Pin Keyword
Syntax
[!]pin_id[,[!]pin_id...] PIN [pin_name[,pin_name]] [ISTYPE 'attr'];
pin_id - An identifier used to refer to a pin signal throughout a module.
pin_name - The pin number or name on the real device.
attr - A string that specifies pin attributes for devices with programmable pins.
Use
The PIN keyword is used to declare those input and output signals that must eventually be available on a device I/O pin. You should also specify pin attributes for all pins used as outputs.
When lists of pin_ids and pin_names are used in one pin declaration statement, there is a one-to-one correspondence between the identifiers and numbers given. If you declare pin names, you must include names for each identifier listed in the statement.
For CSP and BGA type packages with alphanumeric row-column pin names, enclose each pin name in single-quotes. For example:
a pin 'B2' istype 'reg';
Example
!Clock, Reset, S1 PIN 12,15,3;
This pin declaration assigns the pin id Clock to pin number 12; Reset to pin #15; and S1 to pin #3.
The use of the "!' operator in pin declarations indicates that the pin is active-low and will be automatically negated when processed by the language processor.
Errors
The following are pin assignment errors that cause errors in ABEL:
Assigning the same pin number to two
signals (A1, A0 pin 17,17;).