Hi
Ive got a programmed TIP16L8ACN.
Does anybody know of an easy way to work out the
programmed logic.
It looks to have 10 dedicated i/ps, 2 dedicated o/ps
and 6 don't care.
Not sure where to start so if any body has found a way
using simple tools I'd sure like to hear.
Regards
Harry w
Hi
L's are easy. They are just logic with no state.
Get a number of LED's and some resistors. About
680 or 750 is a good size to use. For each output
use two LEDs. Drive one of these LEDs through
an inverter, like a 7404.
If it is an input you can hard drive it high or low.
If it is one of the 6 that can be input or output,
disconnect the LED/resistor and use just one of the
resistors to pull it high or low. Try all the combinations.
If one of the 6 changes when one of those that are
known to be inputs then don't bother trying to
check it as an input. Record any combination of
inputs that produces a change to outputs. You
should then be able to create a truth table for
it.
I wouldn't use the term don't care for the six pins.
They are usually programed to be either an input
or an output. In rare cases, they may be programmed
to be feedbacks. This is bad because this can
hold state that is harder to detect from the outside.
Most are used as address decoders and don't use
the feedback.
In the case of address decoders, it is usually just
simple logic. You just need to determine if the six
I/Os are programmed as inputs or outputs. Any
It is also rare that they use the 3-state line for
other than a fixed input or output.
Dwight
