S3C72P9 datasheet(21/225 Pages) SAMSUNG

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S3C72P9/P72P9 (Preliminary Spec)

ADDRESS SPACES

2-9

Memory Banks 0, 1, 2, 3, 4 and 15

Bank 0

(000H–0FFH)

The lowest 32 nibbles of bank 0 (000H–01FH) are used as working registers;

the next 224 nibbles (020H–0FFH) can be used both as stack area and as

general-purpose data memory. Use the stack area for implementing subroutine

calls and returns, and for interrupt processing.

Bank 1

(100H–1FFH)

Bank 1 is used for general-purpose.

Bank 2

(200H–2FFH)

The 224 nibbles of bank 2 are for display registers or general-purpose use;

locations 2xE and 2xF (x = 0–F) are for general-purpose use in bank 2.

Detailed map on bank 2 is shown in Section 12 LCD Controller/Driver.

Bank 3

(300H–3FFH)

Bank 3 is used for general-purpose.

Bank 4

(400H–4FFH)

Bank 4 is used for general-purpose.

Bank 15

(F80H–FFFH)

The microcontroller uses bank 15 for memory-mapped peripheral I/O. Fixed

RAM locations for each peripheral hardware address are mapped into this area.

Data Memory Addressing Modes

The enable memory bank (EMB) flag controls the addressing mode for data memory banks 0, 1, 2, 3, 4 or 15.

When the EMB flag is logic zero, the addressable area is restricted to specific locations, depending on whether

direct or indirect addressing is used. With direct addressing, you can access locations 000H–07FH of bank 0 and

bank 15. With indirect addressing, only bank 0 (000H–0FFH) can be accessed. When the EMB flag is set to logic

one, all four data memory banks can be accessed according to the current SMB value.

For 8-bit addressing, two 4-bit registers are addressed as a register pair. Also, when using 8-bit instructions to

address RAM locations, remember to use the even-numbered register address as the instruction operand.

Working Registers

The RAM working register area in data memory bank 0 is further divided into four register banks (bank 0, 1, 2,

and 3). Each register bank has eight 4-bit registers and paired 4-bit registers are 8-bit addressable.

bit can also be used as a 1-bit accumulator. Register pairs WX, WL, and HL are used as address pointers for

indirect addressing. To limit the possibility of data corruption due to incorrect register addressing, it is advisable

to use register bank 0 for the main program and banks 1, 2, and 3 for interrupt service routines.

LCD Data Register Area

Bit values for LCD segment data are stored in data memory bank 2. Register locations in this area that are not

used to store LCD data can be assigned to general-purpose use.

S3C72P9 Datasheet(PDF) 21 Page - Samsung semiconductor

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