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HD6473258P10V Datasheet, PDF (34/301 Pages) Renesas Technology Corp – Hitachi Single-Chip Microcomputer | |||
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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 H8/325 Series chip. The system control register has a bit that enables or disables the on-chip
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
HâFFC5
HâFFC4
2.4.1 Mode Control Register (MDCR)âHâFFC5
Bit
7
6
5
4
3
2
1
0
â
â
â
â
â
â MDS1 MDS0
Initial value
1
1
1
0
0
1
*
*
Read/Write
R
R
R
R
R
R
R
R
* Initialized according to MD1 and MD0 inputs.
Bits 7 to 5 and 2âReserved: These bits cannot be modified and are always read as 1.
Bits 4 and 3âReserved: These bits cannot be modified and are always read as 0.
Bits 1 and 0âMode 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 @HâFFC5, R0L
CMP.B #HâE5, R0L
The comparison is with HâE5 instead of Hâ01 because bits 7, 6, 5, and 2 are always read as 1.
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