
S E R I A L C O N T R O L M O D U L E : S P I
SPI clock generation
436
Hardware Reference NS9215
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S P I c l o c k g e n e r a t i o n
The reference clock for the SPI module is the system PLL output. This clock is a
nominal 300 MHz.
In SPI master mode, the clock is divided down to produce the required data
rate.
In SPI slave mode, the divided down clock recovers the input SPI clock.
Clock generation
samples
SPI clock generation is specified using the Clock Generation register. These are
some examples of clock generation:
In SPI master
mode
In SPI master mode, the value programmed in the DIVISOR field must always be
rounded up to the next whole integer. For example, if the required data rate is 14
Mbps, the calculation is (300 / 14) or 21.43.
The value programmed in the DIVISOR field would be 0x016.
The actual data rate would be 13.64 Mbps.
The general equation is:
DIVISOR = round Up (PLL output / interface data rate)
In SPI slave mode
In SPI slave mode, the value programmed in the DIVISOR field should always be 0x006.
The SPI slave mode data rate is determined by the frequency of the input clock
provided by the external SPI master.
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S y s t e m b o o t - o v e r - S P I o p e r a t i o n
The NET+SPI ASIC boots from an external, non-volatile, serial memory device. The
device can be either a serial EEPROM or a serial Flash. In either case, the device
must support a four-wire, mode0-compatible SPI interface.
The boot-over-SPI hardware interfaces to devices requiring an 8-bit address, 16-bit
address, or 24-bit address. The address width is indicated by strapping pins
boot_mode[1:0]
.
Interface Type
Data rate
DIVISOR
Master
33 Mbps
0x009
Master
20 Mbps
0x00F
Master
5 Mbps
0x03C
Master
500 Kbps
0x258
Slave
all
0x006
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...
Страница 136: ...WOR KI N G W I TH T H E C P U Noncachable instruction fetches 136 Hardware Reference NS9215...
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...
Страница 515: ...PA CKA GING Processor Dimensions www digiembedded com 515...
Страница 516: ...PA CKA GING Processor Dimensions 516 Hardware Reference NS9215...