How to set port to high impedance? TRIS seems not to be working.

[mpgmike]

In your example code you clear all TRIS bits making them all outputs. Try:

TRISA = 111111
TRISB = 111111
TRISC = 111111

frak:
TRISA.6 = 0
TRISC.3 = 0
HIGH PORTA.6
LOW PORTC.3
PAUSE 2
LOW PORTA.6
HIGH PORTC.3
PAUSE 2
TRISA.6 = 1
TRISC.3 = 1

TRISC.1 = 0
TRISC.2 = 0
HIGH PORTC.1
LOW PORTC.2
PAUSE 2
LOW PORTC.1
HIGH PORTC.2
PAUSE 2
TRISC = 0
GOTO frak