Trouble "catching" inbound XBee data with RX in a loop

Falcon

Hello all,
Working on my project in small steps, I have one XBee sending a byte of DS1307 temperature data to another successfully.

I'm now trying to insert that receiver code into the main project which is a 7-Slot (BS2Px) loop that includes the following steps:

receives13 inbound bytes
processes those bytes into SPRAM
sends all data to an LCD
and, depending on which bytes have changed,
sends updates to a PINK
sends commands to a V-Stamp voice module




I'm unable to receive the temperature data when all Slots are included in the loop.

I do successfully receive the temperature data if I execute the initialization and then go into a loop of just the Slot with the XBee receive code.

I'm sure I'm missing the inbound data from the XBee trabsmitter while the rest of the main unit loop is executing..

Questions: How can I better receive that inbound XBee data?

Should I increase the length of the time-out in the SERIN command?

Is it possible to have the receiver ackknowledge the inbound data before the loop continues to execute?



All suggestions are welcomed.

falcon

Mike Green

You have to use flow control in the SERIN statement. The problem that you're running into is that the xBee transmits data to the Stamp while the Stamp is busy doing something other than a SERIN. You'll need an extra I/O pin connected to the xBee's CTS output pin. The SERIN statement will make this extra I/O pin HIGH when it's ready to receive data and will leave it LOW when the SERIN finishes (and is no longer "listening"). The xBee will stop sending when CTS goes LOW and will buffer anything that comes in until CTS goes HIGH again. See page 409 of the Stamp Manual.

I may have CTS backwards in that it may be HIGH to stop sending and LOW to allow sending from the xBee. You'll have to check the Stamp and xBee documentation.

Falcon

Mike,
I appreciate your response.
Page 11 of the Getting Started with XBee Modules mentions CTS but, if I understand, it applies to the transmitting end.

I have RTS implemented in my code as follows.

I’m using the following initialization code which includes the ATD6 1 statement to activate RTS:

DEBUG CLS,"Configuring XBee...",CR
PAUSE 3000                      ' Guard time
SEROUT XBTx,XBBaud,["+++"]          ' Command Mode Sequence
PAUSE 2000                      ' Guard time
SEROUT XBTx,XBBaud,["ATGT 3,MY 0,D6 1",CR]    ' Set low guard time
SEROUT XBTX,XBBaud,["ATCN",CR]      ' Exit Command Mode

The following shows the pin assignments for the XBee :

XBRx            PIN     0                  ' XBee DOUT
XBTx            PIN     1                  ' XBee DIN
RTS             PIN     2                  ' XBee RTS

And this code is in the main loop:

main:
  SERIN XBRx\RTS,XBBaud,1500,UpdateTOut,[DataIn]  ' Wait for "A" with timout
    SELECT DataIn

      CASE "A"
        SERIN XBRx\RTS,XBBaud,500,UpdateTOut,[DEC TempIn]
        DEBUG CRSRXY, 15, 33, BIN TempIn.BIT7, CR      'Displays WindowA Condition
        tF = TempIn * 9 / 10 + 32
        DEBUG CRSRXY, 35, 33, DEC tF,CR ' show the result on the PC screen
        DEBUG CRSRXY, 39, 33, "F", CR ' show the result on the PC screen

Do you see any glaring mistakes in how this is written?

falcon

Mike Green

Sorry about the RTS / CTS confusion (see here). In any event, you're using output flow control on the SERIN statements. I don't see anything obviously wrong although I don't have the documentation on the xBee AT commands to check against. Is the xBee responding appropriately to the configuration commands?

Falcon

Mike Green wrote: »

Sorry about the RTS / CTS confusion (see here). In any event, you're using output flow control on the SERIN statements. I don't see anything obviously wrong although I don't have the documentation on the xBee AT commands to check against. Is the xBee responding appropriately to the configuration commands?

Yes.

If I run the initialization code, then create a loop that only contains the XBee receive code, I do receive the temperature data. So I know the actual Receive code works.

When I start including parts of the other 7 Slots, I no longer receive the data. I do have a number of GET and PUT statements . Do they slow down the execution enough to cause a problem?


What is the logic used to determine Timeout, and WAIT modifier time periods?

In the following XBee receiver code, what length of Timeout period should I use for the main SERIN statement, and what length of Timeout period should I use for the SERIN statements within the SELECT-CASE?

main:
  SERIN XBRx\RTS,XBBaud,1000,UpdateTOut,[DataIn]  ' Wait for "A" with timout
    SELECT DataIn

      CASE "A"
        SERIN XBRx\RTS,XBBaud,200,UpdateTOut,[DEC TempIn]
        DEBUG CRSRXY, 15, 33, BIN TempIn.BIT7, CR      'Displays WindowA Condition
        tF = TempIn * 9 / 10 + 32
        DEBUG CRSRXY, 35, 33, "   ",CR
        DEBUG CRSRXY, 35, 33, DEC tF,CR ' show the result on the PC screen
        DEBUG CRSRXY, 39, 33, "F", CR ' show the result on the PC screen

      CASE "B"

        SERIN XBRx\RTS,XBBaud,200,UpdateTOut,[DEC TempIn]
        DEBUG CRSRXY, 15, 34, BIN TempIn.BIT7, CR      'Displays WindowA Condition
        tF = TempIn * 9 / 10 + 32
        DEBUG CRSRXY, 35, 34, "   ",CR
        DEBUG CRSRXY, 35, 34, DEC tF,CR ' show the result on the PC screen
        DEBUG CRSRXY, 39, 34, "F", CR ' show the result on the PC screen


      CASE "C"

        SERIN XBRx\RTS,XBBaud,200,UpdateTOut,[DEC TempIn]
        DEBUG CRSRXY, 15, 35, BIN TempIn.BIT7, CR      'Displays WindowA Condition
        tF = TempIn * 9 / 10 + 32
        DEBUG CRSRXY, 35, 35, "   ",CR
        DEBUG CRSRXY, 35, 35, DEC tF,CR ' show the result on the PC screen
        DEBUG CRSRXY, 39, 35, "F", CR ' show the result on the PC screen

Within the 8-Slot main loop I have a hard-wired SERIN from a remote BS2P40 using RTS and the WAIT modifier. How should I set determine the proper length for the Timeout for that SERIN? Could the WAIT modifier here be holding things up too long?

falcon