WiFly ( RN-XV ) UART

Wireless & IoT
1

Hi,

I’ve been using my RN-XV for about a week now. I originally hooked it up and had it start in ADHOC

mode, I then used telnet to the device to have it assoc with my AP and was happy.

Today I wanted to connect to the boards UART ( pins 2 & 3 & gnd ) off the RN-XV. I connected a USB to Serial

cable to my laptop and connected to the RN-XV.

I used 9600 baud, no parity, 1 stop bit, no flow control.

It connects but I only get gibberish. I can see data being received by the terminal app, but I cannot

for the life of me get it to print readable characters. I’ve tried different settings as well as different

terminal apps …

I’m sure someone else has done this… The RN-XV is powered by battery. Works just fine via telnet

but not over the UART / serial. The reason this is a problem is that I want to send data from a sensor

that talks rs232 and expected to be able to connect the two, but I can’t seem to get basic comm going

using serial.

I’m using a UC232A ( http://www.aten.com/products/productIte … _no=UC232A ) with Win7.

I’ve tried putty (serial), teraterm pro and hyperserialport with same results. And yes, I can talk to other

devices using the above with the same settings 9600-8-N-1 …

I even updated to the latest f/w and did a factory reset with no luck…

Anyone using a usb-to-rs232 adapter to talk to your WiFly RN-XV ?

I will try a “real” rs-232 port, when I can… just hoping my uart isn’t defective.

2

RS232 inverts signals on the wire. How are you converting from RS232 to RN-XV levels? Might you perhaps need to (re)invert them?

3

You need a 3.3 volt “TTL” type of USB-serial converter, like this one https://www.sparkfun.com/products/9716

BE SURE to do the modification for 3.3 volt I/O (or buy an adapter that is already configured for 3.3 V I/O).

However, you may already have permanently damaged the WiFly, as the serial adapter you linked to provides RS232 voltage levels, somewhere in the vicinity of +/- 12 volts.

4

At first, I had only connected the “RX” line… I got what looked like data. I could see 30-40 chars come in, then stop then another 30-40… This is typical of what I would get over telnet, only I could not read the data.

I can see now that the signal levels are inverted, and most likely TTL vs rs-232. I have a MAX232 chip and will try that.

The chip will work at 3.3 and does the inversion as well as signal level matching.