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Problems Interfcing Xbee series2 with PIC18f4550

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burhanmz

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I am trying to transmit and receive data over serial communication 'wireless-ly' using 2 Xbee modules (Zigbee series 2 , Znet-2.5 ver. 2mW).
First i tried to do the loop back test which was successful.
>End A: I connected one Xbee on its usb explorer board with PC, picking it up on X-CTU software.
>End B: I step up the other on bread board, by applying power and ground to it and shorted the Dout and Din using a wire.
-Loop back successful

Now when i tried to involve a microcontroller (Pic18F4550) at End B which takes in data received from Dout and simple instructions put it back to transmit it to Din.

So that its still Loop back (for a single byte) From End A to End B - ucontroller - End B - End A

I sent byte at a time.. but i get junk to what i transmit from End A. Even though i transmit only a single byte from End A but i sometimes get 2 or 3 bytes in return.
And all junk (for example sending ASCII 'A' get back hex FF,FB,F4)

So changed End A to another mircontroller setup (basic connections as in picture) and connected 2 LED bars on End A to see what was sent and what i received.

On End B i added a LCD to see what it received.

I first connect both serial connections with wire to check if both programs were working .. and they are .. no problem when both end connected with wires directly to each other.

but when i connect Xbee on both controllers (on their serial port as in picture), nothing happened. no transmission at all.

End-A
Code: 
	list	 p=18f4550
	#include p18f4550.inc
	
	config FOSC=HS
;	config FOSCS=off
	config wdt=off
	config pwrt=on

;=====================================================
; constant definitions
;=====================================================
;=====================================================
; PIC register equates(in boot start from 0x7D0)
R1 EQU 0x7D1
R2 EQU 0x7D2
R3 EQU 0x7D3
R4 EQU 0x7D4
CNT EQU 0x7D5
TEMP1 EQU 0x7D6
TEMP2 EQU 0x7D7
D_CNT	EQU	0x7D8
;=====================================================
;=====================================================
; variables in PIC RAM
;=====================================================
;cblock 0x0c
;endc
;============================================================
; program
;============================================================
;============================================================
; program
;============================================================

	org 0x800 ; start at address
	goto MAIN

; Space for interrupt handler, change interupt address for other processor
	org 0x0808
MAIN	
	CALL	SETUP_DELAY
	MOVLW	0x0F
	MOVWF	ADCON1
	CLRF	TRISB
	CLRF	PORTB
	CLRF	TRISD
	CLRF	PORTD
	CALL	DELAY1s
	CALL	SERIAL_INIT

START_OVER
	CALL	SET_MSG
	MOVLW	D'13'
	MOVWF	CNT
	CLRF	TEMP1
	CLRF	TEMP2
REPEAT
	CALL	READ_MSG
	CALL	T_X
	CALL	SEND2PORTB
	CALL	DELAY1s
	CALL	R_X
	CALL	SEND2PORTD
	CALL	DELAY1s
	DECF	CNT,F
	BNZ		REPEAT
	BRA		START_OVER

ENDD	BRA		ENDD


SERIAL_INIT
	MOVLW B'00100000'
	MOVWF TXSTA
	MOVLW B'00010000'
	MOVWF RCSTA
	MOVLW B'00000000'
	MOVWF BAUDCON

	CLRF	TXREG
	CLRF	RCREG
	BCF		TRISC,TX
	BSF		TRISC,RX

	MOVLW	D'31'
	MOVWF	SPBRG	;set serial baud 31->9.6kbps

	BSF		RCSTA,SPEN	;start serial baud
	RETURN
	
SEND2PORTB
	MOVFF	TEMP1,PORTB
	RETURN

SEND2PORTD
	MOVFF	TEMP2,PORTD
	RETURN

;rx call-----------------
R_X
S1 	BTFSS	PIR1,RCIF
	BRA		S1
	MOVFF	RCREG,TEMP2
	RETURN


;tx call-----------------
T_X
S2 	BTFSS	PIR1,TXIF
	BRA	S2
	MOVFF	TEMP1,TXREG
	RETURN

SET_MSG
	CLRF	TABLAT
	MOVLW	high(MSG1)
	MOVWF	TBLPTRH
	MOVLW	low(MSG1)
	MOVWF	TBLPTRL
	RETURN

READ_MSG
	TBLRD*+
	MOVFF	TABLAT,TEMP1
	RETURN


SETUP_DELAY;------------to be called atleast once to make delays workable
	MOVLW	0x08
	MOVWF	T0CON	;Timer 0 ;16-bit; internal clock; no prescale
	RETURN


DELAY1s	
	MOVLW	D'100'
	MOVWF	D_CNT
D1s	CALL	DELAY10ms
	DECF	D_CNT,F
	BNZ		D1s
	RETURN

DELAY100ms	
	MOVLW	D'10'
	MOVWF	D_CNT
D100ms	CALL	DELAY10ms
	DECF	D_CNT,F
	BNZ		D100ms
	RETURN
		
DELAY10ms
	MOVLW		0x3C
	MOVWF		TMR0H
	MOVLW		0xB0
	MOVWF		TMR0L
	BCF			INTCON, TMR0IF
	BSF			T0CON,TMR0ON	;start timer
TM0A	BTFSS		INTCON, TMR0IF
	BRA			TM0A
	BSF			T0CON,TMR0ON
	RETURN

DELAY1ms
	MOVLW		0xEC
	MOVWF		TMR0H
	MOVLW		0x78
	MOVWF		TMR0L
	BCF			INTCON, TMR0IF
	BSF			T0CON,TMR0ON	;start timer
TM0B	BTFSS		INTCON, TMR0IF
	BRA			TM0B
	BSF			T0CON,TMR0ON
	RETURN

DELAY100us
	MOVLW		0xFE
	MOVWF		TMR0H
	MOVLW		0x0C
	MOVWF		TMR0L
	BCF			INTCON, TMR0IF
	BSF			T0CON,TMR0ON	;start timer
TM0C	BTFSS		INTCON, TMR0IF
	BRA			TM0C
	BSF			T0CON,TMR0ON
	RETURN

DELAY10us
	MOVLW		0xFF
	MOVWF		TMR0H
	MOVLW		0xCE
	MOVWF		TMR0L
	BCF			INTCON, TMR0IF
	BSF			T0CON,TMR0ON	;start timer
TM0D	BTFSS		INTCON, TMR0IF
	BRA			TM0D
	BSF			T0CON,TMR0ON
	RETURN

DELAY1us
	MOVLW		0xFF
	MOVWF		TMR0H
	MOVLW		0xFB
	MOVWF		TMR0L
	BCF			INTCON, TMR0IF
	BSF			T0CON,TMR0ON	;start timer
TM0E	BTFSS		INTCON, TMR0IF
	BRA			TM0E
	BSF			T0CON,TMR0ON
	RETURN

;messages------------------------
MSG1 DB 0xFF,0xFE,0xFC,0xF8,0xF0,0xE0,0xC0,0x80,"HELLO",0
;============================================================
	end ; END OF PROGRAM
;============================================================

End-B
Code: 
	list	 p=18f4550
	#include p18f4550.inc
	
	config FOSC=HS
;	config FOSCS=off
	config wdt=off
	config pwrt=on

;=====================================================
; constant definitions
;=====================================================
;=====================================================
; PIC register equates(in boot start from 0x7D0)
R1 EQU 0x7D1
R2 EQU 0x7D2
R3 EQU 0x7D3
R4 EQU 0x7D4
CNT EQU 0x7D5
TEMP EQU 0x7D6
D_CNT	EQU	0x7D7
;=====================================================
LCD_DATA EQU PORTD
LCD_CTRL EQU PORTB
RS EQU RB0
RW EQU RB1
EN EQU RB2
;=====================================================
; variables in PIC RAM
;=====================================================
;cblock 0x0c
;endc
;============================================================
; program
;============================================================
;============================================================
; program
;============================================================

	org 0x800 ; start at address
	goto MAIN

; Space for interrupt handler, change interupt address for other processor
	org 0x0808
MAIN	
	CALL	SETUP_DELAY
	MOVLW	0x0F
	MOVWF	ADCON1      ;---making portApins[0,1,2,3], portBpins[0,1,2,3,4] and portEpins[0,1,2] as digital I/Os
	CALL	SERIAL_INIT
	CALL	LCD_INIT
	CALL 	CLR_LCD
	CALL	CURSOR_SHFT

AGAIN
	MOVLW	D'15'
	MOVWF	CNT
	CLRF	TEMP
	CALL 	CLR_LCD
	CALL	CURSOR_SHFT
	MOVLW	0x80
	CALL	POS_CURSOR
REPEAT
	CALL	R_X
	CALL	DISPLAY_DATA
	CALL	DELAY1s
	CALL	T_X
	CALL	DELAY1s
	DECF	CNT,F
	BNZ		REPEAT
	BRA		AGAIN

ENDD	BRA		ENDD


SERIAL_INIT
	MOVLW B'00100000'
	MOVWF TXSTA
	MOVLW B'00010000'
	MOVWF RCSTA
	MOVLW B'00000000'
	MOVWF BAUDCON

	CLRF	TXREG
	CLRF	RCREG
	BCF		TRISC,TX
	BSF		TRISC,RX

	MOVLW	D'31'
	MOVWF	SPBRG	;set serial baud 31->9.6kbps

	BSF		RCSTA,SPEN	;start serial baud
	RETURN
	



;rx call-----------------
R_X
S1 	BTFSS	PIR1,RCIF
	BRA		S1
	MOVFF	RCREG,TEMP
	RETURN


;tx call-----------------
T_X
S2 	BTFSS	PIR1,TXIF
	BRA		S2
	MOVFF	TEMP,TXREG
	RETURN

LCD_INIT
	CLRF	TRISD
	CLRF	TRISB
	CLRF	PORTD
	CLRF	PORTB
	
	BCF		LCD_CTRL,EN
	CALL	DELAY1ms
	MOVLW	0x38
	CALL	COMNWRT
	CALL	DELAY1ms
	MOVLW	0x0E
	CALL	COMNWRT
	CALL	DELAY1ms
	RETURN

CLR_LCD
	MOVLW	0x01
	CALL	COMNWRT
	CALL	DELAY1ms
	RETURN

;shift cursor to right that is shift/increment cursor positon towards right (0x04 for left)
CURSOR_SHFT
	MOVLW	0x06
	CALL	COMNWRT
	CALL	DELAY1ms
	RETURN
	
;move cursor to specific position on specific line
;line 1 0x80 and position 81,82,83...93
;line 2 0xC0 and position C1,C2,C3...D3
POS_CURSOR
	CALL	COMNWRT
	CALL	DELAY1ms
	RETURN


;read from message character by character
SET_MSG
	CLRF	TABLAT
	MOVLW	high(MSG1)
	MOVWF	TBLPTRH
	MOVLW	low(MSG1)
	MOVWF	TBLPTRL
	RETURN


;send display data to LCD
DISPLAY_DATA
	CALL 	DATAWRT
	CALL	DELAY1ms
	RETURN

COMNWRT	
	MOVWF	LCD_DATA
	BCF		LCD_CTRL,RS
	BCF		LCD_CTRL,RW
	BSF		LCD_CTRL,EN
	CALL	DELAY1ms
	BCF		LCD_CTRL,EN
	RETURN

DATAWRT	
	MOVFF	TEMP,LCD_DATA
	BSF		LCD_CTRL,RS
	BCF		LCD_CTRL,RW
	BSF		LCD_CTRL,EN
	CALL	DELAY1ms
	BCF		LCD_CTRL,EN
	RETURN


SETUP_DELAY;------------to be called atleast once to make delays workable
	MOVLW	0x08
	MOVWF	T0CON	;Timer 0 ;16-bit; internal clock; no prescale
	RETURN


DELAY1s	
	MOVLW	D'100'
	MOVWF	D_CNT
D1s	CALL	DELAY10ms
	DECF	D_CNT,F
	BNZ		D1s
	RETURN

DELAY100ms	
	MOVLW	D'10'
	MOVWF	D_CNT
D100ms	CALL	DELAY10ms
	DECF	D_CNT,F
	BNZ		D100ms
	RETURN
		
DELAY10ms
	MOVLW		0x3C
	MOVWF		TMR0H
	MOVLW		0xB0
	MOVWF		TMR0L
	BCF			INTCON, TMR0IF
	BSF			T0CON,TMR0ON	;start timer
TM0A	BTFSS		INTCON, TMR0IF
	BRA			TM0A
	BSF			T0CON,TMR0ON
	RETURN

DELAY1ms
	MOVLW		0xEC
	MOVWF		TMR0H
	MOVLW		0x78
	MOVWF		TMR0L
	BCF			INTCON, TMR0IF
	BSF			T0CON,TMR0ON	;start timer
TM0B	BTFSS		INTCON, TMR0IF
	BRA			TM0B
	BSF			T0CON,TMR0ON
	RETURN

DELAY100us
	MOVLW		0xFE
	MOVWF		TMR0H
	MOVLW		0x0C
	MOVWF		TMR0L
	BCF			INTCON, TMR0IF
	BSF			T0CON,TMR0ON	;start timer
TM0C	BTFSS		INTCON, TMR0IF
	BRA			TM0C
	BSF			T0CON,TMR0ON
	RETURN

DELAY10us
	MOVLW		0xFF
	MOVWF		TMR0H
	MOVLW		0xCE
	MOVWF		TMR0L
	BCF			INTCON, TMR0IF
	BSF			T0CON,TMR0ON	;start timer
TM0D	BTFSS		INTCON, TMR0IF
	BRA			TM0D
	BSF			T0CON,TMR0ON
	RETURN

DELAY1us
	MOVLW		0xFF
	MOVWF		TMR0H
	MOVLW		0xFB
	MOVWF		TMR0L
	BCF			INTCON, TMR0IF
	BSF			T0CON,TMR0ON	;start timer
TM0E	BTFSS		INTCON, TMR0IF
	BRA			TM0E
	BSF			T0CON,TMR0ON
	RETURN

;============================================================
	end ; END OF PROGRAM
;============================================================

Can some one tell me what am i doing wrong. I have also attach the config pics of boht Xbee modules.
 

Attachments

  • basic connection.PNG
    basic connection.PNG
    11.8 KB · Views: 510
  • coordinator.PNG
    coordinator.PNG
    47.3 KB · Views: 331
  • end device.PNG
    end device.PNG
    32.6 KB · Views: 316
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