HD6433308 Datasheet, PDF (38/349 Pages) Hitachi Semiconductor – Hitachi Single-Chip MicroComputer

2.4 Mode and System Control Registers (MDCR and SYSCR)
Two of the control registers in the register field are the mode control register (MDCR) and system
control register (SYSCR). The mode control register controls the MCU mode: the operating mode
of the H8/330 chip. The system control register has bits that enable or disable the on-chip RAM
and dual-port RAM. Table 2-2 lists the attributes of these registers.
Table 2-2. Mode and System Control Registers
Name
Mode control register
System control register
Abbreviation
MDCR
SYSCR
Read/Write
R
R/W
Address
H’FFC5
H’FFC4
2.4.1 Mode Control Register (MDCR) – H’FFC5
Bit
7
6
5
4
3
2
1
0
—
—
—
—
—
— MDS1 MDS0
Initial value
1
1
1
0
0
1
*
*
Read/Write
—
—
—
—
—
—
R
R
* Initialized according to MD1 and MD0 inputs.
Bits 7 to 5 and 2—Reserved: These bits cannot be modified and are always read as “1.”
Bits 4 and 3—Reserved: These bits cannot be modified and are always read as “0.”
Bits 1 and 0—Mode Select 1 and 0 (MDS1 and MDS0): These bits indicate the values of the
mode pins (MD1 and MD0) latched on the rising edge of the RES signal. These bits can be read but
not written.
Coding example: To test whether the MCU is operating in mode 1:
MOV.B @H’FFC5, R0L
CMP.B #H’E5, R0L
The comparison is with H’E5 instead of H’01 because bits 7, 6, 5, and 2 are always read as “1.”
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