Datasheet

Section 2 CPU
Rev. 2.00 Sep. 23, 2005 Page 37 of 444
REJ09B0068-0200
2.8 Usage Notes
2.8.1 Notes on Data Access to Empty Areas
The address space of this LSI includes empty areas in addition to the ROM, RAM, and on-chip
I/O registers areas available to the user. When data is transferred from CPU to empty areas, the
transferred data will be lost. This action may also cause the CPU to malfunction. When data is
transferred from an empty area to CPU, the contents of the data cannot be guaranteed.
2.8.2 EEPMOV Instruction
EEPMOV is a block-transfer instruction and transfers the byte size of data indicated by R4L,
which starts from the address indicated by R5, to the address indicated by R6. Set R4L and R6 so
that the end address of the destination address (value of R6 + R4L) does not exceed H'FFFF (the
value of R6 must not change from H'FFFF to H'0000 during execution).
2.8.3 Bit-Manipulation Instruction
The BSET, BCLR, BNOT, BST, and BIST instructions read data from the specified address in
byte units, manipulate the data of the target bit, and write data to the same address again in byte
units. Special care is required when using these instructions in cases where two registers are
assigned to the same address, or when a bit is directly manipulated for a port or a register
containing a write-only bit, because this may rewrite data of a bit other than the bit to be
manipulated.
(1) Bit Manipulation for Two Registers Assigned to Same Address
Example 1: Bit manipulation for the timer load register and timer counter (Applicable for
timer B1 in the H8/36064 Group.)
Figure 2.13 shows an example of a timer in which two timer registers are assigned to the same
address. When a bit-manipulation instruction accesses the timer load register and timer counter of
a reloadable timer, since these two registers share the same address, the following operations takes
place.
1. Data is read in byte units.
2. The CPU sets or resets the bit to be manipulated with the bit-manipulation instruction.
3. The written data is written again in byte units to the timer load register.