First I haven't used this chip and Second I'm not a great C
programmer, but I'm a little confused by your

 if(shift_left(write_value,1,0))// Shift in MSB first

part of the program.

Would it not be easier to do

void out_74595(unsigned char shift_data)
{
=09unsigned char bitcount,bitmask;
=09
=09bitmask=3D1<<bit_no;
=09
=09for (bitcount=3D8;bitcount; bitcount--)
=09{
=09  if (shift_data&1)=09=09//LSB first
=09  {
=09    shiftport|=3Dbitmask;=09=09//
=09  }
=09  else
=09  {
=09    shiftport&=3D~bitmask;
=09  }
=09
=09  //Wait(1000); =09=09//for debugging=09
=09  clockport^=3D1<<clockbit;    //clock data in 74H595
=09  //Wait(1000);=09                //for debugging
=09  clockport^=3D1<<clockbit;
=09  shift_data>>=3D1;=09     //Next data bit
=09}
=09
=09  latchport^=3D1<<latchbit;    //All done latch data to 595=
 outputs
=09  //Wait(1000);=09=09=09//for debugging
=09  latchport^=3D1<<latchbit;
=09 // Wait(1000);=09=09=09//for debugging
=09
=09


}

This I wrote to talk to an LCD via an 74HC595 (I realise yours is=
 a
slightly different chip but the ideas the same). This is written=
 in
FED C. To do MSB instead of LSB just AND with 0XFF instead of=
 0x01.

colin
--
cdb, bodgy1@optusnet.com.au on 09/05/2002

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