Chapter 7 External Bus Controller
7-16
7.3.7.4 ACK
*
Input Timing (External ACK Mode)
The ACK* signal becomes an input signal when in the external ACK mode.
During a Read cycle, data is latched two clock cycles after assertion of the ACK* signal is
acknowledged (Figure 7.3.9 ACK* Input Timing (Single Read Cycle)). During a Write cycle,
assertion of the ACK* signal is acknowledged, SWE*/BWE* is deasserted three clock cycles
later, then data is held for one clock cycle after that (Figure 7.3.10 ACK* Input Timing (Single
Write Cycle).
The ACK* input signal is internally synchronized. Due to internal State Machine restrictions,
ACK* cannot be acknowledged consecutively on consecutive clock cycles. External devices can
assert ACK* across multiple clock cycles under the following conditions.
•
During Single access, the ACK* signal can be asserted before the end of the cycle during
which CE* is dasserted.
•
During Burst access, it is possible to assert the ACK* signal for up to three clock cycles
during Reads and for up to five clock cycles during Writes. If the ACK* signal is asserted for
a period longer than this, it will be acknowledged as the next valid ACK* signal.
Figure 7.3.9 ACK
*
Input Timing (Single Read Cycle)
Figure 7.3.10 ACK
*
Input Timing (Single Write Cycle)
SYSCLK
CE
*
ADDR [19
:
0]
OE
*
DATA [31
:
0]
ACK
*
/READY (Input)
Latch Data
Acknowledge ACK
*
2 clocks
EBCCRn.SHWT=0
SYSCLK
CE
*
ADDR [19:0]
SWE
*/
BWE
*
DATA [31:0]
ACK
*
/READY (Input)
3 clocks
4 clocks
Acknowledge ACK
*
EBCCRn.SHWT=0
Summary of Contents for TX49 TMPR4937
Page 1: ...64 Bit TX System RISC TX49 Family TMPR4937 Rev 2 0 ...
Page 4: ......
Page 13: ...Table of Contents ix TMPR4937 Revision History 1 ...
Page 14: ...Table of Contents x ...
Page 15: ...Handling Precautions ...
Page 16: ......
Page 18: ...1 Using Toshiba Semiconductors Safely 1 2 ...
Page 40: ...3 General Safety Precautions and Usage Considerations 3 18 ...
Page 42: ...4 Precautions and Usage Considerations 4 2 ...
Page 43: ...TMPR4937 2005 3 Rev 2 0 ...
Page 44: ......
Page 52: ...Chapter 1 Overview and Features 1 6 ...
Page 156: ...Chapter 7 External Bus Controller 7 56 ...
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Page 492: ...Chapter 16 Removed 16 2 ...
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Page 497: ...Chapter 19 Removed 19 1 19 Removed ...
Page 498: ...Chapter 19 Removed 19 2 ...
Page 506: ...Chapter 20 Extended EJTAG Interface 20 8 ...
Page 530: ...Chapter 22 Pinout and Package Information 22 10 ...
Page 542: ...Chapter 24 Parts Number when Ordering 24 2 ...