LCD I2C Strangeness (waveform included)

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i'm trying interface i2c lcd (http://www.newhavendisplay.com/specs/nhd-c0216ciz-fsw-fbw-3v3.pdf) arduino.  i'm pretty sure have wiring hooked correctly (including mosfet based level conversion) looking @ waveforms on scope.

here initialization code got library francisco (had modify few things lcd).
code: [select]

  wire.begin();
  wire.begintransmission ( _i2caddress );
  wire.write ( (byte)0x0 );   // send command display
  wire.write ( func_set_tbl0 );
  delay (10);
  wire.write ( func_set_tbl1 );
  delay (10);
  wire.write ( 0x14 );  // set bias - 1/5
  wire.write ( 0x78 );  // set contrast low byte
  wire.write ( 0x5e );  // icon disp on, booster on, contrast high byte
  wire.write ( 0x6d );  // follower circuit (internal), amp ratio (6)
  wire.write ( 0x0c );  // display on
  wire.write ( 0x01 );  // clear display
  wire.write ( 0x06 );  // entry mode set - increment
  delay(10);
  _status = wire.endtransmission ();
 
  serial.println(_status);


if @ waveform logic analyzer i'm getting valid ack lcd slave address byte.  here's image: http://www.glacialwanderer.com/_blog/blog2012/april/i2c_debug.png

i have tried putting in wrong slave address , nak.  so seems lcd sending ack back.  basically looks me, after slave address byte , ack broken.  in code above i'm writing lot more bytes , none of shows on waveform.  also _status i'm printing out in code 2 (failure address nak).  so reason seems arduino failing send bytes after intial address , don't know why.  does have ideas on going wrong?

i'm trying interface i2c lcd (http://www.newhavendisplay.com/specs/nhd-c0216ciz-fsw-fbw-3v3.pdf) arduino.

i have found more information.  looking @ 3.3 side of i2c bus looks fine.  but, when @ 5v side of bus (master/arduino) don't ack , fails.

here level conversion circuit:


the things possibly matter mosfets.  i'm using there: http://www.mouser.com/productdetail/fairchild-semiconductor/fqn1n50cta/?qs=sgaepimzzmsrr1kxjis%252bjwanxo1jtn8amqxukbegcxu%3d

does have idea what's going wrong , why when 3.3 side of i2c bus pulled low 5v side of bus not pulled low?


Arduino Forum > Using Arduino > Networking, Protocols, and Devices (Moderator: fabioc84) > LCD I2C Strangeness (waveform included)


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