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| 3 | <title>Procyon AVRlib: sramsw.c Source File</title> |
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| 8 | <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> |
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| 9 | 00002 <span class="comment">//*****************************************************************************</span> |
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| 10 | 00003 <span class="comment">//</span> |
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| 11 | 00004 <span class="comment">// File Name : 'sramsw.c'</span> |
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| 12 | 00005 <span class="comment">// Title : Software-driven SRAM memory bus access functions</span> |
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| 13 | 00006 <span class="comment">// Author : Pascal Stang - Copyright (C) 2002</span> |
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| 14 | 00007 <span class="comment">// Created : 11/11/2002</span> |
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| 15 | 00008 <span class="comment">// Revised : 11/13/2002</span> |
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| 16 | 00009 <span class="comment">// Version : 1.0</span> |
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| 17 | 00010 <span class="comment">// Target MCU : Atmel AVR series</span> |
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| 18 | 00011 <span class="comment">// Editor Tabs : 4</span> |
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| 19 | 00012 <span class="comment">//</span> |
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| 20 | 00013 <span class="comment">// This code is distributed under the GNU Public License</span> |
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| 21 | 00014 <span class="comment">// which can be found at http://www.gnu.org/licenses/gpl.txt</span> |
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| 22 | 00015 <span class="comment">//</span> |
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| 23 | 00016 <span class="comment">//*****************************************************************************</span> |
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| 24 | 00017 |
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| 25 | 00018 <span class="preprocessor">#include <avr/io.h></span> |
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| 26 | 00019 <span class="preprocessor">#include <avr/interrupt.h></span> |
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| 27 | 00020 |
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| 28 | 00021 <span class="preprocessor">#include "<a class="code" href="global_8h.html">global.h</a>"</span> |
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| 29 | 00022 <span class="preprocessor">#include "<a class="code" href="sramsw_8h.html">sramsw.h</a>"</span> |
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| 30 | 00023 |
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| 31 | 00024 <span class="comment">// global variables</span> |
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| 32 | 00025 |
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| 33 | 00026 <span class="comment">// functions</span> |
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| 34 | <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>) |
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| 35 | 00028 { |
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| 36 | 00029 <span class="comment">// initialize port state</span> |
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| 37 | 00030 outb(SRAM_ADL, 0xFF); <span class="comment">// addr/data port set to 0xFF (pull-ups enabled)</span> |
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| 38 | 00031 outb(SRAM_AH, 0x00); <span class="comment">// high addr port set to 0x00</span> |
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| 39 | 00032 <span class="comment">// initialize port directions</span> |
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| 40 | 00033 outb(SRAM_ADL_DDR, 0x00); <span class="comment">// addr/data port set to input</span> |
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| 41 | 00034 outb(SRAM_AH_DDR, 0xFF); <span class="comment">// high addr port set to output</span> |
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| 42 | 00035 <span class="comment">// initialize control line states</span> |
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| 43 | 00036 sbi(SRAM_CTRL, SRAM_WR); <span class="comment">// de-assert write (active low)</span> |
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| 44 | 00037 sbi(SRAM_CTRL, SRAM_RD); <span class="comment">// de-assert read (active low)</span> |
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| 45 | 00038 cbi(SRAM_CTRL, SRAM_ALE); <span class="comment">// de-assert ALE (active high)</span> |
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| 46 | 00039 <span class="comment">// set control line direction</span> |
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| 47 | 00040 sbi(SRAM_CTRL_DDR, SRAM_WR); |
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| 48 | 00041 sbi(SRAM_CTRL_DDR, SRAM_RD); |
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| 49 | 00042 sbi(SRAM_CTRL_DDR, SRAM_ALE); |
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| 50 | 00043 <span class="comment">// set page lines direction</span> |
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| 51 | 00044 outb(SRAM_PAGE_DDR, inb(SRAM_PAGE_DDR) | SRAM_PAGE_MASK ); |
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| 52 | 00045 <span class="comment">// initialize page</span> |
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| 53 | 00046 <a class="code" href="sramsw_8c.html#a4">sramswSetPage</a>(0); |
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| 54 | 00047 } |
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| 55 | 00048 |
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| 56 | 00049 <span class="keywordtype">void</span> sramswOff(<span class="keywordtype">void</span>) |
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| 57 | 00050 { |
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| 58 | 00051 } |
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| 59 | 00052 |
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| 60 | <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) |
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| 61 | 00054 { |
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| 62 | 00055 <span class="comment">// set page</span> |
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| 63 | 00056 <a class="code" href="sramsw_8c.html#a4">sramswSetPage</a>( (addr & 0x00FF0000)>>16 ); |
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| 64 | 00057 <span class="comment">// set high-order address</span> |
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| 65 | 00058 outb(SRAM_AH, (addr & 0x0000FF00)>>8 ); |
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| 66 | 00059 <span class="comment">// set low-order address</span> |
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| 67 | 00060 outb(SRAM_ADL, addr & 0x000000FF); |
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| 68 | 00061 <span class="comment">// apply low-order address to latch</span> |
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| 69 | 00062 outb(SRAM_ADL_DDR, 0xFF); |
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| 70 | 00063 <span class="comment">// clock latch to save low-order address</span> |
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| 71 | 00064 sbi(SRAM_CTRL, SRAM_ALE); <span class="comment">// assert ALE (active high)</span> |
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| 72 | 00065 <span class="keyword">asm</span> <span class="keyword">volatile</span> (<span class="stringliteral">"nop"</span>); |
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| 73 | 00066 cbi(SRAM_CTRL, SRAM_ALE); <span class="comment">// de-assert ALE (active high)</span> |
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| 74 | 00067 |
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| 75 | 00068 <span class="comment">// apply data to memory</span> |
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| 76 | 00069 outb(SRAM_ADL, data); |
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| 77 | 00070 <span class="comment">// clock write line to store data</span> |
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| 78 | 00071 cbi(SRAM_CTRL, SRAM_WR); <span class="comment">// assert write (active low)</span> |
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| 79 | 00072 <span class="keyword">asm</span> <span class="keyword">volatile</span> (<span class="stringliteral">"nop"</span>); |
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| 80 | 00073 sbi(SRAM_CTRL, SRAM_WR); <span class="comment">// de-assert write (active low)</span> |
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| 81 | 00074 } |
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| 82 | 00075 |
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| 83 | <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) |
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| 84 | 00077 { |
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| 85 | 00078 u08 data; |
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| 86 | 00079 |
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| 87 | 00080 <span class="comment">// set page</span> |
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| 88 | 00081 <a class="code" href="sramsw_8c.html#a4">sramswSetPage</a>( (addr & 0x00FF0000)>>16 ); |
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| 89 | 00082 <span class="comment">// set high-order address</span> |
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| 90 | 00083 outb(SRAM_AH, (addr & 0x0000FF00)>>8 ); |
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| 91 | 00084 <span class="comment">// set low-order address</span> |
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| 92 | 00085 outb(SRAM_ADL, addr & 0x000000FF); |
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| 93 | 00086 <span class="comment">// apply low-order address to latch</span> |
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| 94 | 00087 outb(SRAM_ADL_DDR, 0xFF); |
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| 95 | 00088 <span class="comment">// clock latch to save low-order address</span> |
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| 96 | 00089 sbi(SRAM_CTRL, SRAM_ALE); <span class="comment">// assert ALE (active high)</span> |
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| 97 | 00090 <span class="keyword">asm</span> <span class="keyword">volatile</span> (<span class="stringliteral">"nop"</span>); |
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| 98 | 00091 cbi(SRAM_CTRL, SRAM_ALE); <span class="comment">// de-assert ALE (active high)</span> |
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| 99 | 00092 |
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| 100 | 00093 <span class="comment">// switch data bus to input</span> |
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| 101 | 00094 outb(SRAM_ADL_DDR, 0x00); |
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| 102 | 00095 <span class="comment">// clear pullups</span> |
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| 103 | 00096 outb(SRAM_ADL, 0x00); |
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| 104 | 00097 <span class="comment">// request data from memory</span> |
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| 105 | 00098 cbi(SRAM_CTRL, SRAM_RD); <span class="comment">// assert read (active low)</span> |
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| 106 | 00099 <span class="comment">// retrieve data</span> |
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| 107 | 00100 <span class="keyword">asm</span> <span class="keyword">volatile</span> (<span class="stringliteral">"nop"</span>); |
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| 108 | 00101 data = inb(SRAM_ADL_IN); |
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| 109 | 00102 <span class="comment">// release read line</span> |
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| 110 | 00103 sbi(SRAM_CTRL, SRAM_RD); <span class="comment">// de-assert read (active low)</span> |
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| 111 | 00104 <span class="comment">// switch data bus to output</span> |
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| 112 | 00105 outb(SRAM_ADL_DDR, 0xFF); |
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| 113 | 00106 |
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| 114 | 00107 <span class="keywordflow">return</span> data; |
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| 115 | 00108 } |
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| 116 | 00109 |
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| 117 | <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) |
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| 118 | 00111 { |
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| 119 | 00112 outb(SRAM_PAGE, (page & SRAM_PAGE_MASK)); |
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| 120 | 00113 } |
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| 121 | </pre></div><hr size="1"><address style="align: right;"><small>Generated on Sun Oct 29 03:41:07 2006 for Procyon AVRlib by |
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| 123 | <img src="doxygen.png" alt="doxygen" align="middle" border="0"></a> 1.4.2 </small></address> |
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