参数资料
型号: MCW68332A
厂商: MOTOROLA INC
元件分类: 微控制器/微处理器
英文描述: 32-BIT, MICROCONTROLLER, UUC
封装: WAFER
文件页数: 33/111页
文件大小: 650K
代理商: MCW68332A
MOTOROLA
MC68332
28
MC68332TS/D
3.4.8 Data Transfer Mechanism
The MCU architecture supports byte, word, and long-word operands, allowing access to 8- and 16-bit
data ports through the use of asynchronous cycles controlled by the data transfer and size acknowledge
inputs (DSACK1 and DSACK0).
3.4.9 Dynamic Bus Sizing
The MCU dynamically interprets the port size of the addressed device during each bus cycle, allowing
operand transfers to or from 8- and 16-bit ports. During an operand transfer cycle, the slave device sig-
nals its port size and indicates completion of the bus cycle to the MCU through the use of the DSACK0
and DSACK1 inputs, as shown in the following table.
For example, if the MCU is executing an instruction that reads a long-word operand from a 16-bit port,
the MCU latches the 16 bits of valid data and then runs another bus cycle to obtain the other 16 bits.
The operation for an 8-bit port is similar, but requires four read cycles. The addressed device uses the
DSACK0 and DSACK1 signals to indicate the port width. For instance, a 16-bit device always returns
DSACK0 = 1 and DSACK1 = 0 for a 16-bit port, regardless of whether the bus cycle is a byte or word
operation.
Dynamic bus sizing requires that the portion of the data bus used for a transfer to or from a particular
port size be fixed. A 16-bit port must reside on data bus bits [15:0] and an 8-bit port must reside on data
bus bits [15:8]. This minimizes the number of bus cycles needed to transfer data and ensures that the
MCU transfers valid data.
The MCU always attempts to transfer the maximum amount of data on all bus cycles. For a word oper-
ation, it is assumed that the port is 16 bits wide when the bus cycle begins. Operand bytes are desig-
nated as shown in the following figure. OP0 is the most significant byte of a long-word operand, and
OP3 is the least significant byte. The two bytes of a word-length operand are OP0 (most significant) and
OP1. The single byte of a byte-length operand is OP0.
Figure 8 Operand Byte Order
3.4.10 Operand Alignment
The data multiplexer establishes the necessary connections for different combinations of address and
data sizes. The multiplexer takes the two bytes of the 16-bit bus and routes them to their required po-
sitions. Positioning of bytes is determined by the size and address outputs. SIZ1 and SIZ0 indicate the
remaining number of bytes to be transferred during the current bus cycle. The number of bytes trans-
ferred is equal to or less than the size indicated by SIZ1 and SIZ0, depending on port width.
Table 10 Effect of DSACK Signals
DSACK1
DSACK0
Result
1
Insert Wait States in Current Bus Cycle
1
0
Complete Cycle —Data Bus Port Size is 8 Bits
0
1
Complete Cycle —Data Bus Port Size is 16 Bits
0
Reserved
Operand
Byte Order
31
24
23
16
15
8
7
0
Long Word
OP0
OP1
OP2
OP3
Three Byte
OP0
OP1
OP2
Word
OP0
OP1
Byte
OP0
相关PDF资料
PDF描述
MC68EN360CEM25L 4 CHANNEL(S), 10M bps, LOCAL AREA NETWORK CONTROLLER, PQFP240
M30626FJPGP 16-BIT, FLASH, 24 MHz, MICROCONTROLLER, PQFP100
M30302MC-XXXGP 16-BIT, MROM, 16 MHz, MICROCONTROLLER, PQFP100
M37542F8TGP 8-BIT, FLASH, 8 MHz, MICROCONTROLLER, PQFP32
M37542M4-XXXFP 8-BIT, MROM, 8 MHz, MICROCONTROLLER, PDSO36
相关代理商/技术参数
参数描述
MCW-70A 制造商:SPC Multicomp 功能描述:WATERPROOF COVER BLACK TOGGL 制造商:SPC Multicomp 功能描述:WATERPROOF COVER, BLACK, TOGGLE SWITCH; For Use With:20mm Lever Height Toggle Switches; Actuator / Cap Color:Black
MCW-70B 制造商:SPC Multicomp 功能描述:WATERPROOF COVER BLACK TOGGL 制造商:SPC Multicomp 功能描述:WATERPROOF COVER, BLACK, TOGGLE SWITCH; For Use With:20mm Lever Height Toggle Switches; Actuator / Cap Color:Black
MCW74HC4851ATR DIE 制造商:ON Semiconductor 功能描述:
MCWF06R1000BTL 制造商:SPC Multicomp 功能描述:RESISTOR 0603 100R 0.1% 0.
MCWF06R1001BTL 制造商:SPC Multicomp 功能描述:RESISTOR 0603 1K 0.1% 0.1W