XBee Received Data Is Not Transfering to BS2.

tombutler

Set up: Propeller Activity Board control node running C to the main XBee (MXBee) module. The remote node is an XBee (RXBee) interfaced with BS2 Stamp running PBasic. I am using XCTU connected to the remote XBee (RXBee) USB adapter board. ( Propeller -> MXBee ~~~~~>RXBee ->BS2)

The control node sends a character via XBee to the remote node. Problem - The remote node STAMP does not receive or display the received character. I do know that the remote XBee is receiving the control nodes character as seen on XCTU. No display on the STAMP terminal. If I type a character in the XCTU console it is displayed on the STAMP console as planned. Based on the above I believe the Software on the Propeller and Stamp is okay.

Both XBee's are in the pass through mode (not API). I am self-learning this technology but I need some help figuring this out.

Thanks,

Tom

Mike Green

How do you have the remote XBee connected to the Stamp? Please show the Stamp program. I wonder if somehow the remote XBee is configured to use flow control and the Stamp is not supplying it. In that case, the XBee will buffer any incoming characters and not transmit to the Stamp. Often you want to use flow control so the Stamp won't miss any incoming characters, but your SERIN statement has to provide a pin for the flow control signal and that pin has to be wired to the XBee.

Mike Green

So here's what you sent me as a PM:

'
Initial XBee Stamp Transmit

' {$STAMP BS2}
' {$PBASIC 2.5}

'
Constants & Assignments
baud CON 84

rx PIN 15
tx PIN 14
rts PIN 11

DataIn VAR Byte

'
Main Program

DEBUG "Program Start", CR
PAUSE 500

GOSUB init

DEBUG "Awaiting Data...", CR

PAUSE 500

DO
SERIN rx, baud,[DataIn]
DEBUG "Data Received is ", DataIn,CR
SEROUT tx,baud,[DataIn]
LOOP

init:
PAUSE 500
DEBUG CR,CR,"Configuring XBee...",CR
PAUSE 200 ' Guard Time
SEROUT Tx,Baud,["+++"] ' Command Mode sequence
PAUSE 200 ' Guard Time
SEROUT tx,baud,["ATD6 1,CN",CR] ' RTS enable (D6 1) Exit Command Mode (CN)
PAUSE 100
SEROUT tx,baud, ["Main Node Initialized"]
RETURN


END

In your initialization, you enable RTS (Request To Send). That's the flow control I mentioned earlier and you've defined rts as I/O pin 11 which I assume you've connected to the XBee module's RTS pin. Your SERIN statement doesn't use flow control:

SERIN rx, baud,[DataIn]

You should add flow control as follows (see the Reference Manual's description for details):

SERIN rx\rts, baud,[DataIn]

tombutler

Thanks but I already tried that. Made really no difference. Still receive data from main node via xbee and displayed on remote xbee XCTU console. Does not get sent to STAMP. But if I type data on XCTU console stamp displays correctly.

Mike Green

You might give a call to Parallax Tech Support. I also suggest that you make up a block diagram of your setup under different circumstances or at least a clearer description and post that. I'm still a little confused about what happens when.

tombutler

I called Parallax first and they suggested to try here.

Block diagram of the system is attached along with a screen shot and code for both the main and remote processors. Thanks again for your help

Mike Green

As far as I can tell, you've got the USB Rx and the Stamp's Rx in parallel with the XBee's Tx and the USB Tx and Stamp's Tx in parallel with the XBee's Rx. The two Tx lines may fight each other. The RTS lines from the USB and Stamp are also in parallel feeding the XBee's RTS input. The XBee could theoretically send to both USB and the Stamp if the timing works out right, but you're courting damage to the paralleled outputs.

tombutler

OK got it to work by unplugging the USB connection to the XBee adapter. That may be what you were saying above. Anyway I guess I got to smart for my own good by trying to follow the comms flow.

Thanks again for your help.