AT89LP213 datasheet(11/90 Pages) ATMEL

11 / 90 page

3538A–MICRO–7/06

AT89LP213/214 [Preliminary]

Figure 8-3.

Two-cycle ALU Operation (Example: ADD A, #data)

8.1

Restrictions on Certain Instructions

The AT89LP213/214 is an economical and cost-effective member of Atmel's growing family of

microcontrollers. It contains 2K bytes of Flash program memory. It is fully compatible with the

MCS-51 architecture, and can be programmed using the MCS-51 instruction set. However,

there are a few considerations one must keep in mind when utilizing certain instructions to pro-

gram this device. All the instructions related to jumping or branching should be restricted such

that the destination address falls within the physical program memory space of the device, which

is 2K for the AT89LP213/214. This should be the responsibility of the software programmer. For

example, LJMP 7E0H would be a valid instruction, whereas LJMP 900H would not.

8.1.1

Branching Instructions

The LCALL, LJMP, ACALL, AJMP, SJMP, and JMP @A+DPTR unconditional branching instruc-

tions will execute correctly as long as the programmer keeps in mind that the destination

branching address must fall within the physical boundaries of the program memory size (loca-

tions 000H to 7FFH for the AT89LP213/214). Violating the physical space limits may cause

unknown program behavior. With the CJNE [...], DJNZ [...], JB, JNB, JC, JNC, JBC, JZ, and JNZ

conditional branching instructions, the same previous rule applies. Again, violating the memory

boundaries may cause erratic execution. For applications involving interrupts the normal inter-

rupt service routine address locations of the 8051 family architecture have been preserved.

8.1.2

MOVX-related Instructions, Data Memory

The AT89LP213/214 contains 128 bytes of internal data memory. RAM accesses to addresses

above 7FH will return invalid data. Furthermore, the stack depth is limited to 128 bytes, the

amount of available RAM. The Stack Pointer should not be allowed to point to locations above

7FH. External DATA memory access is not supported in this device, nor is external PROGRAM

memory execution. Therefore, no MOVX [...] instructions should be included in the program.

A typical 8051 assembler will still assemble instructions, even if they are written in violation of

the restrictions mentioned above. It is the responsibility of the user to know the physical features

and limitations of the device being used and to adjust the instructions used accordingly.

System Clock

Total Execution Time

Fetch Immediate Operand

ALU Operation Execute

Result Write Back

Fetch Next Instruction

AT89LP213 Datasheet(PDF) 11 Page - ATMEL Corporation