Hi Wilfredo,
Are you sure you are swapping Rx and Tx? Ik looks more like Rx (third line from the SD-card side on the BBB) and gnd (6th line from the SD-card) As long as you are not typing anything, the Tx from your windows box stays low, and acts as a ground and the dataflow from the BBB works. As soon as you start typing something the gnd on the BBB will go high and low (from the Tx line from the windows box) resulting in unreadable data on the Rx-side
PS, On my BBB connecting Rx to Rx results in no received data, so there must be something else going on.(oh I did not connect Tx to Tx. I don’t like connecting 2 outputs together!)
LP
My serial debug works fine. I was just swapping the lines to show that it is possible to get an output with them crossed. I swapped pins 4 and 5 on the bbb side. Some times it sends data fine and other times I get that chicken noodle soup that I attached on my last post. But I always get some sort of output wether its readable or not. Oh and I had both lines connected at the same time. How are you getting any feedback or able to send commands with only one line connected?
-Wil
In my case, I use an FTDI board from sparkfun, this one: https://www.sparkfun.com/products/9873. The pin configuration matches with BBB and it works all the time.
I broke out the board and connected it with jumper wires pin 1 4 and 5. It still works, no surprise here. pull pin 5, no more received data, pull pin 4, no more transmitted data, connect wire 5 to pin 4 (BBB) no more connection either way. as I said, don’t like to connect wire 4 to pin 5, as both are outputs. All of this is exactly as it should be.
sometimes after plugging in the interface on a running BBB my terminal program (minicom) has trouble re-syncing the frame, i.e. the stopbit-startbit doesn’t get recognized. this happens with a one startbit, one stopbit configuration sometimes.
Nevertheless the basics stay the same, the BBB J1 has only one (data or otherwise) output and that is pin 5, B_UART0_TX. my FTDI has only one data input, socket 5, Rx. If those two don’t line up, Rx data is simply not possible.
I can only imagine that your interface has some smart self sensing gizmo that figures out by itself what the sending pin is, but then again that seems useless if it can’t determine the receiving pin. Or maybe it is using some half-duplex mode. Puzzeling…
LP
I am using the USB to xbee adapter from parallax. Not sure about auto sensing pins, just has ftdi chip and power regulator.
-Wil
This board has exactly the same schematics layout as mine. Same chip, same wiring. I don’t have a separate voltage converter, but you are not using it anyway in this setup. The 3v3 IO voltage (VCCIO) is generated on the FTDI chip, just like mine
I see where the confusion about the Rx Tx swap comes from though… The parallax board indicates Rx as DOUT and Tx as DIN. these are the XBee bus names, not the serial board functions.
Remains why you can receive data with it when the Rx Tx wires are crossed, I have no idea.
LP
I have no idea why it does either. But I know it works great when hooked up right. I just got done recovering a TL-mr3040 this morning that I installed pirate box on and it killed my network.
-Wil
Hey LP,
I feel like we hijacked this thread. Maybe I’ll check with Gerald and see if we can start a thread on random thoughts and discussions to try and keep the rest of the threads on track.
To the OP I apologize, and please let us know wether you got it sorted or not so we can try to get you squared away.
-Wil
I think another thread would make sense.
Gerald