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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"><html><head><meta http-equiv="Content-Type" content="text/html;charset=iso-8859-1"><title>Procyon AVRlib: sramsw.c Source File</title><link href="dox.css" rel="stylesheet" type="text/css"></head><body><!-- Generated by Doxygen 1.4.2 --><div class="qindex"><a class="qindex" href="main.html">Main Page</a> | <a class="qindex" href="modules.html">Modules</a> | <a class="qindex" href="annotated.html">Data Structures</a> | <a class="qindex" href="dirs.html">Directories</a> | <a class="qindex" href="files.html">File List</a> | <a class="qindex" href="functions.html">Data Fields</a> | <a class="qindex" href="globals.html">Globals</a> | <a class="qindex" href="pages.html">Related Pages</a></div><h1>sramsw.c</h1><a href="sramsw_8c.html">Go to the documentation of this file.</a><div class="fragment"><pre class="fragment">00001 <span class="comment">/*! \file sramsw.c \brief Software-driven SRAM memory bus access functions. */</span>00002 <span class="comment">//*****************************************************************************</span>00003 <span class="comment">//</span>00004 <span class="comment">// File Name : 'sramsw.c'</span>00005 <span class="comment">// Title : Software-driven SRAM memory bus access functions</span>00006 <span class="comment">// Author : Pascal Stang - Copyright (C) 2002</span>00007 <span class="comment">// Created : 11/11/2002</span>00008 <span class="comment">// Revised : 11/13/2002</span>00009 <span class="comment">// Version : 1.0</span>00010 <span class="comment">// Target MCU : Atmel AVR series</span>00011 <span class="comment">// Editor Tabs : 4</span>00012 <span class="comment">//</span>00013 <span class="comment">// This code is distributed under the GNU Public License</span>00014 <span class="comment">// which can be found at http://www.gnu.org/licenses/gpl.txt</span>00015 <span class="comment">//</span>00016 <span class="comment">//*****************************************************************************</span>00017 00018 <span class="preprocessor">#include <avr/io.h></span>00019 <span class="preprocessor">#include <avr/interrupt.h></span>00020 00021 <span class="preprocessor">#include "<a class="code" href="global_8h.html">global.h</a>"</span>00022 <span class="preprocessor">#include "<a class="code" href="sramsw_8h.html">sramsw.h</a>"</span>00023 00024 <span class="comment">// global variables</span>00025 00026 <span class="comment">// functions</span><a name="l00027"></a><a class="code" href="sramsw_8h.html#a0">00027</a> <span class="keywordtype">void</span> <a class="code" href="sramsw_8c.html#a0">sramswInit</a>(<span class="keywordtype">void</span>)00028 {00029 <span class="comment">// initialize port state</span>00030 outb(SRAM_ADL, 0xFF); <span class="comment">// addr/data port set to 0xFF (pull-ups enabled)</span>00031 outb(SRAM_AH, 0x00); <span class="comment">// high addr port set to 0x00</span>00032 <span class="comment">// initialize port directions</span>00033 outb(SRAM_ADL_DDR, 0x00); <span class="comment">// addr/data port set to input</span>00034 outb(SRAM_AH_DDR, 0xFF); <span class="comment">// high addr port set to output</span>00035 <span class="comment">// initialize control line states</span>00036 sbi(SRAM_CTRL, SRAM_WR); <span class="comment">// de-assert write (active low)</span>00037 sbi(SRAM_CTRL, SRAM_RD); <span class="comment">// de-assert read (active low)</span>00038 cbi(SRAM_CTRL, SRAM_ALE); <span class="comment">// de-assert ALE (active high)</span>00039 <span class="comment">// set control line direction</span>00040 sbi(SRAM_CTRL_DDR, SRAM_WR);00041 sbi(SRAM_CTRL_DDR, SRAM_RD);00042 sbi(SRAM_CTRL_DDR, SRAM_ALE);00043 <span class="comment">// set page lines direction</span>00044 outb(SRAM_PAGE_DDR, inb(SRAM_PAGE_DDR) | SRAM_PAGE_MASK );00045 <span class="comment">// initialize page</span>00046 <a class="code" href="sramsw_8c.html#a4">sramswSetPage</a>(0);00047 }00048 00049 <span class="keywordtype">void</span> sramswOff(<span class="keywordtype">void</span>)00050 {00051 }00052 <a name="l00053"></a><a class="code" href="sramsw_8h.html#a1">00053</a> <span class="keywordtype">void</span> <a class="code" href="sramsw_8c.html#a2">sramswWrite</a>(u32 addr, u08 data)00054 {00055 <span class="comment">// set page</span>00056 <a class="code" href="sramsw_8c.html#a4">sramswSetPage</a>( (addr & 0x00FF0000)>>16 );00057 <span class="comment">// set high-order address</span>00058 outb(SRAM_AH, (addr & 0x0000FF00)>>8 );00059 <span class="comment">// set low-order address</span>00060 outb(SRAM_ADL, addr & 0x000000FF);00061 <span class="comment">// apply low-order address to latch</span>00062 outb(SRAM_ADL_DDR, 0xFF);00063 <span class="comment">// clock latch to save low-order address</span>00064 sbi(SRAM_CTRL, SRAM_ALE); <span class="comment">// assert ALE (active high)</span>00065 <span class="keyword">asm</span> <span class="keyword">volatile</span> (<span class="stringliteral">"nop"</span>);00066 cbi(SRAM_CTRL, SRAM_ALE); <span class="comment">// de-assert ALE (active high)</span>00067 00068 <span class="comment">// apply data to memory</span>00069 outb(SRAM_ADL, data);00070 <span class="comment">// clock write line to store data</span>00071 cbi(SRAM_CTRL, SRAM_WR); <span class="comment">// assert write (active low)</span>00072 <span class="keyword">asm</span> <span class="keyword">volatile</span> (<span class="stringliteral">"nop"</span>);00073 sbi(SRAM_CTRL, SRAM_WR); <span class="comment">// de-assert write (active low)</span>00074 }00075 <a name="l00076"></a><a class="code" href="sramsw_8h.html#a2">00076</a> u08 <a class="code" href="sramsw_8c.html#a3">sramswRead</a>(u32 addr)00077 {00078 u08 data;00079 00080 <span class="comment">// set page</span>00081 <a class="code" href="sramsw_8c.html#a4">sramswSetPage</a>( (addr & 0x00FF0000)>>16 );00082 <span class="comment">// set high-order address</span>00083 outb(SRAM_AH, (addr & 0x0000FF00)>>8 );00084 <span class="comment">// set low-order address</span>00085 outb(SRAM_ADL, addr & 0x000000FF);00086 <span class="comment">// apply low-order address to latch</span>00087 outb(SRAM_ADL_DDR, 0xFF);00088 <span class="comment">// clock latch to save low-order address</span>00089 sbi(SRAM_CTRL, SRAM_ALE); <span class="comment">// assert ALE (active high)</span>00090 <span class="keyword">asm</span> <span class="keyword">volatile</span> (<span class="stringliteral">"nop"</span>);00091 cbi(SRAM_CTRL, SRAM_ALE); <span class="comment">// de-assert ALE (active high)</span>00092 00093 <span class="comment">// switch data bus to input</span>00094 outb(SRAM_ADL_DDR, 0x00);00095 <span class="comment">// clear pullups</span>00096 outb(SRAM_ADL, 0x00);00097 <span class="comment">// request data from memory</span>00098 cbi(SRAM_CTRL, SRAM_RD); <span class="comment">// assert read (active low)</span>00099 <span class="comment">// retrieve data</span>00100 <span class="keyword">asm</span> <span class="keyword">volatile</span> (<span class="stringliteral">"nop"</span>);00101 data = inb(SRAM_ADL_IN);00102 <span class="comment">// release read line</span>00103 sbi(SRAM_CTRL, SRAM_RD); <span class="comment">// de-assert read (active low)</span>00104 <span class="comment">// switch data bus to output</span>00105 outb(SRAM_ADL_DDR, 0xFF);00106 00107 <span class="keywordflow">return</span> data;00108 }00109 <a name="l00110"></a><a class="code" href="sramsw_8h.html#a3">00110</a> <span class="keywordtype">void</span> <a class="code" href="sramsw_8c.html#a4">sramswSetPage</a>(u08 page)00111 {00112 outb(SRAM_PAGE, (page & SRAM_PAGE_MASK));00113 }</pre></div><hr size="1"><address style="align: right;"><small>Generated on Sun Oct 29 03:41:07 2006 for Procyon AVRlib by <a href="http://www.doxygen.org/index.html"><img src="doxygen.png" alt="doxygen" align="middle" border="0"></a> 1.4.2 </small></address></body></html>⌨️ 快捷键说明
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