What is DPTR in 8051?
The Data Pointer (DPTR) is the 8051’s only user-accessible 16-bit (2-byte) register. It is used by the 8051 to access external memory using the address indicated by DPTR. DPTR is the only 16-bit register available and is often used to store 2-byte values.
What is 8051 assembly language?
Assembly Language is a pseudo-English representation of the Machine Language. The 8051 Microcontroller Assembly Language is a combination of English like words called Mnemonics and Hexadecimal codes. It is also a low level language and requires extensive understanding of the architecture of the Microcontroller.
How the DPTR can be decremented in 8051?
2 Answers. The 8051 microcontroller was built like tha, the instruction for decrementing the 16-bit data pointer(DTPR) is not provided. The only way to decrement the datapointer is to decrement the low and high byte separately.
What is difference between PC DPTR in 8051?
Other storage registers in an 8051 microcontroller are the accumulator, the stack pointer (SP), R register, B register and the program counter (PC). The Data Pointer in 8051 microcontrollers in short form DPTR is the only 2-byte register a user can access.
What is the difference between PC and DPTR?
The PC is pointing to the current instruction, so a PC-relative address would be useful for a nearby lookup table. On the other hand, the DPTR can be set independently to point to an arbitrary location in ROM, not necessarily near the program counter, so you can address locations not within [PC, PC + 256).
What is assembler in microcontroller?
An assembler is a program that translates symbolic code (assembly language) into executable object code. This object code can be executed with a 80C51-compatible microcontroller. An assembly program has three parts: Machine instructions – Code the machine can execute.
What happen when RET is used?
Description. The ret instruction transfers control to the return address located on the stack. This address is usually placed on the stack by a call instruction. Issue the ret instruction within the called procedure to resume execution flow at the instruction following the call .
What is difference between RET and IRET?
The IRET instruction is used to exit from an interrupt procedure while RET is to return from an subroutine. IRET is similar to RET except that RET will just pop two bytes to PC while IRET will reset the interrupt enable (IEN) flip flop and two bytes will be popped from the stack.
Can DPTR be decremented?
The high- and low-bytes of the DPTR must be decremented separately; however, the high-byte (DPH) is only decremented if the low-byte (DPL) underflows from 00H to FFH.
What is DPH and DPL in 8051?
In 8051 assembly code, this address pointer is called DPTR. Because the 8051 is an 8-bit microcontroller, the 16-bit data pointer is controlled by two byte-wide registers, DPH (data pointer high-byte) and DPL (data pointer low-byte).
What is meant by DPTR in 8051 microcontroller?
Both can do the same work but they both are used in different scenarios. a counter is normally used to count number of clock cycles ,interrupt is raised,or simply any changes occurred based on the programmer’s choice. In Counter mode , 8051 count number of pulses.
Which is the data pointer on the 8051?
The Data Pointer (DPTR) is the 8051’s only user-accessible 16-bit (2-byte) register. The Accumulator, R0–R7 registers and B register are 1-byte value registers. DPTR is meant for pointing to data. It is used by the 8051 to access external memory using the address indicated by DPTR.
What are the different types of registers in 8051?
The most widely used registers of the 8051 are A (accumulator), B, R0-R7, DPTR (data pointer), and PC (program counter). All these registers are of 8-bits, except DPTR and PC. Storage Registers in 8051 We will discuss the following types of storage registers here −
When does the 8051 initialize the SP address?
This order of operation is important. SP will be initialized to 07h when the 8051 is initialized. If a value is pushed onto the stack at the same time, the value will be stored in the internal RAM address 08h because the 8051 will first increment the value of SP (from 07h to 08h) and then will store the pushed value at that memory address (08h).