UPD78F1502AGK-GAK-AX Datasheet, PDF (727/1031 Pages) Renesas Technology Corp – 16-Bit Single-Chip Microcontrollers

78K0R/Lx3
CHAPTER 17 MULTIPLIER/DIVIDER
(2) Multiplication/division data register B (MDBL, MDBH)
The MDBH and MDBL registers set the values that are used for multiplication or division operation and store the
operation result. They store the operation result (product) in the multiplication mode and set the divisor data in the
division mode.
MDBH and MDBL can be set by a 16-bit manipulation instruction.
Reset signal generation clears these registers to 0000H.
Figure 17-3. Format of Multiplication/Division Data Register B (MDBH, MDBL)
Address: FFFF4H, FFFF5H, FFFF6H, FFFF7H After reset: 0000H, 0000H R/W
Symbol
FFFF7H
FFFF6H
MDBH MDBH MDBH MDBH MDBH MDBH MDBH MDBH MDBH MDBH MDBH MDBH MDBH MDBH MDBH MDBH MDBH
15 14 13 12 11 10 9
8
7
6
5
4
3
2
1
0
Symbol
FFFF5H
FFFF4H
MDBL
MDBL MDBL MDBL MDBL MDBL MDBL MDBL MDBL MDBL MDBL MDBL MDBLMDBHLMDBL MDBL MDBL
15 14 13 12 11 10 9
8
7
6
5
4
3
2
1
0
Cautions 1. Do not rewrite the MDBH and MDBL values during division operation processing (while the
multiplication/division control register (MDUC) is 81H). The operation result will be an
undefined value.
2. Do not set MDBH and MDBL to 0000H in the division mode. If they are set, the operation
result will be an undefined value.
The following table shows the functions of MDBH and MDBL during operation execution.
DIVMODE
0
1
Table 17-3. Functions of MDBH and MDBL During Operation Execution
Operation Mode
Multiplication mode
Division mode
Setting
−
MDBH: Divisor (higher 16 bits)
MDBL: Dividend (lower 16 bits)
Operation Result
MDBH: Multiplication result (product)
Higher 16 bits
MDBL: Multiplication result (product)
Lower 16 bits
−
Remark DIVMODE: Bit 7 of the multiplication/division control register (MDUC)
R01UH0004EJ0501 Rev.5.01
711
Jun 20, 2011