<< Chapter < Page Chapter >> Page >

Central processing unit (msp430x cpu)

Main features of the msp430x cpu architecture

The MSP430X CPU extends the addressing capabilities of the MSP430 family beyond 64 kB to 1 MB. To achieve this, there are some changes to the addressing modes and two new types of instructions. One type of new instructions allows access to the entire address space, and the other is designed for address calculations.

The MSP430X CPU address bus is 20 bits, but the data bus is still 16 bits. The CPU supports 8-bit, 16-bit and 20-bit memory accesses. Despite these changes, the MSP430X CPU remains compatible with the MSP430 CPU, having a similar number of registers. A block diagram of the MSP430X CPU is shown in the figure below:

Msp430x cpu block diagram.

Although the MSP430X CPU structure is similar to that of the MSP430 CPU, there are some differences that will now be discussed.

With the exception of the status register SR, all MSP430X registers are 20 bits. The CPU can now process 20-bit or 16-bit data.

Msp430x cpu registers

R0 (pc) - program counter

Has the same function as the MSP430 CPU, although now it has 20 bits.

R1 (sp) - stack pointer

Has the same function as the MSP430 CPU, although now it has 20 bits.

R2 (sr) - status register

Has the same function as the MSP430 CPU, but still only has 16 bits.

Description of the sr bits.

R2 (cg1) and r3 (cg2) - constant generators

The registers R2 and R3 can be used to generate six different constants commonly used in programming, without the need to add an extra 16-bit word of code to the instruction. The constants below are chosen based on the bit (As) of the instruction that selects the addressing mode.

Values of constant generators.

Whenever the operand is one of these six constants, the registers are selected automatically. Therefore, when used in constant mode, registers R2 and R3 cannot be addressed explicitly by acting as source registers.

R4-r15 – general-purpose registers

These registers have the same function as the MSP430 CPU, although they now have 20 bits. They can store 8-bit, 16-bit or 20-bit data. Any byte written to one of these registers clears bits 19:8. Any word written to one of these registers clears bits 19:16. The exception to this rule is the instruction SXT, which extends the sign value to fill the 20-bit register.

The following figures illustrate how the operations are conducted for the exchange of information between memory and registers, for the following formats: byte (8 bits), word (16 bits) and address (20 bits).

The following figure illustrates the handling of a byte (8 bits) using the suffix .B.

Example: register-byte/byte-register operation.

The following figure illustrates the handling of a word (16-bit) using the suffix .W.

Example: register-word/word-register operation.

Example: register-word/word-register operation.

The following figure illustrates the manipulation of an address (20 bits) using the suffix .A.

Example: register - address-word operation.

Example: address-word - register operation.

Request the MSP430 Teaching ROM Materials here (External Link)

Questions & Answers

what is mutation
Janga Reply
what is a cell
Sifune Reply
how is urine form
Sifune
what is antagonism?
mahase Reply
classification of plants, gymnosperm features.
Linsy Reply
what is the features of gymnosperm
Linsy
how many types of solid did we have
Samuel Reply
what is an ionic bond
Samuel
What is Atoms
Daprince Reply
what is fallopian tube
Merolyn
what is bladder
Merolyn
what's bulbourethral gland
Eduek Reply
urine is formed in the nephron of the renal medulla in the kidney. It starts from filtration, then selective reabsorption and finally secretion
onuoha Reply
State the evolution relation and relevance between endoplasmic reticulum and cytoskeleton as it relates to cell.
Jeremiah
what is heart
Konadu Reply
how is urine formed in human
Konadu
how is urine formed in human
Rahma
what is the diference between a cavity and a canal
Pelagie Reply
what is the causative agent of malaria
Diamond
malaria is caused by an insect called mosquito.
Naomi
Malaria is cause by female anopheles mosquito
Isaac
Malaria is caused by plasmodium Female anopheles mosquitoe is d carrier
Olalekan
a canal is more needed in a root but a cavity is a bad effect
Commander
what are pathogens
Don Reply
In biology, a pathogen (Greek: πάθος pathos "suffering", "passion" and -γενής -genēs "producer of") in the oldest and broadest sense, is anything that can produce disease. A pathogen may also be referred to as an infectious agent, or simply a germ. The term pathogen came into use in the 1880s.[1][2
Zainab
A virus
Commander
Definition of respiration
Muhsin Reply
respiration is the process in which we breath in oxygen and breath out carbon dioxide
Achor
how are lungs work
Commander
where does digestion begins
Achiri Reply
in the mouth
EZEKIEL
what are the functions of follicle stimulating harmones?
Rashima Reply
stimulates the follicle to release the mature ovum into the oviduct
Davonte
what are the functions of Endocrine and pituitary gland
Chinaza
endocrine secrete hormone and regulate body process
Achor
while pituitary gland is an example of endocrine system and it's found in the Brain
Achor
what's biology?
Egbodo Reply
Biology is the study of living organisms, divided into many specialized field that cover their morphology, physiology,anatomy, behaviour,origin and distribution.
Lisah
biology is the study of life.
Alfreda
Biology is the study of how living organisms live and survive in a specific environment
Sifune
Got questions? Join the online conversation and get instant answers!
Jobilize.com Reply

Get Jobilize Job Search Mobile App in your pocket Now!

Get it on Google Play Download on the App Store Now




Source:  OpenStax, Teaching and classroom laboratories based on the “ez430” and "experimenter's board" msp430 microcontroller platforms and code composer essentials. OpenStax CNX. May 19, 2009 Download for free at http://cnx.org/content/col10706/1.3
Google Play and the Google Play logo are trademarks of Google Inc.

Notification Switch

Would you like to follow the 'Teaching and classroom laboratories based on the “ez430” and "experimenter's board" msp430 microcontroller platforms and code composer essentials' conversation and receive update notifications?

Ask