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[SHONG.11]

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[Brian TIDAL]

Hi

my understanding of your use case is the following:

• probe an electric nerve signal
• convert its analog value to a digital value
• exchange this digital value through NFC to a equipment that would record the different values.

If my understanding is correct, the following proposal could be used

You can use for example the ST25DV-DISCOVERY kit to prototype your application. Some test points seems to be available to connect to an ADC analog input channel (for example TP4).

Rgds

BT

[SHONG.11]

appreciate for quick and king response.

1.is that DVkit for all the ST25 family product line?

2. does ST25RU3993 also can be work for our purpose as well?

[Brian TIDAL]

​Hi,

ST25DV-DISCOVERY is is based on NFC ST25DV04K Dynamic tag. Anyway, this can be used for protoyping applications for ST25DV-I2C series Dynamic NFC Tags.

ST25RU3993 is an UHF reader used to read/write UHF tags. Do you plan to store you records inside a tag? Something like:

(or like this in case of NFC)

Feel free to clarify your use case:

• data storage; in a tag or in a device attached to the reader?
• reading distance (impact on choice between UHF and NFC)
• data volume,
• etc.

Rgds

BT

[SHONG.11]

1. data storage : in a tag might be better i think. since we will gonna implant the devices into the mouse, it cannot be ejected unless the test is over
2. reading distance is not a real crucial factor for us (think 1 meter might be enough for now), but in case when we use 13.56MHz devices, The size of the antenna can be the issue.
3. data volume : it is pretty hard to say but the reason why i think tag can be the better place to store the data is, want to show the data as a real time. what we want is when we excite or give a stimulate the devices, show the signal for a real-time.
4. the another issue is, in case of active RFID MCU, the power can be the issue, since we will not use a battery but wireless power transfer method.

Once again really appreciate for swift and kind response

[Brian TIDAL]

Hi,

Some comment:

• reaching 1m distance with a 13.56 MHz NFC device is not so realistic. NFC reading distance is usually few centimeters (NFC-A/B/F) up to few 10 of cm (NFC-V)
• how do you plan to store the data into a passive tag? you need a device to do the Analog to Digital conversion and then this device would need to write into the tag memory: by which mean? How do you plan to power this device?

Rgds

BT

[SHONG.11]

1. if the signal can penetrate the tissue, 10cm is fine I think. but for that reason also think about the 900MHz as well
2.  Well for ST products RFID, as a first, what i've thought about is, just want to see the signal for back-scattering. by doing this, I thought we can see the signal by tagging it and record it at the same time.
3. please tell me if there is wrong. i willing to learn from you.
   1. 900MHz RFID : Since it can cover wide range of distance just tagging it constantly and record signals by computer or phone.
   2. 13.56MHz RFID : Since it is active RFID, store the data on device and receive it when we want to see the data (with wireless communication). or see the signal like 900MHz only with short distance (back-scattering).
4. the current method what I think about feed the MCU is inductive coupling. if i have to

[Brian TIDAL · Accepted solution]

Hi,

13.56 MHz RFID communications are intended to communicate between a Poller (Reader/Writer) and a Listener (basically a tag). The Poller emits a 13.56 MHz field. This field inductively couples to the Listener to transfer power and is modulated for communication. The Poller modulates the amplitude of the alternating magnetic field strength with modulation pulses in order to transmit data to the Listener. The Listener loads the alternating magnetic field with a modulated subcarrier signal (load modulation) in order to transmit data to the Poller. This follows some standards (such ISO14443 or ISO15693).

A 13.56 MHz tag is basically an EEPROM memory connected to a 13.56 MHz RF interface. This RF interface powers the EEPROM memory when the field is present, receives commands from the poller, processes those commands such a s read or write part of the EEPROM memory and sends a response to the poller.

When using a simple tag, the EEPROM memory can only be accessed by the Poller through the RF interface thanks to standardized commands. If you want to sample an electric nerve signal, there is no mean to directly store the sampled values inside a simple tag (i.e. a tag having only an RF interface)...

If you want to write your data into the tag memory, you need a second interface usually I2C interface connected to a MCU that will sample the nerve electric signal, convert it to a digital value and write it inside the EEPROM. The values can be read latter on by a standard reader. Such tags are called Dynamic tags or dual interface tags.

I would suggest you have a look on M24LR-DISCOVERY kit: the M24LR board includes a dynamic tag and an STM8 MCU. It is battery-less and is powered by RFID readers. Once the field is ON, thanks to the energy harvesting, the on-board STM8 MCU is powered on and can display some informations on the LCD (voltage, temperature and the content of the NDEF text in the tag memory). I believe this can fit with your needs.

I have no specific knowledge on 900 MHz RFID.

Rgds

BT