34
2.2.2
System Control Register (SYSCR)
Bit
7
6
5
4
3
2
1
0
—
—
MACS
—
FLSHE
—
EXPE
RAME
Initial value
1
1
0
0
0
0
—
*
1
Read/Write
R/W
R/W
R/W
R/W
R/W
—
R/W
R/W
Note:
*
Determined by pins MD2 to MD0.
Bits 7 and 6—Reserved: These are readable/writable bits, but the write value should always be 1.
Bit 5—MAC Saturation (MACS): Selects either saturating or non-saturating calculation for the
MAC instruction.
Bit 5
MACS
Description
0
Non-saturating calculation for MAC instruction
(Initial value)
1
Saturating calculation for MAC instruction
Bit 4—Reserved: This is a readable/writable bit, but the write value should always be 0.
Bit 3—Flash Memory Control Register Enable (FLSHE): Controls CPU access to the flash
memory control registers (FLMCR1, FLMCR2, EBR1, and EBR2). For details see section 18,
ROM, in the H8S/2678 Series Hardware Manual.
In the mask ROM and ROMless versions, 0 should be written to this bit.
Bit 3
FLSHE
Description
0
Flash memory control registers are not selected for area H'FFFFC8 to H'FFFFCB
(Initial value)
1
Flash memory control registers are selected for area H'FFFFC8 to H'FFFFCB
Bit 2—Reserved: This bit is always read as 0 and cannot be modified. The write value should
always be 0.
Bit 1—External Bus Mode Enable (EXPE): Sets external bus mode.
In modes 1, 2, 4, 5, 6, 10, 12, 13, and 14, this bit is fixed at 1 and cannot be modified. In modes 7,
11, and 15, this bit has an initial value of 0, and can be read and written.
Содержание H8S/2670
Страница 5: ......
Страница 9: ......
Страница 199: ...182 ...
Страница 361: ...344 ...
Страница 393: ...376 ...
Страница 647: ...630 ...