Problems with I2CWRITE and the SAA1064 Seven-Segment Controller


Closed Thread
Results 1 to 4 of 4
  1. #1
    Join Date
    Jun 2011
    Location
    St. Louis, MO
    Posts
    13

    Default Problems with I2CWRITE and the SAA1064 Seven-Segment Controller

    I recently recieved a 4-digit seven-segment module that is controlled via I2C. The display has (4) seven-segment displays controlled by the SAA1064 4-digit LED-driver. The module has 4 pins, VCC, SDA, SCL, and GND. The display address is 0x70, which was selected by tieing the ADR pin of the SAA1064 to GND (This was already done on the module itself). I am new to using I2C devices and the corresponding commands in PICBASIC confuse me a bit. The SDA and SCL are both pulled high via 4.7Kohm resistors. If I understand correctly, you do not use constants in the I2CWRITE syntax; use variables only.

    I cant for the life of me figure this out. What would be the correct form for I2CWRITE to utilize this display.
    Any help would be greatly appreciated.

    Thanks Sean Harmon


    Here is a link to the datasheet for the SAA1064. http://www.nxp.com/documents/data_sheet/SAA1064_CNV.pdf

    Here is some info from the datasheet:


    Name:  SAA1064_Display-Module.jpg
Views: 1301
Size:  78.7 KB
    Name:  SAA1064_Display-Module_Page_06.jpg
Views: 1192
Size:  84.0 KB

    Name:  SAA1064_Display-Module_Page_07.jpg
Views: 1113
Size:  74.8 KB
    "Reality is merely an illusion, albeit a very persistent one." , Albert Einstein

  2. #2
    Join Date
    Nov 2003
    Location
    Wellton, U.S.A.
    Posts
    5,924


    Did you find this post helpful? Yes | No

    Default Re: Problems with I2CWRITE and the SAA1064 Seven-Segment Controller

    I have not used the part you are having trouble with, but this might help you understand the I2C commands better.
    http://www.picbasic.co.uk/forum/cont...-EEPROM-Part-1
    Dave
    Always wear safety glasses while programming.

  3. #3
    Join Date
    Mar 2010
    Location
    Serbia
    Posts
    2


    Did you find this post helpful? Yes | No

    Default Re: Problems with I2CWRITE and the SAA1064 Seven-Segment Controller

    Code:
    SYMBOL SDA=PORTA.O              'this is just an example
    SYMBOL SCL=PORTA.1              'you can use other ports
    
    '---------------senging four digits to SAA1064--------------------------------------
    
    I2CWRITE SDA,SCL,$70,0,$B7,[dig1,dig2,dig3,dig4]

    $70 is adress byte, you allready have that fixed,
    0 is instruction byte, by this you tell the chip that next byte is control byte (see datasheet, first line in subadressing),
    and every following byte is written from this point.

    $B7 is control byte or 10110111 and means:

    0 bit determines are you in static (2 digits) or dynamic multiplex (4 digits) mode
    1 bit turns off/on digits 1 and 3
    2 bit turns off/on digits 2 and 4
    3 bit is used for testing all segments, normally is 0
    4 bit +3mA
    5 bit +6mA
    6 bit +12mA
    7 bit not used, could be anything

    So, $B7 would be: you are in dynamic mode, 4 digits on, not testing, 3+6=9mA into segments.
    Or, it could be $77: you are in dynamic mode, 4 digits on, not testing, 3+6+12=21mA into segments.
    You send digits in hex, for an example $7D is number 7.
    You can send constants with I2CWRITE or use variables for control registers and change them wherever you want in program.

    My english is not so good so....sorry if I made any mistakes.

  4. #4
    Join Date
    Jun 2011
    Location
    St. Louis, MO
    Posts
    13


    Did you find this post helpful? Yes | No

    Default Re: Problems with I2CWRITE and the SAA1064 Seven-Segment Controller

    Thanks mackrackit and misamilanovic for the replies. I did not succeed in using I2CWRITE but was successful using SHIFTIN/SHIFOUT.
    Check out my blog post HERE for more details.
    But here is the PICBASIC code for a 16F88 that counts from 0-9 on all four digits.

    Code:
    '// for 4MHZ
    DEFINE OSC 4
    OSCCON=%01101000
    '// for 8MHZ
    'DEFINE OSC 8
    'OSCCON=%01111000
    While OSCCON.2=0:Wend
    CMCON         =  7                 '// PORTA = digital I/O
    'OPTION_REG.7  =  0                 '// Enable PORTB pull-ups
    ADCON1        =  7
    ANSEL=%00000000                    '// set all analog pins to digital
    ANSEL = 0                          '// disable ADCs
    TRISB.3 = 0
    TRISB.2 = 0
    '----------------------------------------------------------------------------
    led         var PORTA.1
    SDA         VAR PORTB.3
    SCL         VAR PORTB.2
    i2c_dev     var byte        'I2C device Address 
    i2c_out     VAR BYTE        'data to sent over I2C bus
    i2c_ack     VAR BIT         'acknowledgement bit
    i           var byte
    segment     VAR byte
    seg_val     var byte
    '----------------------------------------------------------------------------
    i2c_dev = %01110000        '(112 = %01110000 = $70)
    gosub startup 
    GOSUB init_display   'initialize the display module
    main:
       GOSUB COUNTER
       goto main
       END
        
    counter:
        for i = 0 to 9
            lookup i, [189,9,117,109,201,236,248,13,253,205],seg_val
            for segment = 1 to 4
                  GOSUB I2C_START
                  if segment = 1 then
                     i2c_out = %01110000 : gosub i2C_tx : i2c_out = %00000001 : gosub i2C_tx
                     i2c_out = seg_val : gosub i2c_tx
                     gosub i2c_stop
                  endif
                  if segment = 2 then
                     i2c_out = %01110000 : gosub i2C_tx : i2c_out = %00000010 : gosub i2C_tx
                     i2c_out = seg_val : gosub i2c_tx
                     gosub i2c_stop
                  endif
                  if segment = 3 then    
                     i2c_out = %01110000 : gosub i2C_tx : i2c_out = %00000011 : gosub i2C_tx
                     i2c_out = seg_val : gosub i2c_tx
                     gosub i2c_stop
                  endif
                  if segment = 4 then    
                     i2c_out = %01110000 : gosub i2C_tx : i2c_out = %00000100 : gosub i2C_tx
                     i2c_out = seg_val : gosub i2c_tx
                     gosub i2c_stop
                  endif
              next segment
            pause 100 
          next i
        return
    
    bit_cycle:
        for i = 0 to 255
           gosub i2c_start
           i2c_out = %01110000 : gosub i2C_tx : i2c_out = %00000001 : gosub i2C_tx
           i2c_out = i
           gosub i2C_tx
           gosub i2c_stop
        pause 20
        next i
        
    return
    init_display:           'initialize the SAA1064 module and flash all segments
        GOSUB I2C_START     'Start the I2C communication
           i2c_out = %01110000 : GOSUB I2C_TX        'send device byte
           i2c_out = %00000000 : GOSUB I2C_TX        'send instruction byte 
           i2c_out = %00011111 : GOSUB I2C_TX        'send control byte    
        GOSUB I2C_STOP      'Stop i2C transmission
        pause 1000          ' leave segments on for 1 sec then turn off
        
        GOSUB I2C_START
           i2c_out = %01110000 : gosub i2C_tx
           i2c_out = %00000000 : gosub i2C_tx
           i2c_out = %00000001 : GOSUB I2C_TX
        GOSUB I2C_STOP
        pause 500
        
        GOSUB I2C_START
           i2c_out = %01110000 : gosub i2C_tx
           i2c_out = %00000000 : gosub i2C_tx
           i2c_out = %00010111 : GOSUB I2C_TX
        GOSUB I2C_STOP
      RETURN
    
    I2C_START:              
        HIGH SDA
        HIGH SCL
        LOW SDA
       RETURN
     
    I2C_STOP:               'I2C stop (terminate communication on I2C bus)
        HIGH SCL
        HIGH SDA
        PAUSE 1
        RETURN
     
    I2C_TX:                           'I2C transmit -> send data to the slave
        SHIFTOUT SDA,SCL,1,[i2c_out]  'Shift out “i2c_out” MSBfirst
        SHIFTIN SDA,SCL,0,[i2c_ack\1] 'Receive ACK bit          
        RETURN
    '// start-up led sequence
    startup: 
      for i = 0 to 4
        high led
        pause 50
        low led
        pause 30
      next i
      pause 300
    Return
    "Reality is merely an illusion, albeit a very persistent one." , Albert Einstein

Members who have read this thread : 1

You do not have permission to view the list of names.

Tags for this Thread

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts