Problems with I2CWRITE and the SAA1064 Seven-Segment Controller

[triton99]

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:




[mackrackit]

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

[misamilanovic]

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.

[triton99]

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.

'// 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