The RFid Reader Board is a kHz RF transmitter and reciever, featuring the EM controller chip. The reader has three main functions. The EM is replacement IC of the UB Atmel reader chip. EM is a CMOS integrated transceiver circuit for RFID applications. EM Read only Receiver and transmit to UART 10 digit hexa code by ASCII.
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RFID technology is an exciting technology. The EM chip allows us to create a reader with little code or processor resources. A complete KIT is available from the web shop at rifd.
As you can see from the data sheets, the EM needs little external hardware. A coil, capacitors that tune the coil for KHz, are basically all that you need. IC1 is a voltage regulator that regulates the input voltage to 5V.
The capacitors stabilize the output voltage. The micro mega88 has a small 32 KHz crystal so the soft clock can be used. There are 3 switches that can be used for menu input, and there is a relay that can be used to wm4095 a door opener. Parallel on the relay there is a LED for a visible indication. IC4 is a serial interface buffer so we can connect the PCB to our computer for logging and programming.
As usually we start with the components that have the lowest height. This to prevent damage to the active components IC. Em095 sure the chip is lined out right and that pin 1 matches the small dot on the chip which is an indication for pin 1. Then solder pin 1 and 16 so the chip can not be moved anymore. Now solder the remaining pins. Use an iron with a small tip. When you use too much solder, and two feet are soldered together do not panic.
Just finish soldering and when ready, use some copper braid to remove the solder between the 2 feet. This works best when you lay the braid over the 2 pins, then push the solder iron to the braid so it will heat up. Then after some seconds, add some solder which will get sucked into eem4095 braid. This will in turn suck the other solder into the braid. While it does not seem logical to add solder, it will conduct the heat better. But since the used SMD chip is relatively large there should not be any problem.
Now the PCB is ready. Make sure there are no solder drops on the PCB. You can measure with an Ohm-meter if there is a short circuit. Measure pin 1 and pin 2 of IC1 the voltage input and pin 3 and pin 2 of IC1 the voltage output.
EM4095 RFID FRONT END CHIP
You can connect the battery cord to header X1. The red wire is the plus. Since the circuit is not for beginners, there is no reverse polarity protection.
While the does not mind a short circuit, the C1 elco might not like it. Connect the battery and measure with a Volt meter if IC1 actual outputs 5V. If not, check the input voltage, and for a possible shortcut. Connect the antenna to connector X2. The PCB is now ready for use. Since the chip has a boot loader, you can serial program the device. We made a simple AN that can be used as a door opener. It has simple menu, and we can add new tags.
When a valid tag is held in front of the antenna, it will activate the relay for 2 seconds.
The LED will be em4059 on as well. Connect a serial cable to X6 and press F4 to program. Now the program will start and show some info on the LCD. Press S3, and then hold the TAG before the coil.
When there is roomor the tag is new, it will be stored.
Build loop PCB antenna for EM RFID Reader
Otherwise it will be ignored. To make the code more secure you could add a delay so that a valid tag must be received twice, so after the valid TAG, wait 1 second, and then start a new measurement and check e4m095 the TAG is valid again. This will prevent where a bit generator could be used to generate all possible codes. The other hack would be to listen with a long range KHz antenna, and recording all bits.
A long range scanner would be rfdi hard to make. It would be easier to open the door with a crowbar. When you open your door with this device, make sure you have a backup option like a key in case there is no power. Also, when the door is opened by a magnetic door opener, make sure it has the right quality for the entrance you want to protect. The oscillator frequency must be KHz. You can measure this with an oscilloscope. It is possible that you need to remove a few windings of the antenna coil to get an exact KHz.
This will result in a higher distance that you can use for the tags.
EM4095 rfid 125khz rfid reader module
Introduction RFID technology is an exciting technology. The data sheets you can download from: The black rfi must match the line on the PCB Kathode. The square pad matches the longest wire of the LED Anode. Notice the gap in the middle which must match with the PCB.
M3x6 bolt and nut.