Uart pic

edofbrighton · Jan 5, 2011

hi, i want to use the UART on the PIC16F690. TO START i just want to send some data from its TX pin to the RX PIN, so i can understand how it works. The code below is meant to send it recieve it and display it. The display works fine i just can recieve/transmitt data. can anyone point me in the right direction.

Code:

; DELAY EQUATES
CNT           EQU 0X25         ;ADDRESS FOR COUNTER
CNT2          EQU 0X26         ;ADDRESS FOR COUNTER2
CNT3          EQU 0X27         ;ADDRESS FOR COUNTER3
CNT4          EQU 0X28         ;ADDRESS FOR COUNTER4
; LCD EQUATES AND DEFINES
#DEFINE     DDRE   TRISB,7     ;DATA DIRECTION
#DEFINE     DDRRS  TRISB,4     ;DATA DIRECTION
#DEFINE     E      PORTA,2     ;ENABLE LINE ON LCD
#DEFINE     RS     PORTB,4     ;INSTRUCTION/DATA SELECT
#DEFINE 	RW	   PORTB,6
TEMP_LCD    EQU 0X3A           ;STORAGE FOR LCD
LCD         EQU PORTC          ;LCD DATA PORT
CLRSCR      EQU B'00000001'    ;COMMAND FOR CLRSCR
HOME        EQU B'00000010'    ;SENDS CURSOR TO HOME
ON          EQU B'00001100'    ;TURNS ON THE DISPLAY
OFF         EQU B'00001000'    ;TURNS THE DISPLAY OFF
LEFT        EQU B'00011000'    ;LEFT SHIFT
RIGHT       EQU B'00011100'    ;RIGHT SHIFT
LIN2        EQU B'11000000'    ;SETS TO LINE 2



;----------------------------------------
	; VECTOR FOR NORMAL START UP.
        ORG     0
        GOTO    START

; MAIN PROGRAM STARTS HERE:
START   CLRW			; CLEAR W.	
        MOVWF   PORTA           ; ENSURE PORTA IS ZERO BEFORE WE ENABLE IT.
        MOVWF   PORTB           ; ENSURE PORTB IS ZERO BEFORE WE ENABLE IT.
		movwf 	PORTC
		BSF     STATUS,RP1
		movlw	H'00'
		movwf 	ANSEL
		movwf 	ANSELH
		BCF     STATUS,RP0
        BSF     STATUS,RP0      ; SELECT BANK 1
        MOVLW   H'00'           ; MASK FOR PORTA FOR ALL OUTPUTS.
        MOVWF   TRISA           ; SET TRISA REGISTER.
        MOVLW   H'00'           ; MASK FOR PORTB FOR ALL OUTPUTS.
        MOVWF   TRISB           ; SET TRISB REGISTER.
		MOVLW	H'00'
		MOVwf	TRISC
        BCF     STATUS,RP0      ; RESELECT BANK 0.
        
        CALL	INIT_LCD	; Initialse the LCD
		bsf 	PORTA,2
        MOVLW   CLRSCR		; Clear the screen
        CALL    COMMAND		; Initiate the command in the W reg
		
        MOVLW   'H'		; send h
        CALL    DISPLAY		; Display the w reg on the LCD .;kv 
	
		MOVLW   CLRSCR		; Clear the screen
        CALL    COMMAND		; Initiate the command in the W reg
		MOVLW	'H'
		CALL 	send
		clrw

		MOVLW	H'FF'
		MOVWF	CNT3
COUNT3: MOVLW	0xff
		CALL 	DELAY
		DECFSZ CNT3,1
		GOTO COUNT3
			
		CALL	receive
		call 	DISPLAY



	goto		$	; Stop here	
	
	
	
;**************************lcdv6******************************
;Porta 1 for the enable and porta 2 for rs/ portb for lcd data
;*************************************************************
;************************************************************
; Initialize the LCD 
;************************************************************
INIT_LCD:
movlw .120
CALL	SEC_DELAY	           ; '' ''
MOVLW B'00110000'                  ;tell display its two lines
CALL COMMAND                       ;output to the screen
movlw .40
CALL SEC_DELAY
MOVLW B'00110000'
CALL COMMAND
MOVLW .100
CALL MDELAY
MOVLW B'00110000'
CALL COMMAND
MOVLW .100
CALL MDELAY
MOVLW B'00111100'					;FUNCTION SET
CALL COMMAND


MOVLW ON                           ;turn on display
CALL COMMAND                       ;output to the screen
MOVLW 0X01
CALL COMMAND
MOVLW B'00000110'                  ;shift along every write
CALL COMMAND                       ;output to the screen
RETURN
;************************************************************
; This routine is to set the lcd to the second line 
;************************************************************
SECOND_LINE:
MOVLW LIN2                     ;set to line 2
CALL COMMAND                   ;output to the screen
RETURN
;************************************************************
; THis executes a command in the W reg
;************************************************************
COMMAND:
BCF RS  
BCF	RW                       ;command coming
MOVWF LCD                      ;PUT OUT ONTO PORT
MOVLW .200                     ;delay time in microsecs
CALL MDELAY                    ;wait a while
MOVLW .250                     ;delay time in microsecs
CALL MDELAY                    ;WAIT
BSF E                          ;make sure the enable line is up 
MOVLW .200                     ;delay time
CALL MDELAY                    ;wait a while
MOVLW .250                     ;delay time in microsecs
CALL MDELAY                    ;WAIT
BCF E                          ;clock the data in
MOVLW .200                     ;delay time
CALL MDELAY                    ;wait a while
MOVLW .250                     ;delay time in microsecs
CALL MDELAY                    ;WAIT
BSF RS                         ;return to a data input
RETURN
;************************************************************
; This controls the module. When you call this 
; routine, the contents of the 'w' register is 
; displayed on the LCD screen. It is written in a 
; module like this for portability!! 
;************************************************************
DISPLAY:
BSF RS     
BCF	RW                    ;make sure it will accept data
MOVWF LCD                      ;send data to lcd
MOVLW .250                     ;delay time in microsecs
CALL MDELAY                    ;WAIT
MOVLW .250                     ;delay time in microsecs
CALL MDELAY                    ;WAIT
BSF E                          ;make sure the enable line is up 
MOVLW .250                     ;delay time
CALL MDELAY                    ;wait a while
MOVLW .250                     ;delay time in microsecs
CALL MDELAY                    ;WAIT
BCF E                          ;clock the data in
MOVLW .250                     ;delay time
CALL MDELAY                    ;wait a while
MOVLW .250                     ;delay time in microsecs
CALL MDELAY                    ;WAIT
RETURN


	
	
;*************************************************************
; 1 MICROSECOND DELAY 
;*************************************************************
MDELAY:
MOVWF CNT          ;LOAD DELAY TIME
COUNT:
NOP         ;TWO NO OPERATIONS
NOP                ;TO OBTAIN THE DELAY
DECFSZ CNT,1       ;DECREMENT THE COUNTER
GOTO COUNT         ;GOTO COUNT IF NOT FINISHED
RETURN


;*************************************************************
; quarter us delay 
;*************************************************************
DELAY:
MOVWF	CNT2
COUNT2: MOVLW	0xff
		CALL MDELAY
		DECFSZ CNT2,1
		GOTO COUNT2
RETURN

; ------------------------------------ 
; SET BAUD RATE TO COMMUNICATE WITH PC 
; ------------------------------------ 
; Boot Baud Rate = 9600, No Parity, 1 Stop Bit 
; 
UART_SET_UP:
        movlw 0x19              ; 0x19=9600 bps (0x0C=19200 bps) 
        movwf SPBRG 
        movlw b'00100100'       ; brgh = high (2) 
        movwf TXSTA             ; enable Async Transmission, set brgh 

        bcf STATUS,RP0          ; RAM PAGE 0 

        movlw b'10010000'       ; enable Async Reception 
        movwf RCSTA 
	    return 

; 
; ------------------------------------------- 
; RECEIVE CHARACTER FROM RS232 AND STORE IN W 
; ------------------------------------------- 
; This routine does not return until a character is received. 
; 
receive btfss PIR1,RCIF         ; (5) check for received data 
        goto receive 

        movf RCREG,W            ; save received data in W 
        return 
; 
; ------------------------------------------------------------- 
; SEND CHARACTER IN W VIA RS232 AND WAIT UNTIL FINISHED SENDING 
; ------------------------------------------------------------- 
; 
send    movwf TXREG             ; send data in W 

TransWt bsf STATUS,RP0          ; RAM PAGE 1 
WtHere  btfss TXSTA,TRMT        ; (1) transmission is complete if hi 
        goto WtHere 

        bcf STATUS,RP0          ; RAM PAGE 0 
        return 
		end

be80be · Jan 5, 2011

In order to configure pins RB6/SCK/SCL and
RB7/TX/CK as the Universal Synchronous
Asynchronous Receiver Transmitter:
• SPEN (RCSTA<7>) bit must be set (= 1),
• TRISB<6> bit must be set (= 1), and
• TRISB<7> bit must be set (= 1).
The operation of the EUSART module is controlled
through three registers:
• Transmit Status and Control (TXSTA)
• Receive Status and Control (RCSTA)
• Baud Rate Control (BAUDCTL)
• Baud Rate registers (SPBRGH:SPBRG)
See Registers 12-1, 12-2 and 12-3 for more detail.

I think you missed that part

ericgibbs · Jan 6, 2011

hi Ed,
Number of errors.
You call a SEC_DELAY which dosnt exist.
You never call UART_SET_UP

You dont specify a crystal freq, so I cannot be sure of your delays.

Sort these out and repost.

SPDCHK · Jan 6, 2011

I recognize some of that code. (I had to debug the very same code to test my USART application)

ericgibbs · Jan 6, 2011

hi Ed,
Look at this modified version of your program, it runs in Oshonsoft.
ie: TXD out, RXD in
The UART sub and TXD sub's have been changed.

The delays need working on.

be80be · Jan 6, 2011

Eric It's like digging threw a box of parts you never know want you'll find. Then you have them canned .inc file for the compiler. I don't see how the code ever compiled But they say it did. You need Oshonsoft 101, C18 101. Hi-tech c 101, etc LOL

ericgibbs · Jan 6, 2011

be80be said:
Eric It's like digging threw a box of parts you never know want you'll find. Then you have them canned .inc file for the compiler. I don't see how the code ever compiled But they say it did. You need Oshonsoft 101, C18 101. Hi-tech c 101, etc LOL

hi Burt,
As you say, been there, done that...

I am using some OP's program codes to check out the latest upgraded version of the Oshonsoft IDE Simulator.

edofbrighton · Jan 6, 2011

Sorry i didn't mean to post that bit of code, was very tiered last night. This is the edited code. It seems to get stuck in the receive sub-routine, probably because no byte is ever recieved. I have ommitted the LCD code because that runs fine.
I can't think what could be going wrong i stole this code from a text book. Eric i'm sorry i wanted to see the link you sent but i don't have the software.

Code:

 ORG     0
        GOTO    START

; MAIN PROGRAM STARTS HERE:
START   CLRW			; CLEAR W.	
        MOVWF   PORTA           ; ENSURE PORTA IS ZERO BEFORE WE ENABLE IT.
        MOVWF   PORTB           ; ENSURE PORTB IS ZERO BEFORE WE ENABLE IT.
		movwf 	PORTC
		BSF     STATUS,RP1
		movlw	H'00'
		movwf 	ANSEL
		movwf 	ANSELH
		BCF     STATUS,RP0
        BSF     STATUS,RP0      ; SELECT BANK 1
        MOVLW   H'00'           ; MASK FOR PORTA FOR ALL OUTPUTS.
        MOVWF   TRISA           ; SET TRISA REGISTER.
        MOVLW   B'00100000'           ; MASK FOR PORTB FOR ALL OUTPUTS.
        MOVWF   TRISB           ; SET TRISB REGISTER.
		MOVLW	H'00'
		MOVwf	TRISC
        BCF     STATUS,RP0      ; RESELECT BANK 0.


        CALL	INIT_LCD	; Initialse the LCD
        MOVLW   CLRSCR		; Clear the screen
        CALL    COMMAND		; Initiate the command in the W reg
	
		
		CALL 	UART_SETUP
	

	
		MOVLW	'H'
		CALL 	SEND
	
		
		CALL	RECEIVE
		MOVLW	'H'
		CALL	DISPLAY
	
       
	

		
   
		
       

		goto		$	; Stop here	

; ------------------------------------------- 
; RECEIVE CHARACTER FROM RS232 AND STORE IN W 
; ------------------------------------------- 
; This routine does not return until a character is received. 
; 
RECEIVE btfss PIR1,RCIF         ; (5) check for received data 
        goto RECEIVE 

        movf w           ; save received data in W 
        return 
; 
; ------------------------------------------------------------- 
; SEND CHARACTER IN W VIA RS232 AND WAIT UNTIL FINISHED SENDING 
; ------------------------------------------------------------- 
; 
SEND    BCF PIR1,RCIF
		movwf TXREG             ; send data in W 
;WtHere  btfss TXSTA,TRMT        ; (1) transmission is complete if hi 
;       goto WtHere 
        return 	
	
UART_SETUP:
        movlw 0x19              ; 0x19=9600 bps (0x0C=19200 bps) 
		bsf	STATUS,RP0
        movwf SPBRG 
        movlw b'00100100'       ; brgh = high (2) 
        movwf TXSTA             ; enable Async Transmission, set brgh 

        bcf STATUS,RP0          ; RAM PAGE 0 

        movlw b'10010000'       ; enable Async Reception 
        movwf RCSTA 
	    return

edofbrighton · Jan 6, 2011

Also if i uncomment the code in the send subroutine TMRT never goes high the PIC gets stuck there. any suggestions?

edofbrighton · Jan 6, 2011

got it working! the baud rate was too high i think. thank you for your help.

Uart pic

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