HD404629R Datasheet, PDF (18/157 Pages) Renesas Technology Corp – AS Microcomputer Incorporating a DTMF Generator Circuit

HD404629R Series
LCD Data Area ($050–$083): Used for storing 52-digit LCD data which is automatically output to LCD
segments as display data. Data 1 lights the corresponding LCD segment; data 0 extinguishes it. Refer to
the LCD description for details.
Data Area ($090–$3BF): 464 digits from $090 to $25F have three banks, which can be selected by setting
the bank register (V: $03F). Before accessing this area, set the bank register to the required value (figure
7). The area from $260 to $3BF is accessed without setting the bank register.
Bank register (V: $03F)
Bit
3
2
1
0
Initial value
—
—
0
0
Read/Write
—
—
R/W R/W
Bit name
Not used Not used V1
V0
V1
V0
Bank area selection
0
0
Bank 0 is selected
1
Bank 1 is selected
1
0
Bank 2 is selected
1
Not Used
Note: After reset, the value in the bank register is 0, and therefore bank 0 is
selected. If V1 = 1 and V0 = 1, no bank is selected, and the operation is not
guaranteed.
Figure 7 Bank Register (V)
Stack Area ($3C0–$3FF): Used for saving the contents of the program counter (PC), status flag (ST), and
carry flag (CA) at subroutine call (CAL or CALL instruction) and for interrupts. This area can be used as a
16-level nesting subroutine stack in which one level requires four digits. The data to be saved and the save
conditions are shown in figure 6.
The program counter is restored by either the RTN or RTNI instruction, but the status and carry flags can
only be restored by the RTNI instruction. Any unused space in this area is used for data storage.
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