<< Chapter < Page Chapter >> Page >

The ports connected to the LEDs, buttons and buzzer are then initialized.

Finally, the interrupts are activated, and the application waits for the execution of one of two interrupts.

The Basic Timer1 interrupt executes at a frequency of once every second. When this interrupt is occurs, it begins by switching the state of LED1 and LED2. Afterwards, it accesses the memory to fetch the next musical note to be performed. The routine ends with memory pointer management.

The Port 1 ISR begins by evaluating the source of the interrupt. The sound volume is reduced if the button SW1 is pressed. The sound volume is increased if button SW2 is pressed.

System configuration

Timer_b

It is the responsibility of Timer_B to produce the PWM signal that activates the Buzzer. Timer_B counts until the value contained in the TBCCR0 register is reached. It does not generate an interrupt, and must be sourced by SMCLK clock signal:

TBCTL = TBSSEL_2 | CNTL_0 | TBCLGRP_0 |MC_1 | ID_0;

Each PWM signal produced by Timer_B corresponds to a musical note. The relationship between the frequency and the musical note is given in Table 1.

Note SI0 DO RE MI FA SOL LA SI DO2
Freq [Hz] 503 524 587 662 701 787 878 1004 1048

Timer_B has a frequency clock input equal to 7.995392 MHz.

The value to write in the TBCCR0 register in order to generate the desired frequency is:

// TBCCR0 value of the musical notes #define SI0 15895#define DO 15258 #define RE 13620#define MI 12077 #define FA 11405#define SOL 10159 #define LA 9106#define SI 7963 #define DO2 7629TBCCTL4 = OUTMOD_3; // CCR4 interrupt enabledTBCCR4 = space[0]/2;

Timer_a configuration

TACTL = TASSEL_2 |MC_2 | ID_0 | TAIE; // SMCLK, continuous mode up to 0xffff TACCTL1 = CM1 | CCIS_0 | CAP | CCIE;// Capture on rising edge, Cap mode,// Cap/Com int. enable, TACCR1 input signal selected//********************************************************* // Timer A ISR//********************************************************* #pragma vector=TIMERA1_VECTOR__interrupt void TimerA1_ISR (void) {switch (TAIV) {case TAIV_TACCR1: if (capture == 0){T1 = TACCR1; flag = 1;capture = 1; }else { if (flag == 1) {T2 = TACCR1; if (T2>T1) T = T2-T1;} else{TAR = 0; }capture = 0; flag = 0;} break; case TAIV_TACCR2: break;case TAIV_TAIFG:tick++; if (tick == 60){LCD_freq(); tick = 0;} if (flag == 1)flag = 0; break; default: break;} }

Basic timer1

The Basic Timer1 generates an interrupt once every second. It uses two counters in series, where the BTCNT2 counter input uses the BTCNT1 counter output divided by 256. The BTCNT1 counter input is the ACLK clock signal with a frequency of 32.768 kHz.

If BTCNT2 counter selected output is divided by 128, what is the time period associated with the Basic Timer1 interrupt? _________

What are the values to write to the configuration registers?

BTCTL = BTDIV | BT_fCLK2_DIV128; // (ACLK/256)/128 IE2 |= BTIE; // enable BT interrupt//*********************************************************// Basic Timer ISR. Run with 1 sec period //*********************************************************#pragma vector=BASICTIMER_VECTOR __interrupt void basic_timer_ISR(void){ unsigned int read_data; // read data from file , frequency in kHzP2OUT^=0x06; // toogle LED1 and LED2counter++;if (counter == 5){ counter = 0;read_data = 200; TBCCR0 = 7995392/read_data;TBCCR4 = TBCCR0/2; }}

I/o ports configuration

// SW1 and SW2 configuration (Port1) P1SEL&= 0x00; // P1.0 and P1.2 I/O P1DIR&= 0x00; // P1.0 and P1.2 as inputs P1IFG = 0x00;P1IES&= 0xFF // high-to-low transition interrupt P1IE |= 0xFF; // enable port interrupts// LED1 and LED2 configuration (Port2):P2DIR |= 0x06; // P2.2 and P2.1 as outputs P2OUT = 0x04; // LED1 on and LED2 off// Buzzer port configuration (Port3)P3SEL |= 0x20; // P3.5 as special function P3DIR |= 0x20; // P3.5 as digital output

Fll+ configuration

FLL_CTL0 |= DCOPLUS + XCAP18PF; //DCO+ set,freq=xtal*D*N+1 SCFI0 |= FN_4; // x2 DCO freq, 8MHz nominal DCOSCFQCTL = 121; // (121+1) x 32768 x 2 = 7.99 MHz

Analysis of operation

System clocks inspection

The MCLK, SMCLK and ACLK system clocks are available at ports P1.1, P1.4 and P1.5 respectively. These ports are located on the SW2, RESET_CC and VREG_EN lines, which are available on the H2 Header pins 2, 5 and 6. All these resources are available because the Chipcon RF module is not installed and SW2 is not used.

Using the Registers view, set bits 1, 4 and 5 of P1SEL and P1DIR registers to choose the secondary function of their ports, that is, configured as outputs. Connect an oscilloscope probe at these positions to monitor the clock signals.

What are the values measured for each of the system clocks?

ACLK: _____________________

SMCLK: ____________________

MCLK: _____________________

Tbccr4 unit output frequency

With the help of an oscilloscope, it is possible to evaluate the operation of the application. Alternatively, it is possible to listen to the sound produced. By removing jumper JP1 and connecting the oscilloscope to this pin, it is possible to view the PWM signal produced by the microcontroller. The duty-cycle can be reduced or increased by pressing the push buttons SW1 and SW2.

Port p1 interrupt source decoding

All Port P1 interrupt lines share the same interrupt vector. The decoding is done through the P1IFG register.

This process can be observed by entering a breakpoint at the first line of the ISR code.

Execute the application.

The application’s execution is suspended at the breakpoint by pressing either button SW1 or SW2. From this point onwards, run the lines of code step-by-step and observe changes in the register values.

Measurement of electrical current drawn

The power consumption was discussed in the previous point. The electrical power required by the system during operation is measured by replacing the jumper on the Header PWR1 by an ammeter, which indicates the electric current taken by device during operation.

What is the value read? __________

This example and many others are available on the MSP430 Teaching ROM.

Request this ROM, and our other Teaching Materials here (External Link)

Questions & Answers

where we get a research paper on Nano chemistry....?
Maira Reply
what are the products of Nano chemistry?
Maira Reply
There are lots of products of nano chemistry... Like nano coatings.....carbon fiber.. And lots of others..
learn
Even nanotechnology is pretty much all about chemistry... Its the chemistry on quantum or atomic level
learn
Google
da
no nanotechnology is also a part of physics and maths it requires angle formulas and some pressure regarding concepts
Bhagvanji
Preparation and Applications of Nanomaterial for Drug Delivery
Hafiz Reply
revolt
da
Application of nanotechnology in medicine
what is variations in raman spectra for nanomaterials
Jyoti Reply
I only see partial conversation and what's the question here!
Crow Reply
what about nanotechnology for water purification
RAW Reply
please someone correct me if I'm wrong but I think one can use nanoparticles, specially silver nanoparticles for water treatment.
Damian
yes that's correct
Professor
I think
Professor
Nasa has use it in the 60's, copper as water purification in the moon travel.
Alexandre
nanocopper obvius
Alexandre
what is the stm
Brian Reply
is there industrial application of fullrenes. What is the method to prepare fullrene on large scale.?
Rafiq
industrial application...? mmm I think on the medical side as drug carrier, but you should go deeper on your research, I may be wrong
Damian
How we are making nano material?
LITNING Reply
what is a peer
LITNING Reply
What is meant by 'nano scale'?
LITNING Reply
What is STMs full form?
LITNING
scanning tunneling microscope
Sahil
how nano science is used for hydrophobicity
Santosh
Do u think that Graphene and Fullrene fiber can be used to make Air Plane body structure the lightest and strongest. Rafiq
Rafiq
what is differents between GO and RGO?
Mahi
what is simplest way to understand the applications of nano robots used to detect the cancer affected cell of human body.? How this robot is carried to required site of body cell.? what will be the carrier material and how can be detected that correct delivery of drug is done Rafiq
Rafiq
if virus is killing to make ARTIFICIAL DNA OF GRAPHENE FOR KILLED THE VIRUS .THIS IS OUR ASSUMPTION
Anam
analytical skills graphene is prepared to kill any type viruses .
Anam
Any one who tell me about Preparation and application of Nanomaterial for drug Delivery
Hafiz
what is Nano technology ?
Bob Reply
write examples of Nano molecule?
Bob
The nanotechnology is as new science, to scale nanometric
brayan
nanotechnology is the study, desing, synthesis, manipulation and application of materials and functional systems through control of matter at nanoscale
Damian
Is there any normative that regulates the use of silver nanoparticles?
Damian Reply
what king of growth are you checking .?
Renato
What fields keep nano created devices from performing or assimulating ? Magnetic fields ? Are do they assimilate ?
Stoney Reply
why we need to study biomolecules, molecular biology in nanotechnology?
Adin Reply
?
Kyle
yes I'm doing my masters in nanotechnology, we are being studying all these domains as well..
Adin
why?
Adin
what school?
Kyle
biomolecules are e building blocks of every organics and inorganic materials.
Joe
how did you get the value of 2000N.What calculations are needed to arrive at it
Smarajit Reply
Privacy Information Security Software Version 1.1a
Good
Got questions? Join the online conversation and get instant answers!
Jobilize.com Reply

Get the best Algebra and trigonometry course in your pocket!





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