Chapter 7 External Bus Controller
7-13
7.3.7 Access
Timing
7.3.7.1 SHWT
Option
The SHWT option is selected when the SHWT (Setup/Hold Wait Time) field of the Channel
Control Register is a value other than “0.” This option inserts Setup cycles and Hold cycles
between signals as follows.
Setup cycle: CE* from ADDR, OE* from CE*, BWE* from CE*, SWE* from CE*.
Hold cycle: ADDR from CE*, CE* from OE*, CE* from BWE*, CE* from SWE*
This option is used for I/O devices that are generally slow. All Setup cycles and Hold cycles
will be identical, so each cycle cannot be set individually.
The SHWT mode cannot be used by the Page mode. The SHWT mode can be used by all other
modes, but there is one restriction: the internal bus cannot use Burst access.
The hold cycles of DATA relative to SWE* and BWE* are fixed at one clock cycle, regardless
of the settings of the SHWT option. When the SHWT option is disabled, the setup cycles of SEW*
and BWE* relative to CE*, and the hold cycles of OE*, SEW* and BWE* relative to CE* are one
clock cycle.
Figure 7.3.5 SWHT Disable (Normal Mode, Single Read/Write Cycle)
SYSCLK
CE
*
/BE
*
ADDR [19:0]
OE
*
DATA [31:0]
ACK
*
/READY
(Output)
EBCCRn.PWT:WT=0
EBCCRn.SHWT=0
SWE
*
/BWE
*
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 ...
Page 491: ...Chapter 16 Removed 16 1 16 Removed ...
Page 492: ...Chapter 16 Removed 16 2 ...
Page 493: ...Chapter 17 Removed 17 1 17 Removed ...
Page 494: ...Chapter 17 Removed 17 2 ...
Page 495: ...Chapter 18 Removed 18 1 18 Removed ...
Page 496: ...Chapter 18 Removed 18 2 ...
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 ...