toggling an output

[tony rudzki]

This is a pretty simple question:

How can you toggle an output signal in VHDL? I make 'amberout' an Output
and in a counter, when I count down to 0, I want to toggle the output. I'm
using :

amberout <= not amberout;

but this generates erors in Galaxy 5.2 (cypress). The error I get is:

'amberout' not readable. Mode is OUT.

any help would be appreciated

Tony

[dmac]

An output cannot be read, either:
1 define port as inout (less preferred)
or
2. declare an intermediate signal: (more preferred)
amber <= not amber; -- within clocked process
amberout <= amber; -- outside clocked process
this does not use any extra resources.
A common convention is to use suffix _i for intermediate signals to show
what you're up to:
amber_i <= not amber_i; -- clocked
amber <= amber_i; -- unclocked

Dave

tony rudzki <tony....@nu-metrics.com> writes

--
dmac

[weede...@gmail.com]

Thank you for this answer. It was helpful to me.