• State Resolved
  • Locked Locked
  • Replies 14 replies
  • Subscribers 57 subscribers
  • Views 3338 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

csma/ca implementation

kenfreeM
Expert 1030 points
Other Parts Discussed in Thread: CC2520, MSP430F5438A, TIMAC, Z-STACK, SMARTRFTM-STUDIO

how to implement csma/ca algorithm using msp430f5438a+cc2520 in IAR for msp430 workbench

  • 0
    Guru 735685 points

    If you use Z-Stack or TIMAC, CSMA/CA has been implemented.

  • 0 in reply to YiKai Chen
    TI__Genius 16570 points

    Correct. CSMA-CA is something that is specified in 802.15.4 specification. As ZigBee and TI-MAC use an 802.15.4 standard, CSMA/CA handling is taken care of in the stack itself.

    Thanks,

    TheDarkSide

  • 0 in reply to YiKai Chen
    Expert 1030 points

    yes

    i am using TIMAC.....i need to send data from one node to another using csma/ca ...if i send data using csma/ca where can i see output ....where can change csma/ca modifications in the TIMAC code

    -my main task is 

    --Data transfer between Two MSP430F5438A Experimental boards using IEEE 802.15.4 standard Frame Formats
  • 0 in reply to kenfreeM
    Expert 1030 points

    i am using beacon enabled mode...how to initialize beacon frame in csma/ca..because slotted csma/ca is beacon enabled mode

  • 0 in reply to TheDarkSide
    Expert 1030 points

    how can i check csma/ca in TIMAC code 

  • 0 in reply to kenfreeM
    TI__Genius 10650 points

    Hello Naresh Babu,

    For your question:

    -my main task is 

    --Data transfer between Two MSP430F5438A Experimental boards using IEEE 802.15.4 standard Frame Formats
     
    I would recommend using the TIMAC-1.5.0 from http://www.ti.com/tool/timac&DCMP=HPA_RFIC_General&HQS=Other+OT+timac
    Then you can refer to the document MAC Sample Application Software Design section 4 to understand how to start either a beacon enabled or a non-beaconed network. And then how to join the network and start sending data from the PAN Coordinator to devices and vice versa. TIMAC follows the IEEE 802.15.4 standard for the data communication.
     
  • 0 in reply to Suyash Jain
    TI__Genius 10650 points

    Also for your another question: 

    i am using beacon enabled mode...how to initialize beacon frame in csma/ca..because slotted csma/ca is beacon enabled mode

    Acknowledgment and beacon frames are sent without using a CSMA-CA mechanism as per IEEE 802.15.4 specification. But when using TIMAC the data frames will be sent using the CSMA-CA, application does not have to do any thing for this, TIMAC stack implement the CSMA-CA functionality. 

    Hope this helps. Thanks.

  • 0 in reply to Suyash Jain
    Expert 1030 points

    how to check/see whether slotted csma/ca is properly working or not ?

    -> where can i change modifications like slotted or unslotted csma/ca

    please help me anybody.

    thanks in advance

  • 0 in reply to kenfreeM
    Expert 1030 points

    how many nodes are need to checking whether slotted csma/ca working or not.....what is the frequency and channel number ???

    please help me.

  • 0 in reply to kenfreeM
    TI__Genius 16570 points

    Hi,

    the CSMA logic and code are, for the MSP430+2520 configuration, handled in mac_dualchip_tx.c module.

    As you can see in this module, the unslotted and slotted management is done through a callback function that is called when the backoff timer times out, calling the corresponding function that performs the channel listening (or CCA).

    Timer resources are used to count the backoff time.

    CCA is performed in dualchipTxUnslottedCsmaCca for the unslotted case, while it is done in dualchipTxSlottedCsmaCca() for the slotted mode.

    Backoff time is set in txCsmaPrep() function in mac_tx.c module, which is valid for both unslotted and slotted

    The radio channel can be set using MAC_MlmeSetReq() API, and you can choose all channels available in 802.15.4 (11-26).  Please see mac_api.h module and check out MAC_CHAN_XXX.

    Once you set the corresponding channel using that API, then all the MAC activity (Rx/Tx, including therefore the CCA) will be done on that channel.

    All nodes must implement CSMA-CA according to 802.15.4 standard. MinBE and MaxBE parameters and number of backoffs, which control respectively backoff exponent values and max number of backoff retries, can be set by the user, through the same API MAC_MlmeSetReq() API.

    Please check standard PIB Get and Set Attributes in mac_api.h

    You can check the actual backoff time by using some GPIO to time trace moment when CSMA is started (ie the actual call to macDualChipTxGoCsma) and in macTxDoneCallback(), when transmit is complete. You should see that before transmitting the time is spent randomly in CSMA+CCA, depending also on traffic channel conditions

    We do not recommend you to change the CSMA code mechanics. You may want to change the parameters of the CSMA according to your application needs but if that is the case, as suggested, please use MAC_MlmeSetReq() API.

    I also recommend you check out 802.15.4 MAC API document in \Documents\API fodler of your TI-MAC install

    Thanks,

    TheDarkSide

  • 0 in reply to TheDarkSide
    Expert 1030 points

    thank you sir,

    now i got some idea...finally one doubt

    ->can i change in mac_tx.c  MacMinBE and MacMaxBE parameter values...and then for checking purpose how many nodes are needed(i am having  msp430f5438a+cc2520 boards)

  • 0 in reply to kenfreeM
    TI__Genius 16570 points

    if you want to change MinBe and MaxBE, please use MAC_MlmeSetReq() API as suggested.

    For testing, you just need two nodes. One which is the device under test, and the second which will be a signal generator that creates the interference. To control the node that creates the interference, you can use SmartRFSTudio with CC25xx devices (http://www.ti.com/tool/smartrftm-studio) or basic SW examples (http://www.ti.com/lit/zip/swrc090) 

    Thanks,

    TheDarkSide

  • 0 in reply to TheDarkSide
    Expert 1030 points

    smartRf studio already installed

    msp430f5438a is suffient or any more nodes are need ...could you tell me the steps for checking csma/ca channel accessing method (signal)...my project last date is coming 28th

    please help me

  • 0 in reply to TheDarkSide
    Expert 1030 points

    thank u very much sir