, because both auto-refresh time
bases are fully independent and will be synchronized during the
t
XSR
tim-
ing spec by each busmaster, leaving the self-refresh mode to get access to
shared SDRAM. The system requires additional logic for a common con-
trol of the SDRAM’s
CKE
pin. The following steps illustrate the
recommended procedure.
1. Boot stream of ADSP-BF537 processor must set the
CDDBG
bit of
EBIU_SDGCTL
to allow busmastership to a host.
2. SDRAM dummy access will perform the powerup sequence.
Содержание Blackfin ADSP-BF537
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Страница 90: ...Development Tools 1 32 ADSP BF537 Blackfin Processor Hardware Reference ...
Страница 138: ...Programming Examples 4 26 ADSP BF537 Blackfin Processor Hardware Reference ...
Страница 340: ...SDC Programming Examples 6 84 ADSP BF537 Blackfin Processor Hardware Reference ...
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Страница 720: ...Electrical Specifications 11 60 ADSP BF537 Blackfin Processor Hardware Reference ...
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Страница 1162: ...G 26 ADSP BF537 Blackfin Processor Hardware Reference ...
Страница 1218: ...Index I 56 ADSP BF537 Blackfin Processor Hardware Reference ...