Code for TRF7970AEVM in Direct Mode 0

Hello Josh

I have been reviewing the code "MSP430 Mifare Firmware Development Package" and it is for Transmitting in SDM and Receiving in DM1. What if I need the firmware for Receiving in DM0? (Regarding my application, I need to continuously read data in Direct Mode Zero)

Thank you very much, in advance.

Hi Politeknik,

Why do you specifically need to use DM0? Are you working with Mifare Classic, or is this for some other proprietary RFID tag? I don't understand why you would need to continuously read data in DM0.

We use the SDM/DM1 combination because it is simply far superior to DM0 in terms of usability, and provides a far more robust method for communicating with tags such as a Mifare Classic that will not work with the TRF79xx's DM2 mode.

For DM0, you would need a clock tolerance of +/- 0.1%, a clock at 13.56MHz or faster as long as it is a multiple of 13.56MHz, and also handle the Manchester decoding/encoding of the raw data.

Hello Ralph

Thank you very much for your kind reply.

Here is my application:
I have a medical implant as a transponder and the TRF79xx helps me in two fields:
(1) It powers up the battery-less implant (via Inductive Power Transfer) and so, make it functional
(2) It reads the data which is continuously sent by the implant

Since the size of the implant ASIC is very limited, we have decided to add just some SOF (start of frame) and EOF (end of frame) to the data at the transponder side and send them to the RFID in DM0.

I hope I explained it in a clear way
What do you think?

Hi Politeknik,

Thanks for those additional details. What sort of modulation scheme will you be using for this?

If you use a scheme AND a timing spec that follows any of the RFID specifications our TRF79xx supports (ISO14443, ISO15693 etc.) then you could actually use DM1 to handle this, and it would be a very stable solution. I would recommend doing this if at all possible. You wouldn't need to send any of the RFID commands or anything like that, simply just meet the modulation/timing requirements that are drawn out by those standards and DM1 will work just fine, so it should keep your overhead very small still.

If not, then you will need to at least use a modulation scheme supported by the TRF79xx receivers, which are the ASK/OOK modulations supported by the chip settings of Bits 2-0 in Register 0x09, you can find these on Table 6-36 of the TRF7970A datasheet (Page 63). If you don't meet any of those modulation types, even DM0 will not decode your data.

Hello Ralph

Thanks a lot for your beneficial and informative reply. I really appreciate that.

As you mentioned on the last paragraph, I am going to use the ASK/OOK. Just as the last question, "MSP430 Mifare Firmware Development Package" is for receiving in DM1. would you please share the relevant firmware for receiving in DM0 with me?