Datasheet

Section 3 MCU Operating Modes
Rev. 2.00 Sep. 28, 2009 Page 56 of 870
REJ09B0429-0200
3.2 Register Descriptions
The following registers are related to the operating mode. For details on the bus control register
(BCR), see section 6.3.1, Bus Control Register (BCR), and for details on bus control register 2
(BCR2), see section 6.3.2, Bus Control Register 2 (BCR2).
• Mode control register (MDCR)
• System control register (SYSCR)
• Serial timer control register (STCR)
3.2.1 Mode Control Register (MDCR)
MDCR is used to set an operating mode and to monitor the current operating mode.
Bit Bit Name
Initial
Value
R/W Description
7 EXPE 0 R/W Extended Mode Enable
Specifies extended mode.
0: Single-chip mode
1: Extended mode
6 to 3 — All 0 R Reserved
2
1
0
MDS2
MDS1
MDS0
—*
—*
—*
R
R
R
Mode Select 2, 1, and 0
These bits indicate the input levels at mode pins (MD2,
MD1, and MD0) (the current operating mode). Bits MDS2,
MDS1, and MDS0 correspond to MD2, MD1, and MD0,
respectively. MDS2 and MDS1 are read-only bits and they
cannot be written to. The mode pin (MD2, MD1, and MD0)
input levels are latched into these bits when MDCR is
read. These latches are canceled by a reset.
Note: * The initial values are determined by the settings of the MD2, MD1, and MD0 pins.