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  1. #1

    Default Confused by Arraywrite

    I've looked at the examples and posts on here and they are helpful but.....

    OK I have a 38x25 display.
    I can talk to it using hserout and have a 1ms interrupt running so want to send it 1 character every ms.
    No problems so far. I can do that.

    I've modded the pb3 library (using the example post) to allow a 1000 element array to store my display data (38x25 = 950)
    Not sure i need to do this and might be better using a smaller array (38 elements) and line at a time... :?

    So some questions.. when i write to the array using array write what happens when it gets to the end? 1000th character is sent to it.
    Yes it exit's but how do you reset it and start filling it from the beginning?
    Does it reset every time you do an Array write?
    What happens to the overflowed characters?
    Do you have to manage the length to ensure the message you are sending so it will fit in?

    Some working examples might be useful if anyone has any? Thanks

  2. #2
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    Default Re: Confused by Arraywrite

    The ARRAYWRITE command prepends the LOOKUP or LOOKDOWN commands.

    Code:
    b0 VAR BYTE
    b1 VAR BYTE
    Letter VAR BYTE[9]
    ARRAYWRITE Letter, ["SOMETHING"]
    FOR b0 = 0 TO 8
     LOOKUP b0, [Letter], b1
     HSEROUT b1
    NEXT b0
    The ARRAYWRITE command loads what you want into a Table. In the code above, the ASCii "SOMETHING" is contained in the Table. The LOOKUP command pulls the ASCii letters from the Table one at a time and makes them available to the variable b1. If you wanted to send a dynamic value you could use:

    Code:
    Pot VAR BYTE
    b0 VAR BYTE
    b1 VAR BYTE
    Letter VAR BYTE[3]
    ADCIN 3,Pot
    ARRAYWRITE Letter, [#Pot]
    FOR b0 = 0 TO 2
     LOOKUP b0, [Letter], b1
     HSEROUT b1
    NEXT b0
    In the above code an ADC value is read from AN3 to Pot then turned to ASCii ([#Pot]). If the Pot value is 133, "ARRAYWRITE Letter, [#Pot]" will load the Array "Letter" with "1", "3", and "3". The code is abbreviated to get the idea across, not intended to be plug-n-play.

    As for a 1000 Byte Array, PIC pages are limited to 256 bytes. You'll probably have to create 4 separate Tables to accommodate all 1000 variables. Consider an Array that contains the alphabet and numeric characters, or whatever, or a subroutine that converts your desired output to display-compatible format.

  3. #3
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    Default Re: Confused by Arraywrite

    mikes quote here is very wrong

    As for a 1000 Byte Array, PIC pages are limited to 256 bytes. You'll probably have to create 4 separate Tables to accommodate all 1000 variables.
    from the manual

    Arrays must fit entirely within one RAM-bank on 12-bit and 14-bit devices (PIC10, PIC12, and PIC16). Arrays may span banks on PIC18 devices. On PIC18 devices, BYTE, WORD and LONG-sized arrays are only limited in length by the amount of available memory. The compiler will assure that arrays, as well as scalar variables, will fit in memory before successfully compiling.
    the inflexible way
    Code:
    ARRAYWRITE Letter, ["SOMETHING"]
    FOR b0 = 0 TO 8
     LOOKUP b0, [Letter], b1
     HSEROUT b1
    NEXT b0
    the flexible way , use null termination method

    Code:
    b0=0
    ARRAYWRITE Letter, ["SOMETHING",0]
    while letter[b0]
     LOOKUP b0, [Letter], b1
     b0=b0+1
    wend
    This is more entertaining than Free to Air TV

  4. #4
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    Default Re: Confused by Arraywrite

    Richard, have you actually tried your null termination method?
    When trying these lines of code :

    OUTARRAY VAR BYTE(80) 'serial string output array
    BYTEIN VAR BYTE
    character VAR BYTE

    BYTEIN = 0
    WHILE OUTARRAY(BYTEIN)
    LOOKUP BYTEIN,[OUTARRAY],CHARACTER
    ' TX_BYTES2(TX_OUTPUT2) = CHARACTER
    BYTEIN = BYTEIN + 1
    ' GOSUB SNDCHAR2 'INCREMENT BUFFER POINTERS
    WEND

    I get the error: Expected '['
    Dave Purola,
    N8NTA
    EN82fn

  5. #5
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    Default Re: Confused by Arraywrite

    have you actually tried your null termination method?
    not that example , the lookup line might need to be lookup2 , the lookup line is not really relevant to the null termination array processing method

    Code:
     OUTARRAY	VAR	BYTE(80)	'serial string output array
     BYTEIN		VAR	BYTE
     character		VAR	BYTE
    
    	BYTEIN = 0
    	WHILE OUTARRAY(BYTEIN)
    		LOOKUP2 BYTEIN,[OUTARRAY],CHARACTER
     '		TX_BYTES2(TX_OUTPUT2) = CHARACTER
    		BYTEIN = BYTEIN + 1
     '		GOSUB SNDCHAR2		'INCREMENT BUFFER POINTERS
    	WEND
    This is more entertaining than Free to Air TV

  6. #6
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    Default Re: Confused by Arraywrite

    Well Richard, Making the statement LOOKUP2 does not seem to work. I have no idea where the data is coming from but, it is not what I set the ARRAYWRITE statement with. The only thing that is correct as I can see it is the string length.
    Dave Purola,
    N8NTA
    EN82fn

  7. #7
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    Default Re: Confused by Arraywrite

    your correct dave , I have fallen into a trap set by mike, a sram array is not a valid source for any pbp lookup command . the concept seems flawed anyway surely the lookup table source should be the translated data table and the outarray data the index. we already have b0 as a pointer to the outarray data .
    my intent was just to demonstrate how to cycle through an array of variable length using a null as the end marker
    This is more entertaining than Free to Air TV

  8. #8
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    Default Re: Confused by Arraywrite

    Retypesnikrep, what are you wanting to display? Is there constants like "Temperature is " along with variables like "TempC VAR BYTE"? I've used the HD44780 based LCD for several projects. A display line would look like:

    Code:
    ARRAYWRITE LPsiA, [#LPsi]
        for b0 = 0 to 13
            LOOKUP b0,["Low PSI Set = "],b1
            PORTB = b1
            gosub Send
        next b0
        if LPsi < 10 then
            LPsiA[1] = LPsiA[0]
            LPsiA[0] = " "  
        endif 
        PORTB = LPsiA[0]
            gosub Send
        PORTB = LPsiA[1]
            gosub Send
    Here I use ARRAYWRITE to extract the individual digits of my pressure value LPsi into ARRAY LPsiA in ASCii format.

    I use LOOKUP to extract individual characters from the string "Low PSI Set = ".

  9. #9

    Default Re: Confused by Arraywrite

    basically I have a 1ms interrupt going on.

    I want this to check a buffer for stuff waiting to be sent to the screen, and if stuff waiting then send it via Hserout one chr at a time.

    OK so far.

    I want to fill my large buffer using array write as it contains text and variables... ie
    So it mimics the screen, as if I was writing it straight to the screen using hserout....

    arraywrite buffer, ["Temperature 1 is ",#Temp1,"C",32,"Temperature 1 is ",#Temp1,"C"]

  10. #10
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    Default Re: Confused by Arraywrite

    Thanks Richard, I do understand now. By the way, What's Mpgmike and Retepsniarep talking about? It seems as though this tread has been hijacked.
    Dave Purola,
    N8NTA
    EN82fn

  11. #11
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    Default Re: Confused by Arraywrite

    Richard, After chatting with Charles, I decided to eliminate the "lookup2" statement and just pass the array variable to the serial buffer routine. All is working now. Nice and neat. Here is the code:

    '************************************************* ********************
    SERIALOUT2: 'OUTPUT SERIAL STRING TO PORT 2
    '************************************************* ********************
    BYTEIN = 0
    WHILE OUTARRAY(BYTEIN)
    TX_BYTES2(TX_OUTPUT2) = OUTARRAY(BYTEIN)
    BYTEIN = BYTEIN + 1
    GOSUB SNDCHAR2 'INCREMENT BUFFER POINTERS
    WEND
    RETURN
    Dave Purola,
    N8NTA
    EN82fn

  12. #12
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    Default Re: Confused by Arraywrite

    I want to fill my large buffer using array write as it contains text and variables... ie
    So it mimics the screen, as if I was writing it straight to the screen using hserout....
    it sounds like a ring buffer may do what you need
    This is more entertaining than Free to Air TV

  13. #13
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    Default Re: Confused by Arraywrite

    here is a rx ring buffer example I worked on with someone on one of the pbp forums some years back.
    its limited to 256 bytes max buffer size.

    Code:
     INCLUDE "DT_INTS-18.bas"            
    'INCLUDE "ReEnterPBP-18.bas"         
    
    
    ASM                                 ; 
    INT_LIST  macro                     ; IntSource,   Label,    Type, ResetFlag?
            INT_Handler    RX1_INT,   myint,   ASM,    yes
        endm
        INT_CREATE                      ; Creates the interrupt processor
    ENDASM
    
    
       DEFINE DEBUG_REG PORTB
       DEFINE DEBUG_BIT 7
       DEFINE DEBUG_BAUD 9600
       DEFINE DEBUG_MODE 0
    
    TRISB.7=0  ;DEBUG
    LATB.7=1   ;DEBUG
    
    
    
    
    
    index_in         VAR BYTE bank0         ' Pointer - next empty location in buffer
    index_out        VAR BYTE bank0         ' Pointer - location of oldest character in buffer
    errflag          VAR BYTE bank0         ' Error flag
    UartFlag         VAR errflag.0
    BufferFlag       VAR errflag.1
     
    
     
    buffer_size      CON  256                               ' Sets the size of the ring buffer  
    buffer           VAR  BYTE[buffer_size]     ' Array variable for holding received characters  
     
    BufChar          VAR  BYTE          ' Stores the character retrieved from the buffer
    
    
    '    trisC.6=0    ;tx1
        RCSTA1 = $90   ' Enable serial port & continuous receive
    '   TXSTA1 = $24   ' Enable transmit, BRGH = 1
        SPBRG1 = 56    ' 38400 Baud @ 48MHz, -0.16%
        SPBRGH1 = 1
        BAUDCON1.3 = 1 ' Enable 16 bit baudrate generator
    
    
    
    
    
     GoTo start                       ' Skip around interrupt handler
    
    Asm
    myint
    ; Check for hardware overrun error
       btfsc   RCSTA1,OERR   ; Check for usart overrun
       bra    usart_err    ; jump to assembly error routine
    ; Test for buffer overrun               
       incf   _index_in,W   ; Increment index_in to W
       subwf  _index_out,W  ; Subtract indexes to test for buffer overrun
       btfsc  STATUS,Z      ; check for zero (index_in = index_out)
       bra   buffer_err    ; jump to error routine if zero
    ; Increment the index_in pointer and reset it if it's outside the ring buffer
       incf   _index_in,F   ; Increment index_in to index_in
       movf   _index_in,W   ; Move new index_in to W
       sublw  _buffer_size-1; Subtract index_in from buffer_size-1
       btfss  STATUS, C     ; If index_in => buffer_size
       clrf   _index_in     ; Clear index_in
    ; Set FSR with the location of the next empty location in buffer
       movlw   High _buffer  ;Store the High byte of buffer to FSR0H
       movwf   FSR0H
       movlw   Low _buffer  ; Get the Low byte of buffer[0]
       addwf   _index_in,W  ; Add index_in to point to next empty slot
       movwf   FSR0L        ; Store Low byte of pointer in FSR0
    ; Read and store the character from the USART           
       movf   RCREG1,W       ; Read the received character
       movwf  INDF0          ; Put the received character in FSR0 location
       BTFSC  PIR1,TX1IF      ;ANY MORE ?
       BRA    myint
       
    finished 
       RST?RP
       INT_RETURN
     
    ; Error routines        
    buffer_err              ; Jump here on buffer error
       bsf   _errflag,1     ; Set the buffer flag
    usart_err               ; Jump here on USART error
       bsf   _errflag,0     ; Set the USART flag
       movf  RCREG1, W       ; Trash the received character
       bra  finished       ; Restore state and return to program
    EndAsm
    
    
    
    
    
    
    
    
    start:
        PAUSE 3000                              ' Let ME CONNECT PICKIT UART MODULE
        Debug "Start",13 ,13
         
        index_in = 0                    ' Initialize ringbuffer variables
        index_out = 0  
        GOSUB error  ;CLR AND RESET EUART
        
    
    @   INT_ENABLE  RX_INT     ; Enable USART RX Interrupts  
    Main:
       DEBUG "Main", 13 ,13
    
    MainLoop:   
     
    display:              ' dump the buffer to the terminal
       IF errflag Then GOSUB error ' Goto error routine if needed
       IF index_in = index_out Then mainloop ' loop if nothing in buffer     
       GoSub getbuf         ' Get a character from buffer   
       debug bufchar        ' Send the character to terminal
       GoTo display         ' Check for more characters in buffer
    
    ' Get a character from the buffer
    getbuf:                                 ' Move the next character in buffer to bufchar
       intcon = 0                          ' Disable interrupts while reading buffer
       index_out = index_out + 1     ' Increment index_out pointer (0 to 63)
       IF index_out => buffer_size Then index_out = 0 ' Reset pointer if outside buffer
       bufchar = buffer[index_out]  ' Read buffer location(index_out)
       INTCON = %11000000           ' Enable interrupts
       Return
    
    ' Display an error
    error:                          ' Display error message
       INTCON = 0                   ' Disable interrupts while in the error routine
       IF errflag.1 Then            ' Determine the error
          debug "B!",13,13 ' Display buffer error on line-2
       Else
          debug "U!",13,13  ' Display usart error on line_2
       EndIF
       PIR1.4=0      
       errflag = 0          ' Reset the error flag
       RCSTA1.4=0           'CREN = 0 Disable continuous receive to clear hardware error
       RCSTA1.4=1           'CREN = 1 Enable continuous receive
       INTCON = %11000000   ' Enable interrupts
       GoTo RETURN         ' repeat
    
        ;clear any rcsta error
    This is more entertaining than Free to Air TV

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