
M E M O R Y C O N T R O L L E R
Static memory write control
216
Hardware Reference NS9215
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S t a t i c m e m o r y w r i t e c o n t r o l
Write enable
programming
delay
The delay between the assertion of the chip select and the write enable is
programmable from 1 to 16 cycles using the
WAITWEN
bits of the Static Memory
Write Enable Delay (StaticWaitWen[3:0]) registers. The delay reduces the power
consumption for memories. The write enable is asserted on the rising edge of
HCLK
after the assertion of the chip select for zero wait states. The write enable is
always deasserted a cycle before the chip select, at the end of the transfer.
datamask_n
(byte lane signal) has the same timing as
st_we_n
(write enable signal) for
writes to 8-bit devices that use the byte lane selects instead of the write enables.
SRAM
Write timing for SRAM starts with assertion of the appropriate memory bank chip
selects (
cs[n]_n
) and address signals (
addr[27:0]_n
). The write access time is determined
by the number of wait states programmed for the
WAITWR
field in the Static
Memory Write Delay register (see “Static Memory Write Delay 0–3 registers” on
page 257). The
WAITTURN
field in the bank control register (see “StaticMemory Turn
Round Delay 0–3 registers” on page 258) determines the number of bus turnaround
wait states added between external read and write transfers.
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S t a t i c m e m o r y W r i t e : T i m i n g a n d p a r a m e t e r s
This section shows static memory write timing diagrams and parameters.
External memory
write transfer
with zero wait
states
This diagram shows a single external memory write transfer with minimum zero
wait states (
WAITWR=0
). One wait state is added.
data
cs[n]
clk_out
addr
st_we_n
A
D(A)
Содержание NS9215
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Страница 44: ...P I N O U T 26 5 System clock 44 Hardware Reference NS9215 System clock drawing...
Страница 52: ...P I N O U T 26 5 Power and ground 52 Hardware Reference NS9215...
Страница 80: ...I O C O N T ROL M O D U L E Memory Bus Configuration register 80 Hardware Reference NS9215...
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Страница 202: ...S Y S T E M C O N T RO L M OD U L E RTC Module Control register 202 Hardware Reference NS9215...
Страница 260: ...M E MO R Y C O N T ROL L E R StaticMemory Turn Round Delay 0 3 registers 260 Hardware Reference NS9215...
Страница 354: ...E X T E R N A L D M A DMA Peripheral Chip Select register 354 Hardware Reference NS9215...
Страница 362: ...A E S D AT A E N C R Y P T I O N D E C R Y P T I O N M O D U L E CCM mode 362 Hardware Reference NS9215...
Страница 384: ...I O HU B M OD UL E Module Direct Mode TX Data Last FIFO 384 Hardware Reference NS9215 31 March 2008...
Страница 414: ...S E R I A L C ON T RO L M O D U L E U ART UART Modem Status register 414 Hardware Reference NS9215...
Страница 446: ...S E R I A L C ON T RO L M O D U L E S PI SPI timing characteristics 446 Hardware Reference NS9215...
Страница 472: ...R E A L TI M E C L O C K M O D U L E General Status register 472 Hardware Reference NS9215...
Страница 512: ...TI M I NG Clock timing 512 Hardware Reference NS9215...
Страница 514: ...PA CKA GING Processor Dimensions 514 Hardware Reference NS9215 P r o c e s s o r D i m e n s i o n s...
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