參數(shù)資料
型號(hào): EC000UM
英文描述: EC000 Core User's Manual (SCM68000)
中文描述: EC000核心用戶手冊(cè)(SCM68000)
文件頁數(shù): 121/145頁
文件大?。?/td> 829K
代理商: EC000UM
Bus Operation
3-36
EC000 CORE PROCESSOR USER’S MANUAL
MOTOROLA
To achieve clock frequency independence at a system level, the bus can be operated in an
asynchronous manner. Asynchronous bus operation uses the bus handshake signals to
control the transfer of data. The handshake signals are ASB, UDSB, LDSB, DSB, DTACKB,
BERRB, HALTIB, and AVECB. ASB indicates the start of the bus cycle, and UDSB, LDSB,
and DSB signal valid data for a write cycle. After placing the requested data on the data bus
(read cycle) or latching the data (write cycle), the slave device (memory or peripheral)
asserts DTACKB to terminate the bus cycle. If no device responds or if the access is invalid,
external control logic asserts BERRB, or BERRB and HALTIB, to abort or retry the cycle.
Figure 3-29 shows the use of the bus handshake signals in a fully asynchronous read cycle.
Figure 3-30 shows a fully asynchronous write cycle.
In the asynchronous mode, the accessed device operates independently of the frequency
and phase of the system clock. For example, the MC68681 dual universal asynchronous
receiver/transmitter (DUART) does not require any clock-related information from the bus
master during a bus transfer. Asynchronous devices are designed to operate correctly with
processors at any clock frequency when relevant timing requirements are observed.
Figure 3-29. Fully Asynchronous Read Cycle
Figure 3-30. Fully Asynchronous Write Cycle
ASB
RWB
DTACKB
UDSB and/or LDSB
D15–D0
A31–A0
and DSB
A31–A0
ASB
RWB
UDSB and/or LDSB
D15–D0
DTACKB
and DSB
F
re
e
sc
a
le
S
e
m
ic
o
n
d
u
c
to
r,
I
Freescale Semiconductor, Inc.
For More Information On This Product,
Go to: www.freescale.com
n
c
..
.
相關(guān)PDF資料
PDF描述
EC103B Sensitive SCRs
EC103B1 Sensitive SCRs
EC103B2 Sensitive SCRs
EC103B3 Sensitive SCRs
EC103D175 Thyristor Product Catalog
相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
EC0010-000 制造商:TE Connectivity 功能描述:EC0010-000
EC001031 制造商:PHOENIX 制造商全稱:PHOENIX CONTACT 功能描述:Header, Nominal current: 12 A, Rated voltage (III/2): 320 V, Assembly: Soldering
EC001121 制造商:PHOENIX 制造商全稱:PHOENIX CONTACT 功能描述:Plug component, Nominal current: 12 A, Rated voltage (III/2): 320 V, Number of positions: 4, Pitch: 5mm, Connection method: Screw connection, Color: Black, Contact surface: Tin
EC001283 制造商:PHOENIX 制造商全稱:PHOENIX CONTACT 功能描述:Plug component, Nominal current: 12 A, Rated voltage (III/2): 320 V, Number of positions: 7, Pitch: 5.08 mm, Connection method: Solder/Slip-on connection, Color: green, Contact surface: Tin, Assembly: Direct mounting
EC0013-000 制造商:TE Connectivity 功能描述:EC0013-000