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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML EXPERIMENTAL 970324//EN"><HTML><HEAD><META NAME="GENERATOR" CONTENT="Adobe FrameMaker 5.5/HTML Export Filter"><LINK REL="STYLESHEET" HREF="ch07.css"><TITLE> 7.14 Strengths of net types</TITLE></HEAD><BODY BGCOLOR="#ffffff"><DIV><HR><P><A HREF="ch07.htm">Chapter start</A> <A HREF="ch07.d.htm">Previous page</A> <A HREF="ch07.f.htm">Next page</A></P></DIV><H1 CLASS="Section"><A NAME="pgfId=1646"> </A>7.14 <A NAME="83929"> </A>Strengths of net types</H1><P CLASS="Body"><A NAME="pgfId=1647"> </A>The <B CLASS="Keyword">tri0</B>, <B CLASS="Keyword">tri1</B>, <B CLASS="Keyword">supply0</B>, and <B CLASS="Keyword">supply1</B> net types shall generate signals with specific strength levels. The <B CLASS="Keyword">trireg</B> declaration can specify either of two signal strength levels other than a default strength level.</P><P CLASS="SubSection"><A NAME="pgfId=1648"> </A><A NAME="83556"> </A><A NAME="marker=563"> </A><A NAME="marker=564"> </A>Tri0 and <A NAME="marker=565"> </A><A NAME="marker=566"> </A>tri1 net strengths </P><P CLASS="Body"><A NAME="pgfId=1043"> </A>The <B CLASS="Keyword">tri0</B> net type models a net connected to a resistive <B CLASS="Keyword">pulldown</B> device. In the absence of an overriding source, such a signal shall have a value <CODE CLASS="code">0</CODE> and a <B CLASS="Keyword">pull</B> strength. The <B CLASS="Keyword">tri1</B> net type models a net connected to a resistive <B CLASS="Keyword">pullup</B> device. In the absence of an overriding source, such a signal shall have a value <CODE CLASS="code">1</CODE> and a <B CLASS="Keyword">pull</B> strength.</P><P CLASS="SubSection"><A NAME="pgfId=1649"> </A><A NAME="64748"> </A><A NAME="marker=568"> </A><A NAME="marker=569"> </A>Trireg strength </P><P CLASS="Body"><A NAME="pgfId=1650"> </A>The <B CLASS="Keyword">trireg</B> net type models charge storage nodes. The strength of the drive resulting from a <B CLASS="Keyword">trireg</B> net that is in the charge storage state (that is, a driver charged the net and then went to high impedance) shall be one of these three strengths: <B CLASS="Keyword">large</B>, <B CLASS="Keyword">medium</B>, or <B CLASS="Keyword">small</B>. The specific strength associated with a particular <B CLASS="Keyword">trireg</B> net shall be specified by the user in the net declaration. The default shall be <B CLASS="Keyword">medium</B>. The syntax of this specification is described in <A HREF="/Humuhumu/Files/Prof_Smith/Academic/ASICs/Web/ASICs/HTML/Verilog/LRM/HTML/07/ch03.htm#47037" CLASS="XRef"></A>.</P><P CLASS="SubSection"><A NAME="pgfId=1651"> </A>S<A NAME="marker=573"> </A><A NAME="marker=574"> </A>upply0 and supply1 net strengths </P><P CLASS="Body"><A NAME="pgfId=1652"> </A>The <B CLASS="Keyword">supply0</B> net type models ground connections. The <B CLASS="Keyword">supply1</B> net type models connections to power supplies. The <B CLASS="Keyword">supply0</B> and <B CLASS="Keyword">supply1</B> net types shall have <B CLASS="Keyword">supply</B> driving <A NAME="marker=575"> </A>strengths<A NAME="marker=576"> </A>.</P><HR><P><A HREF="ch07.htm">Chapter start</A> <A HREF="ch07.d.htm">Previous page</A> <A HREF="ch07.f.htm">Next page</A></P></BODY></HTML>?? 快捷鍵說明
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