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Using the MSP-EXP430FG4618 Development Tool establish a connection between two MSP430's via the I2C bus. The master receives one byte from the slave. This is the master code. It receives a single byte as soon as a button connected on P1.0 was pressed.

Laboratory communications: lab3 - echo test using i2c


The MSP430 contains built-in features for both parallel and serial data communication. This chapter describes the operation of these peripherals, and discusses the protocols, data formats and specific techniques for each type of data communication.

The communication modules available for the MSP430 family of microcontrollers are USART (Universal Synchronous/Asynchronous Receiver/Transmitter), USCI (Universal Serial Communication Interface) and USI (Universal Serial Interface). These provide asynchronous data transmission between the MSP430 and other peripheral devices when configured in UART mode. They also support data transmission synchronized to a clock signal through a serial I/O port in Serial Peripheral Interface (SPI) and Inter Integrated Circuit (I2C) modes.


This laboratory explores the USCI and USI communication interfaces in I 2 C mode. It uses the two MSP430 devices included on the Experimenter’s board: MSP430FG4618 as the master and the MSP430F2013 as the slave. The master receives a single byte from the slave as soon as a button connected to P1.0 is pressed.


This laboratory uses the USCI module of the MSP430FG4618 device and the USI module included in the MSP430F2013. Both units operate in I2C mode.

The interrupts on the slave unit are generated exclusively by the USI module. They are:

- START condition in the I2C bus;

- Data reception and transmission.

The interrupts on the master unit are provided by the USCI module. They are:

- Data reception;

- Interrupt on Port1.

The resources used are:

- USCI module;

- USI module;

- Interrupts;

- I/O ports.

Software application organization

The software architecture for this laboratory is shown in Figure 1.

The master task is composed of two interrupt service routines ( Lab3_Comm_1.c ):

- S1 switch service routine used to receive a new frame from the slave;

- USCI module interrupt service routine that reads the data sent by the slave.

Software architecture

For the operational capability of the slave unit based on the USI module, it is necessary to implement a state machine as shown in Figure 2. It is important to note that the states “RX Address” and “RX (N)ACK" are transient states that ensure the USI module is prepared for the next activity.

Slave state machine.

System configuration

Usci_b (master) control registers configuration

The connection via I 2 C bus will operate in the following mode:

- Address slave with 7-bit address;

- Master mode;

- Single master;

- USCI clock source is SMCLK;

The following control registers are configured based on these characteristics:

UCB0CTL0 = 0x0F; //UCB0CTL0 = UCA10 | UCSLA10 | UCMM | Unused | UCMST | UCMODEx | UCSYNC//UCA10 (Own address) = 0b ->Own address (7-bit) //UCSLA10 (Slave address) = 0b ->7-bit slave address //UCMM (Multi-master) = 0b ->Single master //Unused//UCMST (Master mode) = 1b ->Master mode //UCMODEx (USCI mode) = 11b ->I2C Mode //UCSYNC (Synchronous mode enable) = 1b ->SynchronousUCB0CTL1 = 0x81;//UCB0CTL1 = UCSSELx | Unused | UCTR | UCTXNACK | UCTXSTP | UCTXSTT | UCSWRST//UCSSELx (USCI clock source select) = 10b ->SMCLK //Unused//UCTR (Transmitter/Receiver) = 0b ->Receiver //UCTXNACK (Transmit a NACK) = 0b ->ACK normally //UCTXSTP (Transmit STOP condition) = 0b ->No STOP //UCTXSTT (Transmit START condition) = 0b ->No START //UCSWRST (Software reset) = 1b ->Enabled

Questions & Answers

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 to know photocatalytic properties of tio2 nanoparticles...what to do now
Akash Reply
it is a goid question and i want to know the answer as well
characteristics of micro business
for teaching engĺish at school how nano technology help us
Do somebody tell me a best nano engineering book for beginners?
s. Reply
there is no specific books for beginners but there is book called principle of nanotechnology
what is fullerene does it is used to make bukky balls
Devang Reply
are you nano engineer ?
fullerene is a bucky ball aka Carbon 60 molecule. It was name by the architect Fuller. He design the geodesic dome. it resembles a soccer ball.
what is the actual application of fullerenes nowadays?
That is a great question Damian. best way to answer that question is to Google it. there are hundreds of applications for buck minister fullerenes, from medical to aerospace. you can also find plenty of research papers that will give you great detail on the potential applications of fullerenes.
what is the Synthesis, properties,and applications of carbon nano chemistry
Abhijith Reply
Mostly, they use nano carbon for electronics and for materials to be strengthened.
is Bucky paper clear?
carbon nanotubes has various application in fuel cells membrane, current research on cancer drug,and in electronics MEMS and NEMS etc
so some one know about replacing silicon atom with phosphorous in semiconductors device?
s. Reply
Yeah, it is a pain to say the least. You basically have to heat the substarte up to around 1000 degrees celcius then pass phosphene gas over top of it, which is explosive and toxic by the way, under very low pressure.
Do you know which machine is used to that process?
how to fabricate graphene ink ?
for screen printed electrodes ?
What is lattice structure?
s. Reply
of graphene you mean?
or in general
in general
Graphene has a hexagonal structure
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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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