HD6475348R Datasheet, PDF (48/487 Pages) Hitachi Semiconductor – Single-Chip Microcomputer

2.4 Mode Control Register (MDCR)
Another control register in the register field in page 0 is the mode control register (MDCR). The
mode control register can be read by the CPU, but not written. Table 3-2 lists the attributes of this
register.
Table 2-2 Mode Control Register
Name
Mode control register
Abbreviation
MDCR
Read/Write
Read only
Address
H'FF12
The bit configuration of this register is shown below.
Bit
7
6
5
4
3
2
1
0
—
—
—
—
— MDS2 MDS1 MDS0
Initial value
1
1
0
0
0
*
*
*
Read/Write
—
—
—
—
—
R
R
R
* Initialized according to MD2 to MD0.
Bits 7 and 6—Reserved: These bits cannot be modified and are always read as 1.
Bits 5 to 3—Reserved: These bits cannot be modified and are always read as 0.
Bits 2 to 0—Mode Select 2 to 0 (MDS2 to MDS0): These bits indicate the values of the mode
pins (MD2 to MD0) latched on the rising edge of the signal. MDS2 corresponds to MD2, MDS1
to MD1, and MDS0 to MD0. These bits can be read but not written.
Coding Example: To test whether the MCU is operating in mode 1:
CMP:G.B #H'C1, @H'FF12
The comparison is with H'C1 instead of H'01 because bits 7 and 6 are always read as 1.
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