Colin, I tried your C code, no go. As it's the same as what I was doing anyway that's no great surprise. Actually a relief. I shouldn't need to use a compiler's output to check my assembly code So I told MChip. Their response - ---------- # you need to modify the following instructions: RPINR20bits.SDI1R =3D 17; // SDI1, RP17-RC1, pin 26, value 17 =3D RP17 RPOR8bits.RP16R =3D 7; // SDO1, RP16-RC0, pin 25, value 7 =3D 00111 =3D S= DO1 RPOR9bits.RP18R =3D 8; // SCK1, RP18-RC2, pin 27, value 8 =3D 01000 =3D S= CK1 ---------- Hmmm, OK. You do know that pin 27 on *my* PIC is AVss ? And 25, 26 are DAC outputs, pretty much the reason for the product ? Sorry to sound snotty but I really get the feeling MChip Support is trying to make me do all the work, and spend the $$$, until I fit their solution It's frustrating that the tech hasn't tried my code in my PIC, but instead written his own s/w for a PIC of his choosing. So, after three weeks we're back to square one. "Here's my code, why doesn't it work ?" ;-( [and not for the first time with MChip Support] Joe --=20 http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .