Mitsubishi DS907x SIP, DS5000TK Instruction SET, Addressing Modes, ADD A, R4, Setb 00H, Push P0

USER'S GUIDE

INSTRUCTION SET

Introduction

The Secure Microcontroller executes an instruction set which is object code compatible with the industry stan- dard 8051 microcontroller. As a result, software tools written for the 8051 are compatible with the Secure Microcontroller, including cross±assemblers, compil- ers, and debugging tools.

There are a total of 42 instruction types recognized by the Secure Microcontroller. When the instruction uses both source and destination operands, they are speci- fied in the order of ªdestination, sourceº.

Addressing Modes

There are eight addressing modes. Five of these are used to address operands. The other three are used in instructions which transfer execution of the program to another address (e.g., Branch, Jump, Call).

The modes which address source operands, include Register Addressing, Direct Addressing, Register±Indi- rect Addressing, Immediate Addressing and Register- Indirect with Displacement. The first three of these can also be used to address a destination operand. Most instructions use operands that are located in the Internal Data Registers.

The addressing modes used for the Control Transfer instructions include Relative Addressing, Page Addres- sing, and Extended Addressing.

The operation of these addressing modes is summa- rized below, followed by an example.

Register Addressing

Register Addressing is used on operands contained in one of the eight registers (R7±R0) of the currently se- lected Working Register Bank. A register bank is se- lected via a 2±bit field in the PSW Special Function reg- ister. All of the Working registers may also be accessed through either Direct Addressing or Register-Indirect Addressing as well. This is due to the fact that the Work- ing registers are mapped into the lower 32 bytes of Inter- nal Data RAM as discussed above.

ADD A, R4	; Add Accumulator to Working
	; register R4

Direct Addressing

Direct Addressing is the only mode available for use on operands within the Special Function registers. Ad- dressing of bytes may also be used to access the 128 Internal Data registers.

MOV 072H, 074H ; Load direct register (addr. 072H) ; with direct register (074H)

Direct addressing of bits is available on 128 bits located in the Internal Data registers in byte addresses of 20H ± 2FH inclusive. Direct bit addressing is also available in Special Function registers located at addresses on 8±byte boundaries starting at 80H (i.e., 80H, 88H, 90H, 98H, ...0F0H, 0F8H).

SETB 00H	; Set addressable bit 00H (D0 in
	; Internal Data Reg. 20H)

Register Indirect Addressing

Some instructions use Register±Indirect Addressing for accessing operands in other Internal Data registers. This is done by using the contents of Working register R1 or R0 as a pointer to other Internal Data registers.

ANL A, @R0 ; Logical AND of Accumulator with

;Internal Data register; pointed to

;by contents of R0

In addition, this addressing is used via the Stack Pointer register (SP) for manipulation of the stack. The stack area is contained in the Internal Data Register area. The PUSH and POP instructions are the only ones which use SP for this addressing mode.

PUSH P0	; Save the contents of the Port 0
	; SFR latch on the stack

The R0, R1, and the DPTR registers are used with Reg- ister±Indirect Addressing for accessing Data Memory. R1 or R0 in the selected Working Register bank may be used for accessing location within a 256±byte block pointed to by the current contents of the P2 SFR latch (address high byte).

MOVX A, @R1 ; Load the Accumulator with the

;contents of Data Memory

;addressed by the 8±bit contents

;of R1

050396 45/173

46