StaffHow to ad Technology Labels to your schematic/netlist
A technology label is an optional field in the netlist which may exist to the right of the semi-colon (;) in a net record and be enclosed in parentheses. A technology label is a user (Customer or Speedwell Designs) definable label which is used to group nets to be handled in a particular manner. In many cases, different sections or nets on the board should be handled with completely different design rules. The technology label is the method of identifying these rules. A legend or set of instructions is also required, in order to convey what the user intends for each of the given labels. While this tool is completely user definable, some examples of this are:
| Technology Label | Meaning |
|---|---|
| clk_ttl | ttl clocks, daisy chain w/ no terminate at end, route single channel, use ttl layers only. |
| clk_ecl | ecl clocks, daisy chain w/ no stubs terminate at end route single channel, use ecl layers only. |
| ecl | ecl nets, terminate w/ 50 ohm to -2v, 100 mils to any ttl net, no stubs allowed, term wire 1" max. |
| fttl | F family ttl logic, 100 mils to any ecl net, 8 mil line minimum, 2" max. stub length |
| ctl_ttl | ttl control logic and asynchronous logic, route single channel |
| pwr | use 100 mil line minimum, use outer layers only |
| ****** | unmarked nets are ttl goo, use good ttl design rules still 100 mils to ecl nets |
In an actual netlist, the technology label might look like this:
CLK1 ; (clk_ttl) U7.1 U10.5 U20.8 R3.1 R4.1
The technology label can be annotated into the netlist in any number of ways. It can be annotated manually into the netlist with the use of a marked up schematic, there can be an ascii file with the name of the technology containing a list of netnames, or embedded in the netlist by a data reformatter (certainly the most desirable). The most reliable method of adding these labels is by the engineer at the schematic level. Most modern CAE systems provide a method to attach properties to a net on the schematic, which can be used to pass on information to downstream tools such as the netlister. Since any number of various CAE tools may be used, it is impossible for us to describe exactly how to add these properties on a given system. However, our experience shows that this task is not usually difficult to implement, and is relatively easy to figure out Once the data is in the system and a method of extraction is identified, the engineer has a perfect vehicle for conveying net-related interconnect data. In some cases, we have actually seen the engineer put the legend on the schematic sheet in the form of notes.
