[FXT009] baud rate and clock frequency problem


#1

Hello guys,
i am working on a project which will collect several sensors data and send them work station via fxt009. I am facing problem with communicating fxt009 with AVR micro controller (Atmega32). however fxt009 is working fine with the pc via usb cable. i also checked the output signal from my micro controller and its working fine. but fxt009 is not responding, i am using a 8MHz crystal for the clock frequency and making the baudrate 115200 as this the default rate of fxt009. do i need a higher crystal? or Do i need any other chip to communicate with fxt009 with the microcontroller? as right now i am directly connecting the tx, rx of the micro-controller to rxd and txd of the fxt009.
i will highly appreciate if any body help me on this.


#2

Hi,
How are you connecting the microcontroller and FXT009? Is it via UART?
Can you share the schematic diagram? if the connection is not proper, then there is a chance of communication failure.

-Alex


#3

Hello Alex,
I am connecting through 15-pin SUB-D serial interface connector. Attached is the schematic diagram of the connections.



#4

The FXT has a true RS232 interface; ie, with +/- 12V levels.
You should not connect this direct to a microcontroller - you must use an RS232 transceiver :exclamation:


#5

But in the datasheet of fxt009, its written input/output voltage is +/- 5v not “+/- 12v”. please see the attached.



#6

But you still shouldn’t be applying negative voltage to your microcontroller, and your microcontroller cannot generate the negative voltage.

Don’t add unnecessary areas of doubt & uncertainty; do it properly - use an RS232 Transceiver :exclamation:


#7

Can you please post the schematic that you are using practically for your circuit?
Also what are all your hardware components?
Can you please share your interface and its components?
Also what are the components and the program(if you are using internal clock of AVR) for your clock frequency?


#8

probably a bit late - as there has been no reply from the OP for nearly a month now …


#9

Can you share the schematic diagram? if the connection is not proper, then there is a chance of communication failure.


#10

probably a bit late - as there has been no reply from the OP for over two years now …