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[ceibawx]

Hi everyone. My question is.
when I send a bitstream at 19.2k in tx xbee chip802.15.4
the data is 000000FFFFFF000000FFFFFF000000......(repeat)
but from rx xbee , I received the data is 0000FFFF0000FFFF......(repeat)
XBEE Baud rate is 19.2k
so what's the reason?
Why is the rx data different from tx data?

[stevech]

instead of a bit stream, show us what was in the bytes you sent.
Also, beware of PC terminal program, if that's what you're using, as it may be in an ASCII text mode and you are trying to send 8 bit bytes. Also watch the XBee setup, ASCII mode, where XON, XOFF and other ASCII characters get special processing.

[ceibawx]

this is code to transmit 8 bytes data repeatly. And I can see the data from PIC is right on oscillatescope. But when it is input into TX xbee, data from RX xbee is not correct.

and I see its rx data in xbee X-CTU and serial communication port assistant. yes .the data is ascii, but I also can choose hex format. But I think oscillatescope is more clear to see the data wave. so I use oscillatescope.




code in pic to transmit data.

Code: Select all

list             p=16F877           ; list directive to define processor
#include         <p16f877.inc>      ; processor specific variable definitions


; '__CONFIG' directive is used to embed configuration data within .asm file.
; The labels following the directive are located in the respective .inc file.
; See respective data sheet for additional information on configuration word.

; __CONFIG _CP_OFF & _WDT_OFF & _BODEN_OFF & _PWRTE_ON & _HS_OSC
; & _WRT_OFF & _LVP_OFF & _CPD_OFF

;C0 IS CLOCK INPUT
;C1 IS BIT DATA INPUT
;***** VARIABLE DEFINITIONS

w_temp           EQU     0x7D       ; variable used for context saving
status_temp      EQU     0x7E       ; variable used for context saving
pclath_temp      EQU     0x7F       ; variable used for context saving
;TempCounter      EQU     0xBC
;BitCounter       EQU     0xBB       ; vairable address used for bit conter
ByteCounter   EQU     0xBD       ;address used for byte counter


;**********************************************************************
       ORG       0x000             ; processor reset vector
       goto      Main               ; go to beginning of program
;**********************************************************************
; isr code can go here or be located as a call subroutine elsewhere

       ORG       0x004             ; interrupt vector location
       movwf     w_temp             ; save off current W register contents
       movf      STATUS,w           ; move status register into W register
       movwf     status_temp        ; save off contents of STATUS register
       movf      PCLATH,w           ; move pclath register into w register
       movwf     pclath_temp        ; save off contents of PCLATH register

       movf      pclath_temp,w      ; retrieve copy of PCLATH register
       movwf     PCLATH             ; restore pre-isr PCLATH register contents
       movf      status_temp,w      ; retrieve copy of STATUS register
       movwf     STATUS             ; restore pre-isr STATUS register contents
       swapf     w_temp,f
       swapf     w_temp,w           ; restore pre-isr W register contents
       retfie                       ; return from interrupt

Main:
       banksel   TRISC
       bcf       TRISC,6            ;c6=0 as output
       bsf       TRISC,0            ;c0=1 as input
       bsf       TRISC,1            ;c1=1 as input
; UART module setup
       banksel   SPBRG
       movlw     15                 ; rs232 baud as 20k
       movwf     SPBRG              ; Enable SPBRG register Baud Rate

       banksel   TXSTA               ; Select memory bank for TXSTA SFR
            
       bcf       TXSTA,TX9             ; 8-bit transmission
       bsf       TXSTA,TXEN             ; Enable Transmission 
       bcf       TXSTA,SYNC             ; Asynchronous mode
       bsf       TXSTA,BRGH             ; High Baud Rate

       banksel   RCSTA
       bsf       RCSTA,SPEN         ; Enable Serial port
       bsf       RCSTA,CREN         ; Enable Receiver
; *******************save data in pic*******************************
SaveData
       bsf      STATUS,RP0             ;bank 1
       movlw    0xFF
       movwf    0xBF
       movlw    0x00
       movwf    0xC0
       movlw    0xFF
       movwf    0xC1
       movlw    0x00
       movwf    0xC2
       movlw    0xFF
       movwf    0xC3
       movlw    0x00
       movwf    0xC4
;*********************transmit data new ******************************
TransData:
       MOVLW     0xBF
       MOVWF     FSR                ; TO RAM
       MOVLW     0x06
       MOVWF     ByteCounter     ; ChannelCounter=6

GoOnTransData:
       banksel   PIR1
       btfss     PIR1,TXIF          ;TXIF=1, TXREG is empty,skip
       goto      GoOnTransData      ;wait for TXIF=1
      
       banksel   TXREG
       MOVF      INDF,0
       MOVWF     TXREG             ; Move the data to the transmit register
       INCF      FSR,1             ; INDF  address number moves next
       BSF       STATUS,RP0
       DECFSZ    ByteCounter,1  ; ChannelCounter-1
       goto      GoOnTransData     ; go on
       goto      TransData
;FinishData:
       ;goto      FinishData

       END
;*********************transmit data finish******************************

[stevech]

No doubt, you have a good rationale for using assembly language rather than C.

Sorry, I don't have the patience to pore over the asm code.

[ceibawx]

My question is the PIC output is correct,and I can see it. So I refer that the problem is in xbee chip. So I guess that maybe I didn't use it correctly.

[ceibawx]

Hi Stevech,

"watch the XBee setup, ASCII mode, where XON, XOFF and other ASCII characters get special processing" Can you explain it for me? Your help is really appreciated.


Xing

instead of a bit stream, show us what was in the bytes you sent.
Also, beware of PC terminal program, if that's what you're using, as it may be in an ASCII text mode and you are trying to send 8 bit bytes. Also watch the XBee setup, ASCII mode, where XON, XOFF and other ASCII characters get special processing.

[sylvie369]

Obvious question: have you tried it at a slower baudrate?

You're going at a fast rate, and while your receiver is getting data, those data aren't right. If it works properly when you slow it down, you narrow down considerably the possibilities for the source of the problem.

[ceibawx]

thanks. I will try.then tell you results.
another question. can you explain xbee communicate theory? When it transmit data, it also can receive data? so when it receives data, the data it wants to send will be stored in buffer temporary? Then it received data is finished, then it will continue sending data.

Obvious question: have you tried it at a slower baudrate?

You're going at a fast rate, and while your receiver is getting data, those data aren't right. If it works properly when you slow it down, you narrow down considerably the possibilities for the source of the problem.

[stevech]

thanks. I will try.then tell you results.
another question. can you explain xbee communicate theory? When it transmit data, it also can receive data? so when it receives data, the data it wants to send will be stored in buffer temporary? Then it received data is finished, then it will continue sending data.

Obvious question: have you tried it at a slower baudrate?

You're going at a fast rate, and while your receiver is getting data, those data aren't right. If it works properly when you slow it down, you narrow down considerably the possibilities for the source of the problem.

see 802.15.4
buffering: this is written about in Digi's technical manuals.
Buffering relies on flow control and that is also described by Digi: either XON/XOFF or CTS in hardware.

[ceibawx]

Finally I found some reasons.
Firmware should be 10CD. I downloaded it. Then it did work.
But now on pcb board, the RX XBEE doesn't talk to TX XBEE.
Any body can help me?