PD17225_15 Datasheet, PDF (20/86 Pages) Renesas Technology Corp – 4-BIT SINGLE-CHIP MICROCONTROLLER FOR SMALL GENERAL-PURPOSE INFRARED REMOTE CONTROL TRANSMITTER

µPD17225, 17226, 17227, 17228
2.4.3 General register (GR)
A general register is a 16-word register on the data memory and used for arithmetic operations and transfer of data
to and from the data memory.
(1) Configuration of general register
Figure 2-6 shows the configuration of the general register.
A general register occupies 16 nibbles (16 × 4 bits) on a selected row address of the data memory.
The row address is selected by the general register pointer (RP) of the system register. The RP having four
significant bits in the µPD17227 and 17228 can point to any row address in the range of 0H to 7H of each
bank (BANK0 and BANK1).
In the µPD17225 and 17226, 3 bits are available in the RP. These bits can point to any row address in the
range of 0H to 7H of BANK0.
(2) Functions of the general register
The general register enables an arithmetic operation and data transfer between the data memory and a
selected general register by a single instruction. As a general register is a part of the data memory, you can
say that the general register enables arithmetic operation and data transfer between two locations of the data
memory. Similarly, the general register can be accessed by a data memory manipulation instruction as it is
a part of the data memory.
Figure 2-6. Configuration of General Registers
General register pointer
(RP)
RPH
RPL
BANK0
Column address
b 3 b 2 b 1 b 0 b3 b2 b1 b 0
0 1 2 3 4 5 6 7 8 9 A B C D EF
F F F 0 0 0 0 →0
iii
xxx ⁰⁰⁰¹
→1
e
d
e
d
e
d
0
0
1
0
A
s
→
2
t
o
t
o
t
o
0
0
0
1
1
0
1
0
s →3
i
g^→4
0 0 0 _{0 1 0 1} n→₅
e
0 1 1 0 _d→6
0 1 1 1 → 7 Port register
t
o
BANK1
1 0 0 0 _B→0
1 0 0 1 C→1
1 0 1 0 ^D→2
1 0 1 1 f →3
l
1 1 0 0 _a→4
1 1 0 1 ^g→5
General registers (16 nibbles)
System registers
← _Example
General registers
when
RP = 0000010B
Port
regis-
ter
RP
General register
settable range
Same system
registers exist
1 1 1 0 →6
1 1 1 1 →7
System registers
18
Data Sheet U12643EJ2V0DS00