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Passive NFC/RFID Target

Hemant Kamat
Intellectual 275 points
Other Parts Discussed in Thread: TRF7970A, TRF7960A, SIMPLICITI, TMS37157

I am designing a peer-to-peer system using NFC devices, such as TRF7970a, for Industrial Control. The concept is to have a NFC target mounted on the end point that can communicate with a hand held controller. The target will not have its battery but will be powered on by the RF field of the controller when the controller is in the vicinity of the target. I have the following questions about the design:

1. How do I power the TRF7970a and the MCU(MSP430) from the RF field?

2. How can I achieve a range of about 1mtr  to 2 mtrs between the two RF7970a devices.

Thanks for the help.

Regards.

Hemant

  • 0
    TI__Mastermind 44140 points

    Hermant,

    1. You could use an external rectifier diode and regulator tied to the antenna to power the TRF7970A and MSP430 from the field.

    2. NFC is not intended to reach this type of range.  You should not expect more than a few inches range.  Even with large antenna sizes, I don't think you will get close to 1m.  If you are also using some of field to power the TRF7970A and MSP430, this will reduce range further. 

  • 0 in reply to Eddie LaCost
    Intellectual 275 points

    Thanks Eddie,

    1. Does the 7970A or 7960A not support powering the device and the MCU from the antenna?

    2. I think TRF7960a RFID would be an option for me for longer distances or use Zigbee based communication.

    Regards.

    Hemant

  • 0 in reply to Hemant Kamat
    TI__Mastermind 44140 points

    1.  Correct, this is not implemented in the TRF7960A or 70A devices.  It would need to be handled externally.  This feature will be added to our next generation NFC transceiver which is in definition stage right now. 

    2.   The TRF7960A does not include support for peer to peer mode.  It also will not offer any increased range over the TRF7970A.  The TRF79xx devices will not achieve 1m range.  Zigbee or similar would work for longer range.  We offer a free RF protocol stack called SimpliciTI which may be of use for simple communication.  This stack is available for several of our sub 1GHz and 2.4GHz radios.  Our eZ430-RF2500 and eZ430-Chronos kits allow you to evaluate this protocol for a low entry price.     

    http://www.ti.com/tool/simpliciti

    http://www.ti.com/tool/ez430-rf2500

    http://www.ti.com/tool/ez430-chronos

     

  • 0 in reply to Eddie LaCost
    Intellectual 275 points

    Eddie,

    Thanks for the information.

    While exploring possibilities in Energy Harvesting, I found I can use TMS37157 for powering the MCU from RF energy. Also, there is a possibility of using ANT processors in my application.

    I am now exploring use of either CC430 or ANT Processor  with TMS37157 for RF energy harvesting. I would appreciate any tips on furthering this.

    Regards.

    Hemant

  • 0 in reply to Hemant Kamat
    TI__Mastermind 44140 points

    Hemant,

    Yes, TMS37157 could allow you to harvest some energy from a LF(134.2kHz) field.  It will still be difficult to get much energy harvested at 1m range.  Will you be able to have the LF transmitter closer to the TMS37157? 

    Will light be available?  You could also think about using solar like in the eZ430 kit below.

    http://www.ti.com/tool/ez430-rf2500-seh

  • 0 in reply to Eddie LaCost
    Intellectual 275 points

    Eddie,

    Now that I am aware of the distances that i can get between the transmitter and the receiver, i will go in for Zigbee based solution with energy harvesting from other physical parameters like light, heat or vibrations, if not RF.

    Thanks for the discussion.

    Regards.

    Hemant