Renesas rl78 User Manual

Page of 1004
 
RL78/G1A 
CHAPTER  14   MULTIPLIER  AND  DIVIDER/MULTIPLY-ACCUMULATOR 
14.4  Operations of Multiplier and Divider/Multiply-Accumulator 
 
14.4.1  Multiplication (unsigned) operation 
 
• Initial setting 
<1>  Set the multiplication/division control register (MDUC) to 00H. 
<2>  Set the multiplicand to multiplication/division data register A (L) (MDAL). 
<3>  Set the multiplier to multiplication/division data register A (H) (MDAH). 
 
(There is no preference in the order of executing steps <2> and <3>.  Multiplication operation is automatically 
started when the multiplier and multiplicand are set to the MDAH and MDAL registers, respectively.) 
•  During operation processing 
<4>  Wait for at least one clock.  The operation will end when one clock has been issued. 
• Operation end 
<5>  Read the product (lower 16 bits) from multiplication/division data register B (L) (MDBL). 
<6>  Read the product (higher 16 bits) from multiplication/division data register B (H) (MDBH). 
(There is no preference in the order of executing steps <5> and <6>.) 
• Next operation 
<7>  Start with the initial settings of each step to change the operation mode.  When the same operation mode is 
used sequentially, settings <1> and <2> can be omitted. 
 
Remark  Steps <1> to <7> correspond to <1> to <7> in Figure 14-6. 
 
Figure 14-6.  Timing Diagram of Multiplication (Unsigned) Operation (2 
× 3 = 6) 
 
MDAL
0002H
0003H
0000H
0006H
FFFFH
FFFFH
FFFEH
0001H
0002H
FFFDH
<2>
<1>
<3>
<5>, <6>
<4>
00H
MDAH
MDBH
MDBL
MDUC
MDSM
L
<7>
0000H
0000H
0000H
0000H
Operation clock
 
R01UH0305EJ0200  Rev.2.00 
 
 
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Jul 04, 2013