next topic »

[on:]

I just purchased an active RFID RF8315R, and want to interface it with arduino uno. The RFID reciever has a serial female connector and in the specifications it is mentioned that its a plug and play and will transmit continuesly the rfid code. Well i cannot figure out how i can read serial data from the RFID reciever using UNO and then transmit it to the PC and view the data on the Serial Monitor. How can i hook up the Tx from the reciever to the RX of UNO, isnt the RX of UNO reserved for the serial communications with the PC? Help Please

[Reply #1 on:]

The RFID reciever has a serial female connector

Which almost certainly means that the output is RS232 (+/-12 V and inverted from TTL levels).

Well i cannot figure out how i can read serial data from the RFID reciever using UNO and then transmit it to the PC and view the data on the Serial Monitor. How can i hook up the Tx from the reciever to the RX of UNO, isnt the RX of UNO reserved for the serial communications with the PC?

How have you connected the device to the Arduino?

When you get your new Arduino and a MAX232 chip (to convert RS232 to TTL that the Arduino can use), we can help you hook everything together correctly.

[Reply #2 on:]

Hello, i aready bought the max 232 chip and ready to solve this problem. I tried however connecting the RFID reciever to the pc directly, i used a serial cable and hyper terminal, it works great but when i directly connect it to the arduino uno RX pin nothing.

[Reply #3 on:]

but when i directly connect it to the arduino uno RX pin nothing.

Where in the Arduino documentation does it say that it is safe to connect a 12V supply to the Arduino? Where does it say that it is safe to connect -12V to the Arduino?

When you are connecting the RFID reader directly to the Arduino, that is what you are doing. It is NOT safe.

Not to mention which -12V means HIGH and 12V means LOW. The Arduino expects 0V to mean LOW and 5V to mean HIGH.

[Reply #4 on:]

The RFID device which i am using is a small PCB with a 8 pin pic microcontroller on it, the board is powered by a 9v supply and i think there is a voltage regulator which brings it down to 5V (That i check on the power pins of the PIC microcontroller) here is the link to an image of that device [http://www.ebay.com/itm/RF8315R-Active-RFID-Receiver-Module-/300033606407]

[Reply #5 on:]

The 9 pin serial connector on that device is meant to connect directly to a PC's serial port, which expects RS232 voltage levels (-12V/+12V). Keep connecting that directly to your Arduino and you WILL fry it.

[Reply #6 on:]

i now built a max232 circuit, now i am receiving something but its just some unwanted character, and not what i am expecting. The baud rate is fine 9600 on every thing (rfid device and uno). My rfid has 2 transmitters and the receiver outputs codes of the transmitters via serial port and should be something like sh001 or sh007 but i am getting only one character for both which is "!". I rebuilt the max232 circuit and now i am getting the same problem but the character is different its "à". I am really annoyed by this small problem to which i have no solution... please help

the chip on the rfid is running on 5v how can 12v come in this picture, what can i do then to fix this problem?

[Reply #7 on:]

i now built a max232 circuit

How? A diagram would be useful. How is the RFID connected to the circuit? How is the circuit connected to the Arduino?

I am really annoyed by this small problem to which i have no solution... please help

Where is your code?

[Reply #8 on:]

It now works just fine, the RFID receiver has a pic micro controller and the manufacturers of the rfid receiver built a small circuit instead of using a rs232. I simply bypassed the circuit and connected the arduino's rx to tx pin of the pic controller. many thanks