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Using the DMA controller included in the MSP-EXP430FG4618 Development Tool transfer a sinusoidal wave to the DAC12_0's output. Timer_A operates in upmode with TACCR1 loading DAC12_0 on rising edge and DAC12_0IFG triggering next DMA1 transfer. DAC12_0 uses internal 1.5V reference.

Laboratory dma: lab2 - sinusoidal waveform generator


This laboratory gives an example of the use of the DMA peripheral available in the MSP-EXP430FG4618 Development Tool. It requires the configuration of the DMA Source and Destination Addresses Registers, DMA Size Address Register; DMA Control Registers, DMA Channel 0 Control Register, DAC12 control register and Timer_A control register in order to generate a sinusoidal waveform.


This laboratory ( Lab2_DMA.c ) uses the DMA controller to automatically transfer data between data memory and the DAC12 data register. A sinusoidal waveform is produced at the output of the DAC, without CPU intervention.


This laboratory uses the following peripherals:

- DMA controller;

- DAC;

- ADC (reference generator: V REF+ );

- Timer_A;

- Low power mode.

Software application organization

The successive samples needed to produce the sinusoidal waveform using the DAC are stored in the data vector Sin_tab , which contains 32 points:

//--------------------------------------------------------- // 12-bit Sine Lookup table with 32 steps//--------------------------------------------------------- int Sin_tab[32]= {2048, 2447, 2831, 3185, 3495, 3750, 3939, 4056, 4095, 4056, 3939, 3750, 3495, 3185, 2831, 2447,2048, 1648, 1264, 910, 600, 345, 156, 39, 0, 39, 156, 345, 600, 910, 1264, 1648};

The software begins by disabling the watchdog timer, followed by activating the internal reference voltage V REF+ . The source and destination registers of the data vector to be transferred by the DMA channel are loaded into the data vector Sin_tab (source) address and with the DAC12 data register (destination) address. There are 32 data values to be transferred.

The data transfer is initiated whenever the DAC12IFG flag is enabled. In this application, the DAC interrupt should be disabled.

The DMA controller is configured to operate in repeat mode, to transfer a word whenever the previous event occurs. The data source address is set to increment after each transfer, while the destination address must remain constant.

The timer is set to generate the PWM signal through the capture/compare unit TACCR1. SMCLK is the clock signal that counts up to the value in the TACCR0 register.

Finally, the settings and interrupts are enabled and the device enters into low power mode LPM0.

System configuration

Dac12 reference voltage activation

The DAC12 requires a reference voltage. One of the options is to use the internal voltage V REF+ . Set the ADC12CTLO register to activate this voltage:

ADC12CTL0 = REFON; // Internal reference

Dma controller configuration:

Configure the registers DMA0SA (source), DMA0DA (destination) and DMA0SZ (size) to transfer 32 words between the source vector Sin_tab and the DAC12_0DAT data destination register:

DMA0SA = (void (*)( ))&Sin_tab; // Source block addressDMA0DA = (void (*)( ))&DAC12_0DAT; // Destination single addressDMA0SZ = 0x20; // Block size

Configure the register DMACTL0 to provide a data transfer whenever the DAC12IFG flag is set:

DMACTL0 = DMA0TSEL_5; // DAC12IFG trigger

Configure the register DMA0CTL to carry out a repeated simple data transfer, increasing the data source address:

DMA0CTL = DMADT_4 | DMASRCINCR_3 | DMAEN; // Repeated single transfer,// DMA source address increment, // since DMASRCBYTE = 0, the source address increments by// two (word-word)

Setup dac12

The DAC12 will update its output whenever there is the activation of the signal TA1. The DAC full-scale should be 1x reference voltage. Choose a medium relationship between the DAC’s current and average conversion speed:

DAC12_0CTL = DAC12LSEL_2 | DAC12IR | DAC12AMP_5 | DAC12IFG | DAC12ENC; // Rising edge of Timer_A.OUT1 (TA1),// DAC12 full-scale output: 1x reference voltage, // Input and output buffers: Medium freq./current,// Enable DAC12

Timer_a configuration

Timer_A is responsible for synchronizing data transfers between memory and the DAC12. The Timer_A input receives as the SMCLK signal (1.048576 MHz) and must have a 30 msec counting period. What value needs to be written to TACCR0, in order to achieve this counting period:

TACCR0 = 32-1; // Clock period of TACCR0 TACTL = TASSEL_2 | MC_1; // SMCLK, continuous mode

The capture/compare unit TACCR1 should generate a PWM signal in set/reset mode. Configure the unit appropriately:

TACCTL1 = OUTMOD_3; // TACCR1 set/reset TACCR1 = 20; // TACCR1 PWM Duty Cycle

Analysis of operation

The verification of this laboratory is achieved by using an oscilloscope probe to monitor the output of the DAC12 Channel 0, available on header 8 pin 6.

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
nanopartical of organic/inorganic / physical chemistry , pdf / thesis / review
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..
Even nanotechnology is pretty much all about chemistry... Its the chemistry on quantum or atomic level
no nanotechnology is also a part of physics and maths it requires angle formulas and some pressure regarding concepts
Preparation and Applications of Nanomaterial for Drug Delivery
Hafiz Reply
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.
yes that's correct
I think
Nasa has use it in the 60's, copper as water purification in the moon travel.
nanocopper obvius
what is the stm
Brian Reply
is there industrial application of fullrenes. What is the method to prepare fullrene on large scale.?
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
how nano science is used for hydrophobicity
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
analytical skills graphene is prepared to kill any type viruses .
Any one who tell me about Preparation and application of Nanomaterial for drug Delivery
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.
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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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