Broadcasting a custom binary string via the TRF7960

Jeyan Oorjitham

Other Parts Discussed in Thread: TRF7960, TRF7960A, MSP430F2370

Hello, I am currently working as a research assistant for Dr. Xiaomin Ma at Oral Roberts University. Since I am new to working on hardware, I have many questions.

We would like to have each node in a wireless sensor network consist of an MCU connected to a TRF7960. Our first objective would be to have one node use its TRF7960 to broadcast a custom binary string to all the other nodes within its communication radius. We then hope to implement and test various MAC protocols using the set of nodes.

We would load a new MAC protocol into the MCU, then run an experiment where the MCUs randomly sent binary string "packets" to each other and recorded the number of packets received, dropped, etc. From these metrics, we would evaulate the MAC protocol under consideration.

Can you give me any feedback on the feasibility of these ideas? Does it seem possible? What sort of issues might we encounter? (We are considering HF RFID transmissions for their smaller transmission radius. Our target transmission radius is ~10-20cm, with flexibility.)

For this application, it seemed that we might need to use Direct Mode 0 or Direct Mode 1 to bypass the TRF7960's built-in anticollision features and rely entirely on the MCU for media access control. Is this method appropriate?

Also, I found the "Implementation of ISO14443A Anti Collision Sequence in the TI TRF796x" document might be very useful in designing our own MAC protocols.

Are there any guides/tutorials/pictures on interfacing the TRF7960 with an MCU? The datasheet seems to contain some useful circuit diagrams and schematics. Are all the components shown for processing the antenna signal needed if we are not directly aiming for ISO compliance?

What affect would using a simple coil of wire as an antenna or not using an antenna at all have on the transmission radius?

Also, I noticed the TRF7960EVM GUI source code for PCs. Is there any available source code designed to run on an MCU and control the TRF7960?

Thank you,
Jeyan Oorjitham

over 14 years ago

0 Josh Wyatt over 14 years ago

TI__Guru* 91206 points

Jeyan -

please let me understand your goal here...are you attempting to create another version of NFC? Using the RI-R6C-001A, the TRF7960 or the TRF7960A, you could make your own protocol up and drop the part(s) into AFE only mode and do exactly what you want here - but seems like possibly alot of firmware effort. What is your timeframe? would you be interested in using an IC that already has peer to peer "built in"?

At any rate, have a look at the TRF7960TB eval board and schematic on the product folder below...this is i think what you would want to use here - it is set up for SPI w/SS only and has all the pins you need brought out to the headers for doing all the Direct Modes. http://focus.ti.com/docs/toolsw/folders/print/trf7960tb.html

The source code (for MSP430F2370) is also available on the TRF7960 product folder. We also have source code for LM3S9B96 Cortex M3 in case you want to use that - it also has Direct Mode code example in there for doing the popular non-ISO standard but ISO14443A like ticketing/transit cards.

http://focus.ti.com/docs/toolsw/folders/print/sw-dk-lm3s9b96-em2-trf7960-14443a.html

http://focus.ti.com/docs/toolsw/folders/print/dk-em2-7960r.html

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Broadcasting a custom binary string via the TRF7960