hello all

last year i had a problem on these inputs also. i had a keypad matrix with RB0-3 as outputs (with diode) and RB4-7 as inputs (external pull downs, no interrupts!). with a keypad with a cable of 20cm it ever works fine. later in the installation with a keypad cable of about 150cm, after a while the pic ever seems frozen in a state where he never came back. because i hadn't much time then i solved the problem when i changed the inputs RB4-7 to RC0-3 where the longer cabel never was a problem.
some idea what that could be then?

now, RB5-7 are inputs with internal pull up and interrupt. the pic-board is powered by a power supply. i have an old soldering iron. when i turn it out, i get some short noise over 230V back to the 5V of my pic. then an interrupt is initialised over my RB5-7 inputs. i solved it now with a 10ms delay in the begin of the interrput servide routine and asking RB5-7 back again before execute the code.
but what could be the reason for this? that the pull up of RB5-7 are connected to 5V....

sorry for this mystified characterisation and thanks for any ideas