Datasheet

V850ES/JG3-H, V850ES/JH3-H CHAPTER 5 BUS CONTROL FUNCTION
R01UH0042EJ0500 Rev.5.00 Page 193 of 1513
Aug 12, 2011
5.6 Idle State Insertion Function
To facilitate interfacing with low-speed memories, one idle state (TI) can be inserted after the T3 state in the bus cycle
that is executed for each space selected by the chip select. By inserting an idle state, the data output float delay time of
the memory can be secured during read access (an idle state cannot be inserted during write access).
Whether the idle state is to be inserted can be programmed by using the BCC register.
An idle state is inserted for all the areas immediately after system reset.
(1) Bus cycle control register (BCC)
The BCC register can be read or written in 16-bit units.
Reset sets this register to AAAAH.
Cautions 1. The internal ROM, internal RAM, and on-chip peripheral I/O areas are not subject to idle state
insertion.
2. Write to the BCC register after reset, and then do not change the set values. Also, do not
access an external memory area until the initial settings of the BCC register are complete.
After reset: AAAAH R/W Address: FFFFF48AH
1
BC31
BCn1
0
1
Not inserted
Inserted
BCC 0
0
1
BC21
0
0
1
BC11
Note
0
0
1
BC01
0
0
8
910
11
1213
Specifies insertion of idle state (n = 0 to 3)
1415
1234567 0
CS3 CS2 CS0
Note It is recommended to clear the BC11 bit to 0.
Caution Be sure to set bits 15, 13, 11, and 9 to “1”, and clear bits 14, 12, 10, 8, 6, 4, 2, and 0 to “0”.