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This is a dual port EEPROM that can be interfaced through an NFC antenna or Qwiic connector.
The board is 15mm X 15mm
It allows you to create an NFC tag that can be updated over I2C.
WIth standard NFC data formats you could share wireless connection details, URLs or contact information.
It can also be used for two way communication with a custom phone app.
If you are interested in this project and would like to get one of these, I'm including one in my QwiiKit that will soon be available at Crowd Supply:
Here is the board being accessed through the Qwiic connector:
There is also a video:
https://www.instagram.com/p/BoYK98fFmnP/?utm_source=ig_share_sheet&igshid=dxhbtd1k2cwn
See the instructions for more details on how to access the part through the Qwiic connector.
View this post on InstagramA post shared by Greg Steiert (@gregsteiert) on Sep 9, 2018 at 7:44am PDT
At 15mm X 15mm, I undershot the 1 square inch by quite a bit. I am updating the layout to utilize some of that space. I'm adding some mounting tabs, but they will be v-scored so that you can break them off if all you want is the 15 x 15 mm NFC tag.
I had underestimated how difficult it would be to attach the uDFN package, but after a trip to the Ctrl-H Hackerspace in Portland, and some time with their soldering station I was able to get a few up and running. Here is one with the LED lit up.
The parts and boards have been ordered. Everything should be here this week.
I followed the reference design for one of the antennas pretty closely. Let's see how much effect the components and connector in the middle have on performance.
Follow this link and get the application executable for your platform:
https://www.st.com/en/nfc/st25dv04k.html#sw-tools-scroll
STSW-ST25001 for Android or STSW-ST25IOS001 for iOS
Plug the Qwiic NFCPROM into the FPGA Helper using a Qwiic cable and run this python script on the FPGA Helper board:
greg
import board
import busio
i2c = busio.I2C(board.SCL, board.SDA)
while not i2c.try_lock():
pass
result = bytearray(32)
i2c.writeto(83, bytes([0x00, 0x00]), stop=False)
i2c.readfrom_into(83, result)
print(result)
If you save that to the board as boot.py, you should get a boot.txt file something like this:
Adafruit CircuitPython 4.0.0-alpha.1-4-gf09537b-dirty on 2018-10-01; Steiert Solutions FPGA Helper with samd21e18
boot.py output:
bytearray(b'\xe1@@\x05\x03\x14\xd1\x01\x10U\x03dei.steiert.net\xfe\xffCARD')
We are using the ST25DV04 with the idea that power can be supplied by the NFC antenna to power the board. Is this the idea here? Are you planning to power the EEPROM and whatever is connected to the Qwik connector via NFC?
Kevin Neubauer
sutfuf
Bob Coggeshall
Ultimate Robotics
The power output is only wired to an LED, not the Qwiic connector. The device is an I2C slave only.
It is basically an NFC tag that can be programmed or read over I2C through the Qwiic connector. For example, you could create an NFC tag that can be remotely updated. A restaurant could rotate random wifi passwords and share them through the NFC tag.
WIth a custom phone app you can implement two way communication with an mcu.