Problems with I2CWRITE and the SAA1064 Seven-Segment Controller

3 Attachment(s)

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:

Attachment 6136
Attachment 6137
Attachment 6138

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

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.

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