This project is about connecting a RMD6300 RFID reader to the ESP8266 Wifi module in order to give access to doors and machinery.
To begin the RDM6300 is a great economical reader. Some other reader have the antenna built-in but this one is kind of clumsy connected to the board. However, this design allows the antenna to be installed in a better position inside a plastic box for example.
The RMD6300 has three group of pins. The antenna has to pins, the led driver has three (by the way, the led connects directly LED and 5V with no resistor, and it blinks a lot while the tag is near the antenna coil). The third group of pins have the TX and RX serial port. We just need the TX on pin 1.
The two modules run at different voltages. The RMD6300 reader runs at 5 volts and the WIFI module runs at 3.3 volts. Therefore, a step-down voltage regulator is used. The TX serial signal from the RMD6300 at 5V works fine with the ESP, no worries about it. Known as the ESP1 or the smallest ESP8266 module is also very economical, about 2-3 dollars.
The Arduino IDE is used to program the ESP that runs like a regular Arduino project. A Serial-USB converter is used to program and to listen to ESP serial signal. This converter is based on the company FTDI. Therefore, some people call it, the FTDI module. There are many with mini or micro USB connectors and the all have almost the same pinout. We just need plug the Ground and the RX pins. This converter needs a driver and there are for all operating systems found in the FTDI website here
We need to use the Arduino IDE to write the programs on the ESP module using the FTDI converter. Install the IDE from the arduino.cc site here. Then, on the preferences panel, you have to add on Additional Boards Manager URLs: "http://arduino.esp8266.com/stable/package_esp8266com_index.json".
Make sure you have selected the right port "USB-Serial converter" and there is a good speed.
We have to connect the ESP with the FTDI module using the following diagram. The interesting part part is that the GPIO0 (cero) pin in connected to ground, and CH_PD pin is to VCC. The FTDI module has to be 3.3V, do not use 5V or you might burn the ESP module. The FTDI can power the ESP to program only, but it does not give enough power to operate the WIFI feature correctly. Open the program file and press the Upload button to install the firmware or sketchbook into the ESP.
Once the program has been installed, disconnect the ESP from the FTDI and connect it using this following esquema: