Digital to Analog Converter

Discussion in 'The Projects Forum' started by wheetnee, Nov 1, 2009.

  1. wheetnee

    Thread Starter New Member

    Oct 1, 2009
    28
    0
    Hi,

    for my class I have to use a Digital to Analog Converter and I'm using the
    DAC MCP4922 (12-Bit DAC with SPI™ Interface) , I did some research online, and I know it coverts signals of 0s and 1's into a analog signal (current/voltage). I need to obtain a voltage ouput from this.

    My power supply gives 12V DC, and because the DAC has a rail to rail output, I will get 12V output from it and when connected to the amplifier, I can amplify this voltage output.

    My professor says I don't have to worry about it being R/2nR or R/2R DAC, but I have to focus on what and where I input my binary signals on the DAC, and how the SPI is interfaced. We are writing our functions on matlab then put it in VHDL ( using Altera ). But I'm confused where/what my inputs (in binary) go into my DAC. How do I get the 0/1 input?
    Are there any tutorials on how to use the DAC in a circuit( either than the DATA sheet)
    And also, is the SPI stuff interfaced through programming
    The 3 pins that make up the SPI are
    -Clock
    - Chip Select
    - Serial Data input

    What do they do? As time ticks, you can change the wave of the sound?

    thanks,



    *edit*

    i went through overviews of the SPI and the data sheet of MCP4922, but I am still confused. I have an altera board, do I program the altera board to send signals to the DAC THROUGH SPI? the SPI just reads data and transmits data right? I'm confused on the whole operation of the DAC and SPI combined.
     
    Last edited: Nov 5, 2009
  2. beenthere

    Retired Moderator

    Apr 20, 2004
    15,815
    282
  3. wheetnee

    Thread Starter New Member

    Oct 1, 2009
    28
    0
    yes i read that
    but thta explains theory,
    I don't understand how to use it itself, like the actaul chip.
    i canot determine what kind of DAC it is from the data sheet
     
  4. DumboFixer

    Active Member

    Feb 10, 2009
    219
    34
    If you are using the 8 pin version then your analogue voltage will be on pin 8 and if you are using the 14 pin chip then your 2 outputs will be on pins 14 and 10.

    The data sheet says it uses a resistive chain so I assume that is 9or is similar to) the R2R method (I am happy to be corrected on this).

    To use it, simply send the digital value via the SPI protocol and you will get the analogue voltage output.
     
  5. beenthere

    Retired Moderator

    Apr 20, 2004
    15,815
    282
    The data sheet indicates that it is a dual DAC. There are two independent DAC's in the package. As indicated, they are voltage output. There are several illustrations of circuits and the I/F to a PIC microcontroller.

    Read the data sheet carefully - all the information you need is there.
     
  6. wheetnee

    Thread Starter New Member

    Oct 1, 2009
    28
    0
    what is the Serial Peripheral Interface excatly and what does it do?
     
  7. beenthere

    Retired Moderator

    Apr 20, 2004
    15,815
    282
  8. wheetnee

    Thread Starter New Member

    Oct 1, 2009
    28
    0
    i have an altera board to programm it for it to connect to the DAC

    is thre any simple schematics i can use to test out the DAC?

    I'm still confused about the SPI. How do i excatly interface it with the DAC?
    Which one is the slave device/master device?
     
Loading...