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Use the S1 button in the MSP430-EXP430FG4618 development tool and in the eZ430-RF2500 kit to toggle the state of LED1. You must use interrupts to catch the button press and you should ensure that the MSP430 is in Lower Power Mode 3 when is not in use.

Laboratory gpio: lab3 - toggle the led state by pressing the push button


The hands-on laboratory consists of configuring the I/O ports, setting up the input lines to read push buttons and the output lines to feed LEDs. The following exercises have been developed for the three hardware development tools.

The first to be discussed is the MSP-EXP430FG4618 Experimenter’s board. Modifications are later made to suit the other development boards. The main differences between the boards are related to the specific ports in which the buttons and LED are (or can be) connected. For the development of this laboratory, Code Composer Essentials v3 has been used.


By analysis of the schematics, determine to which port pin the push button is connected:

- Consult the MSP430FG4618/F2013 Experimenter’s Board User's Guide<slau213a.pdf>:

- Button S1 is connected to Port 1.0;

- Consult the eZ430-RF2500 Development Tool User's Guide<slau227a.pdf>:

- Button S1 is connected to Port 1.2;

- The eZ430-RF2500 uses a device in 2xx family, so you need to additionally configure the button as pull-up or pull-down, in the P1REN register.

Ports control registers:

- Set push button pin port as an input

- P1DIR: Port 1.0 is set as an input:

P1DIR&= ~0x01 // to force the pin setting to 0. It is uses an AND operation (&) between P1DIR and 0xFE

- Enable interrupts to this pin port;

- P1IE: Enable interrupt to port 1.0:

P1IE |= 0x01; // Interrupt Enable in P1.0

- PIIES: Call the port interrupt on a high-to-low transition:

P1IES |= 0x01; // P1.0 Interrupt flag high-to-low transition

- Configure the watchdog timer to prevent a PUC during the program execution;

WDTCTL = WDTPW | WDTHOLD; //Stop Watchdog Timer

- Enable Global Interrupts and configure low power mode 3;

_BIS_SR (LPM3_bits + GIE); //Low Power Mode with interrupts enabled

- Create a interrupt service routine, that includes:

- Toggle LED1 pin port;

- Delay for button debounce;

- Clear interrupt flag.

#pragma vector=PORT1_VECTOR __interrupt void Port_1 (void) {volatile unsigned int i; P2OUT ^= 0x04; // Toggle Port P2.2i=1500; // Delay, button debounce do (i--);while (i !=0); while (! (P1IN&0x01)); // Wait for the release of the button i=1500; // Delay, button debouncedo (i--); while (i !=0);P1IFG&= ~0x01; // Clean P1.0 Interrupt Flag }

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

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.
yes that's correct
I think
what is the stm
Brian Reply
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industrial application...? mmm I think on the medical side as drug carrier, but you should go deeper on your research, I may be wrong
How we are making nano material?
what is a peer
What is meant by 'nano scale'?
What is STMs full form?
scanning tunneling microscope
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Do u think that Graphene and Fullrene fiber can be used to make Air Plane body structure the lightest and strongest. Rafiq
what is differents between GO and RGO?
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
what is Nano technology ?
Bob Reply
write examples of Nano molecule?
The nanotechnology is as new science, to scale nanometric
nanotechnology is the study, desing, synthesis, manipulation and application of materials and functional systems through control of matter at nanoscale
Is there any normative that regulates the use of silver nanoparticles?
Damian Reply
what king of growth are you checking .?
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
yes I'm doing my masters in nanotechnology, we are being studying all these domains as well..
what school?
biomolecules are e building blocks of every organics and inorganic materials.
anyone know any internet site where one can find nanotechnology papers?
Damian Reply
sciencedirect big data base
Introduction about quantum dots in nanotechnology
Praveena Reply
what does nano mean?
Anassong Reply
nano basically means 10^(-9). nanometer is a unit to measure length.
do you think it's worthwhile in the long term to study the effects and possibilities of nanotechnology on viral treatment?
Damian Reply
absolutely yes
how did you get the value of 2000N.What calculations are needed to arrive at it
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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
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