RX610 Group
11. Buses
R01UH0032EJ0120 Rev.1.20
Page 297 of 1006
Feb 20, 2013
11.5.5
Notes on Usage
11.5.5.1
Limitations at the Time of Normal and Page Access
Limitations that apply to various bits of CSi wait control register 1 (CSiWCNT1) and CSi wait control register 2
(CSiWCNT2) at the times of normal and page access are listed in table 11.9.
If the setting of the page-read access enable bit in the CSi mode register or the page-write access enable bit in the CSi
mode register selects permission (CSiMOD.PRENB = 1 or CSiMOD.PWENB = 1), the limitations on normal access
must be satisfied in the first round of access for page access or in access that does not fall within the scope of page access
and thus leads to normal access operations. For details on the situations that are not within the scope of page access, see
section 11.5.1, Timing of External Bus Access.
Table 11.9 Limitations at the Time of Normal and Page Access
Limitations at the Time of Normal Access
Limitations at the Time of Page Access
Reading
Writing
Reading
Writing
CSON[2:0]
≤
CSRWAIT
RDON[2:0]
≤
CSRWAIT
CSON[2:0]
≤
RDON
CSON[2:0]
≤
CSWWAIT
WRON[2:0]
≤
CSWWAIT
WDON[2:0]
≤
CSWWAIT
WDOFF[2:0]
≤
CSWOFF
WDON[2:0]
≤
WRON
CSON[2:0]
≤
WRON
CSON[2:0]
≤
CSPRWAIT
RDON[2:0]
≤
CSPRWAIT
CSON[2:0]
≤
RDON
CSON[2:0]
≤
CSPWWAIT
WRON[2:0]
≤
CSPWWAIT
WDON[2:0]
≤
CSPWWAIT
WDOFF[2:0]
≤
CSWOFF
WDON[2:0]
≤
WRON
CSON[2:0]
≤
WRON
11.5.5.2
Prohibition of Access that Spans Areas of Address Space
Single access operations that span areas of the address space are prohibited, and operation in the case of attempts at such
access is not guaranteed. In cases where access to a single word or longword would produce access that crosses a
boundary between areas, split the instruction so that separate instructions are used for access to each of the areas.
11.5.5.3
Restrictions in Relation to RMPA and String-Manipulation Instructions
•
Although the external address space has a per-area ending-switching facility (only for data), the allocation of data to
be handled by RMPA or string-manipulation instructions to an area where the endian differs from that of the chip is
prohibited, and operation is not guaranteed if this restriction is not observed. If data to be handled by RMPA or
string-manipulation instructions are allocated to the external address space, they must be allocated to areas where
the endian setting is the same as that for the chip.
•
The allocation of data to be handled by RMPA or string-manipulation instructions to I/O registers is prohibited, and
operation is not guaranteed if this restriction is not observed.
11.5.5.4
Point for Caution Regarding Register Settings
•
Note on setting that affects the write data hold time (tWDH)
To secure the write data hold time, ensure that the setting of the CSiWCNT2.WDOFF[2:0] bits (write data output
extension cycle select bits) is at least 1. Take care to ensure that this condition is met, since not meeting the
condition may make securing the write data hold time impossible.