Renesas RL78 Series User Manual page 654

16-bit single-chip microcontrollers

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16.4.2 Multiplication (signed) operation

• Initial setting

<1> Set the multiplication/division control register (MDUC) to 08H.

<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.

Caution The data is in the two's complement format in multiplication mode (signed).

Steps <1> to <7> correspond to <1> to <7> in Figure 16-7.

Figure 16-7. Timing Diagram of Multiplication (Signed) Operation (–2 × 32767 = –65534)

Operation clock

R01UH0515EJ0120 Rev.1.20

Dec 16, 2016

CHAPTER 16 MULTIPLIER AND DIVIDER/MULTIPLY-ACCUMULATOR

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