rfid/nfc explained?

[izeman]

i'm thinking of using an nfc ring and combine it with my CA to "lock" it (maybe disable left or right button).
the question is: what do i need inside the CA to act as a switch? if i search for nfc on aliexpress i only find tags and stuff, but no receiver.
how common/cheap/small are they? and how easy to program/integrate inside the CA's case.
anyone got any experience?

https://www.aliexpress.com/item/Werable-devices-Jakcom-R3-Smart-Ring-electronic-CNC-Metal-Mini-Magic-Ring-with-IC-ID-NFC/32695373134.html?

 

[amberwolf]

a search by topic title for RFID will bring up at least three threads with different ways of doing it, including one by Alan B, another by Jeremy Harris, both of whom used normal means, and then mine about an idea to use the guts of an RFID doggie door...

 

[Alan B]

The RFID receivers I have worked with output a serial stream of the tag's ID number. They consist of a coil and a small pcboard. Adafruit and Sparkfun have products.

A small board like an Arduino is used to read the serial stream from the receiver board and determine if it is an allowed ID tag. That can be used to control power to the controller.

One tricky part is to power the RFID receiver only temporarily, if it is left powered it will drain the battery. They run on 5V so need a source for that.

 

[Sunder]

The problem with RFID and NFC, is that the range is extremely short (unless you use huge coils), because they both rely on induction. That is, one of the devices has no power of its own, and uses induction to get enough power to send the signal back. Think about RFID security tags, and NFC payment cards, and how close you need to be to trigger them. Do you want to be flying down a road, a car on your tail, and suddenly the bike switches off because you moved your hand? (Or even that there was some interference?)

You can use a bluetooth proximity switch, which has about a 3-5m range, and can be driven from your phone. So you just walk away from your bike and it switches off:

https://www.hackster.io/ifoundthemeaningoflife/ble-proximity-switch-f5df21

 

[Alan B]

Bluetooth is also risky, it is a very complex protocol and is subject to reconnection.

One technique is to use RFID or BT to enable the ignition system, but don't depend on a continuous signal. Once on, keep the bike on till it is turned off. Only require RFID or BT at the initial turn-on.

 

[nutnspecial]

Sounds like this is used to merely 'lock' the CA into it's current mode. There's prob a keyswitch for the bike/controller as well. For such a simple switch tapped into the CA control, could a hall sensor setup work and be easier than rfid? Just a tiny neo magnet as the key?

 

[izeman]

Sounds like this is used to merely 'lock' the CA into it's current mode. There's prob a keyswitch for the bike/controller as well. For such a simple switch tapped into the CA control, could a hall sensor setup work and be easier than rfid? Just a tiny neo magnet as the key?

that probably is the better solution, as shown in another CA related thread as well. put a reed switch inside the CA and a magnet will trigger it. remove the magnet and the CA is locked.
a nfc ring on your finger would be great as well. you need to touch the CA to press the buttons, so your in contact already.