UPD78F1502AGK-GAK-AX Datasheet, PDF (870/1031 Pages) Renesas Technology Corp – 16-Bit Single-Chip Microcontrollers

78K0R/Lx3
CHAPTER 29 BCD CORRECTION CIRCUIT
CHAPTER 29 BCD CORRECTION CIRCUIT
29.1 BCD Correction Circuit Function
The BCD correction circuit is mounted onto all 78K0R/Lx3 microcontroller products.
The result of addition/subtraction of the BCD (binary-coded decimal) code and BCD code can be obtained as BCD
code with this circuit.
The decimal correction operation result is obtained by performing addition/subtraction having the A register as the
operand and then adding/ subtracting the BCDADJ register.
29.2 Registers Used by BCD Correction Circuit
The BCD correction circuit uses the following registers.
• BCD correction result register (BCDADJ)
(1) BCD correction result register (BCDADJ)
The BCDADJ register stores correction values for obtaining the add/subtract result as BCD code through
add/subtract instructions using the A register as the operand.
The value read from the BCDADJ register varies depending on the value of the A register when it is read and those
of the CY and AC flags.
BCDADJ is read by an 8-bit memory manipulation instruction.
Reset input sets this register to undefined.
Figure 29-1. Format of BCD Correction Result Register (BCDADJ)
Address: F00FEH After reset: undefined R
Symbol
7
6
5
4
3
2
1
0
BCDADJ
R01UH0004EJ0501 Rev.5.01
854
Jun 20, 2011