Hey guys!
I just finished my project on RFID Door lock . It uses ID-20 RFID Reader from Innovation that reads 125kHz RFID tags. The reading distance is up to 2 inches.
While browsing the datasheet, I saw a smaller version of the reader the ID-2 that needs an external antenna.
The questions are...
What are the parameters that I should consider in able to maximize the range of the reader?
Does larger coil means longer read range?
Good day!
I'm thinking about rfid door locks again 
Could you help me out on what to add to the arduino so I can have an rfid door lock that could read a card 5ft away? Is the ID-20 ideal for this type of application? I want to use passive cards as much as possible. Also, if I want the reader to have multiple card detection will I just change the code or should I buy a different reader?
Hello!
It's been a year and a month since I posted a topic about RFIDs --> Building antenna for ID-2 (RFID Reader) but nobody responded 
Anyway, my mom bought a car (Ford Ecosport) which have a keyless entry.
And I thought hmm... train of thought choo choo-ing
Long range means RFID not infrared.
But what range?
300-400Mhz.
Is it active?
yes, it has a battery.
How come the battery doesn't wear down? Is it charging when I plug the car key in the ignition?
(Her old car has a fob key and it has been my long assumption that the battery charges when she puts the key on the car ignition haha) duh, push button ignition.
What? Why? How does fob keys work really?
both the car and key has a transceiver. The battery is only needed when I push a button.
Why other cars doesn't open when I push a button? Does it have a code like RFID tags? but I saw a hack and they can copy the id and they can open the door lock but why are they saying fob is secure?
Says they use rolling codes.
What? Read it here: How Remote Entry Works
">The transmitter's controller chip has a memory location that holds the current 40-bit code. When you push a button on your key fob, it sends that 40-bit code along with a function code that tells the car what you want to do (lock the doors, unlock the doors, open the trunk, etc.).
>The receiver's controller chip also has a memory location that holds the current 40-bit code. If the receiver gets the 40-bit code it expects, then it performs the requested function. If not, it does nothing.
>Both the transmitter and the receiver use the same pseudo-random number generator. When the transmitter sends a 40-bit code, it uses the pseudo-random number generator to pick a new code, which it stores in memory. On the other end, when the receiver receives a valid code, it uses the same pseudo-random number generator to pick a new one. In this way, the transmitter and the receiver are synchronized. The receiver only opens the door if it receives the code it expects."
They both have a random number generator? How do they sync if they generate both random numbers? random is random, right?
train stopped here
then again I remembered one time when she was in a hurry to go to a meeting and left my sister to drive the car it alarmed saying the key is out of range or outside the vehicle. we had to call her to get the key.
Well that changed everything. It means the car checks if the key is inside the vehicle. And it can only do so if the key emits an ID. But fob key only transmits if a button is pushed. Wait. There are cars that open when the key is inside the car bubble. Is the key and the car constantly looking for each other then? Why doesn't the battery wear down easily again?
train stopped here again
Can anyone kindly explain how the rolling codes works? I have read it is based on the clock and the initial 40 bit code but I'm still confused. Does the key have a clock? Are random numbers not that random if I will base the generated number from the initial code and time? Or is it really the transmitter that sends the random number? the receiver only stores the value then uses it on the transmitters next command?
Also, how do the key searching works? is the key constantly emitting rf for the car to recognise? I can't see any reading on this.
It's been a year and a month since I posted a topic about RFIDs --> Building antenna for ID-2 (RFID Reader) but nobody responded
Don't bump.
Its against forum rules and will get your post removed.
Key fobs that have a push button use a small battery to power the Tx. As it only works for a short time, the battery lasts a long time. It is replaceable.
A rolling code uses a proprietary algorithm to synchronise the codes. The fob needs to be setup for the vehicle to recognise it. That is why there is a procedure to go through if you need to replace a lost key.
The key also has an RFID chip that is read by the car when it is in the ignition. This is why it is possible to have service keys that do not have a remote button. It also has to be setup to the vehicle.
Keyless entry uses a stronger RFID system that can pick up the fob from outside the vehicle.
Weedpharma
weedpharma:
A rolling code uses a proprietary algorithm to synchronise the codes. The fob needs to be setup for the vehicle to recognise it. That is why there is a procedure to go through if you need to replace a lost key.
But how do they synchronize? Who generates the random number?
weedpharma:
The key also has an RFID chip that is read by the car when it is in the ignition. This is why it is possible to have service keys that do not have a remote button. It also has to be setup to the vehicle.Keyless entry uses a stronger RFID system that can pick up the fob from outside the vehicle.
The car can only read the RFID chip if it is powered. They say fob only uses the battery when a button is pushed so how can the car read it if it is not powered up? If it uses magnetic induction (using an antenna to power up the card) What antenna does it use?
arduinoTime:
What are the parameters that I should consider in able to maximize the range of the reader?
Does larger coil means longer read range?
Larger diameter and more turns?
The design specs are in the user manual:
See the section titled: Designing Coils for ID2
They also recommend you reference this MicroChip document:
Matching Small Loop Antennas to rfPICtm Devices
When the key is made for a particular vehicle, the key is associated with the vehicle control computer. The car computer learns that the key is for that car. By some magical algorithm, the two then stay in synch.
The push button is only part of the key. It is used to unlock the door then is not used.
The RFID part is in the vehicle. It interrogates the chip embedded in the key in the same manner that pets are microchipped. The battery in the fob is not used. If you cut the head of the key, you can still turn the key, but as the vi hole is unable to read the ID in the head, the car will not run.
You cannot simply take your key and get another one cut then start the car.
Fully keyless vehicles simply have a larger range in the interrogator.
Weedpharma