ter = array_value($config, 'filter');
    $arr = array_value($filter, $type);
    $enable = array_value($arr, 'enable');
    $wordarr = array_value($arr, 'keyword');

    if (0 == $enable || empty($wordarr)) return FALSE;

    foreach ($wordarr as $_keyword) {
        if (!$_keyword) continue;
        $r = strpos(strtolower($keyword), strtolower($_keyword));
        if (FALSE !== $r) {
            $error = $_keyword;
            return TRUE;
        }
    }
    return FALSE;
}

// return http://domain.com OR https://domain.com
function url_prefix()
{
    $http = ((isset($_SERVER['HTTPS']) && 'on' == $_SERVER['HTTPS']) || (isset($_SERVER['HTTP_X_FORWARDED_PROTO']) && $_SERVER['HTTP_X_FORWARDED_PROTO'] == 'https')) ? 'https://' : 'http://';
    return $http . $_SERVER['HTTP_HOST'];
}

// 唯一身份ID
function uniq_id()
{
    return uniqid(substr(md5(microtime(true) . mt_rand(1000, 9999)), 8, 8));
}

// 生成订单号 14位
function trade_no()
{
    $trade_no = str_replace('.', '', microtime(1));
    $strlen = mb_strlen($trade_no, 'UTF-8');
    $strlen = 14 - $strlen;
    $str = '';
    if ($strlen) {
        for ($i = 0; $i <= $strlen; $i++) {
            if ($i < $strlen) $str .= '0';
        }
    }
    return $trade_no . $str;
}

// 生成订单号 16位
function trade_no_16()
{
    $explode = explode(' ', microtime());
    $trade_no = $explode[1] . mb_substr($explode[0], 2, 6, 'UTF-8');
    return $trade_no;
}

// 当前年的天数
function date_year($time = NULL)
{
    $time = intval($time) ? $time : time();
    return date('L', $time) + 365;
}

// 当前年份中的第几天
function date_z($time = NULL)
{
    $time = intval($time) ? $time : time();
    return date('z', $time);
}

// 当前月份中的第几天，没有前导零 1 到 31
function date_j($time = NULL)
{
    $time = intval($time) ? $time : time();
    return date('j', $time);
}

// 当前月份中的第几天，有前导零的2位数字 01 到 31
function date_d($time = NULL)
{
    $time = intval($time) ? $time : time();
    return date('d', $time);
}

// 当前时间为星期中的第几天 数字表示 1表示星期一 到 7表示星期天
function date_w_n($time = NULL)
{
    $time = intval($time) ? $time : time();
    return date('N', $time);
}

// 当前日第几周
function date_d_w($time = NULL)
{
    $time = intval($time) ? $time : time();
    return date('W', $time);
}

// 当前几月 没有前导零1-12
function date_n($time = NULL)
{
    $time = intval($time) ? $time : time();
    return date('n', $time);
}

// 当前月的天数
function date_t($time = NULL)
{
    $time = intval($time) ? $time : time();
    return date('t', $time);
}

// 0 o'clock on the day
function clock_zero()
{
    return strtotime(date('Ymd'));
}

// 24 o'clock on the day
function clock_twenty_four()
{
    return strtotime(date('Ymd')) + 86400;
}

// 8点过期 / expired at 8 a.m.
function eight_expired($time = NULL)
{
    $time = intval($time) ? $time : time();
    // 当前时间大于8点则改为第二天8点过期
    $life = date('G') <= 8 ? (strtotime(date('Ymd')) + 28800 - $time) : clock_twenty_four() - $time + 28800;
    return $life;
}

// 24点过期 / expired at 24 a.m.
function twenty_four_expired($time = NULL)
{
    $time = intval($time) ? $time : time();
    $twenty_four = clock_twenty_four();
    $life = $twenty_four - $time;
    return $life;
}

/**
 * @param $url 提交地址
 * @param string $post POST数组 / 空为GET获取数据 / $post='GET'获取连续跳转最终URL
 * @param string $cookie cookie
 * @param int $timeout 超时
 * @param int $ms 设为1是毫秒
 * @return mixed    返回数据
 */
function https_request($url, $post = '', $cookie = '', $timeout = 30, $ms = 0)
{
    if (empty($url)) return FALSE;

    if (version_compare(PHP_VERSION, '5.2.3', '<')) {
        $ms = 0;
        $timeout = 30;
    }

    is_array($post) and $post = http_build_query($post);

    // 没有安装curl 使用http的形式，支持post
    if (!extension_loaded('curl')) {
        //throw new Exception('server not install CURL');
        if ($post) {
            return https_post($url, $post, $cookie, $timeout);
        } else {
            return http_get($url, $cookie, $timeout);
        }
    }

    is_array($cookie) and $cookie = http_build_query($cookie);
    $curl = curl_init();
    // 返回执行结果，不输出
    curl_setopt($curl, CURLOPT_RETURNTRANSFER, true);
    //php5.5跟php5.6中的CURLOPT_SAFE_UPLOAD的默认值不同
    if (class_exists('\CURLFile')) {
        curl_setopt($curl, CURLOPT_SAFE_UPLOAD, true);
    } else {
        defined('CURLOPT_SAFE_UPLOAD') and curl_setopt($curl, CURLOPT_SAFE_UPLOAD, false);
    }
    // 设定请求的RUL
    curl_setopt($curl, CURLOPT_URL, $url);
    // 设定返回信息中包含响应信息头
    if (ini_get('safe_mode') && ini_get('open_basedir')) {
        // $post参数必须为GET
        if ('GET' == $post) {
            // 安全模式时将头文件的信息作为数据流输出
            curl_setopt($curl, CURLOPT_HEADER, true);
            // 安全模式采用连续抓取
            curl_setopt($curl, CURLOPT_NOBODY, true);
        }
    } else {
        curl_setopt($curl, CURLOPT_HEADER, false);
        // 允许跳转10次
        curl_setopt($curl, CURLOPT_MAXREDIRS, 10);
        // 使用自动跳转，返回最后的Location
        curl_setopt($curl, CURLOPT_FOLLOWLOCATION, true);
    }
    $ua1 = 'Mozilla/5.0 (iPhone; CPU iPhone OS 13_2_3 like Mac OS X) AppleWebKit/605.1.15 (KHTML, like Gecko) Version/13.0.3 Mobile/15E148 Safari/604.1';
    $ua = empty($_SERVER["HTTP_USER_AGENT"]) ? $ua1 : $_SERVER["HTTP_USER_AGENT"];
    curl_setopt($curl, CURLOPT_USERAGENT, $ua);
    // 兼容HTTPS
    if (FALSE !== stripos($url, 'https://')) {
        curl_setopt($curl, CURLOPT_SSL_VERIFYPEER, FALSE);
        curl_setopt($curl, CURLOPT_SSL_VERIFYHOST, FALSE);
        //ssl版本控制
        //curl_setopt($curl, CURLOPT_SSLVERSION, CURL_SSLVERSION_TLSv1);
        curl_setopt($curl, CURLOPT_SSLVERSION, true);
    }

    $header = array('Content-type: application/x-www-form-urlencoded;charset=UTF-8', 'X-Requested-With: XMLHttpRequest');
    $cookie and $header[] = "Cookie: $cookie";
    curl_setopt($curl, CURLOPT_HTTPHEADER, $header);

    if ($post) {
        // POST
        curl_setopt($curl, CURLOPT_POST, true);
        // 自动设置Referer
        curl_setopt($curl, CURLOPT_AUTOREFERER, true);
        curl_setopt($curl, CURLOPT_POSTFIELDS, $post);
    }

    if ($ms) {
        curl_setopt($curl, CURLOPT_NOSIGNAL, true); // 设置毫秒超时
        curl_setopt($curl, CURLOPT_TIMEOUT_MS, intval($timeout)); // 超时毫秒
    } else {
        curl_setopt($curl, CURLOPT_TIMEOUT, intval($timeout)); // 秒超时
    }
    //优先解析 IPv6 超时后IPv4
    //curl_setopt($curl, CURLOPT_IPRESOLVE, CURL_IPRESOLVE_V4);
    curl_setopt($curl, CURLOPT_ENCODING, 'gzip');
    // 返回执行结果
    $output = curl_exec($curl);
    // 有效URL，输出URL非URL页面内容 CURLOPT_RETURNTRANSFER 必须为false
    'GET' == $post and $output = curl_getinfo($curl, CURLINFO_EFFECTIVE_URL);
    curl_close($curl);
    return $output;
}

function save_image($img)
{
    $ch = curl_init();
    // 设定请求的RUL
    curl_setopt($ch, CURLOPT_URL, $img);
    // 设定返回信息中包含响应信息头 启用时会将头文件的信息作为数据流输出
    //curl_setopt($ch, CURLOPT_HEADER, false);
    //curl_setopt($ch, CURLOPT_USERAGENT, $_SERVER["HTTP_USER_AGENT"]);
    // true表示$html,false表示echo $html
    curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
    curl_setopt($ch, CURLOPT_CONNECTTIMEOUT, 10);
    curl_setopt($ch, CURLOPT_SSL_VERIFYHOST, false);
    curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, false);
    //curl_setopt($ch, CURLOPT_BINARYTRANSFER, 1);
    //curl_setopt($ch, CURLOPT_FOLLOWLOCATION, 0);
    curl_setopt($ch, CURLOPT_ENCODING, 'gzip');
    $output = curl_exec($ch);
    curl_close($ch);
    return $output;
}

// 计算字串宽度:剧中对齐(字体大小/字串内容/字体链接/背景宽度/倍数)
function calculate_str_width($size, $str, $font, $width, $multiple = 2)
{
    $box = imagettfbbox($size, 0, $font, $str);
    return ($width - $box[4] - $box[6]) / $multiple;
}

// 搜索目录下的文件 比对文件后缀
function search_directory($path)
{
    if (is_dir($path)) {
        $paths = scandir($path);
        foreach ($paths as $val) {
            $sub_path = $path . '/' . $val;
            if ('.' == $val || '..' == $val) {
                continue;
            } else if (is_dir($sub_path)) {
                //echo '目录名:' . $val . '<br/>';
                search_directory($sub_path);
            } else {
                //echo ' 最底层文件: ' . $path . '/' . $val . ' <hr/>';
                $ext = strtolower(file_ext($sub_path));
                if (in_array($ext, array('php', 'asp', 'jsp', 'cgi', 'exe', 'dll'), TRUE)) {
                    echo '异常文件：' . $sub_path . ' <hr/>';
                }
            }
        }
    }
}

// 一维数组转字符串 $sign待签名字符串 $url为urlencode转码GET参数字符串
function array_to_string($arr, &$sign = '', &$url = '')
{
    if (count($arr) != count($arr, 1)) throw new Exception('Does not support multi-dimensional array to string');

    // 注销签名
    unset($arr['sign']);

    // 排序
    ksort($arr);
    reset($arr);

    // 转字符串做签名
    $url = '';
    $sign = '';
    foreach ($arr as $key => $val) {
        if (empty($val) || is_array($val)) continue;
        $url .= $key . '=' . urlencode($val) . '&';
        $sign .= $key . '=' . $val . '&';
    }
    $url = substr($url, 0, -1);
    $url = htmlspecialchars($url);
    $sign = substr($sign, 0, -1);
}

// 私钥生成签名
function rsa_create_sign($data, $key, $sign_type = 'RSA')
{
    if (!function_exists('openssl_sign')) throw new Exception('OpenSSL extension is not enabled');

    if (!defined('OPENSSL_ALGO_SHA256')) throw new Exception('Only versions above PHP 5.4.8 support SHA256');

    $key = wordwrap($key, 64, "\n", true);
    if (FALSE === $key) throw new Exception('Private Key Error');

    $key = "-----BEGIN RSA PRIVATE KEY-----\n$key\n-----END RSA PRIVATE KEY-----";

    if ('RSA2' == $sign_type) {
        openssl_sign($data, $sign, $key, OPENSSL_ALGO_SHA256);
    } else {
        openssl_sign($data, $sign, $key, OPENSSL_ALGO_SHA1);
    }

    // 加密
    return base64_encode($sign);
}

// 公钥验证签名
function rsa_verify_sign($data, $sign, $key, $sign_type = 'RSA')
{
    $key = wordwrap($key, 64, "\n", true);
    if (FALSE === $key) throw new Exception('Public Key Error');

    $key = "-----BEGIN PUBLIC KEY-----\n$key\n-----END PUBLIC KEY-----";

    // 签名正确返回1 签名不正确返回0 错误-1
    if ('RSA2' == $sign_type) {
        $result = openssl_verify($data, base64_decode($sign), $key, OPENSSL_ALGO_SHA256);
    } else {
        $result = openssl_verify($data, base64_decode($sign), $key, OPENSSL_ALGO_SHA1);
    }

    return $result === 1;
}

// Array to xml array('appid' => 'appid', 'code' => 'success')
function array_to_xml($arr)
{
    if (!is_array($arr) || empty($arr)) throw new Exception('Array Error');

    $xml = "<xml>";
    foreach ($arr as $key => $val) {
        if (is_numeric($val)) {
            $xml .= "<" . $key . ">" . $val . "</" . $key . ">";
        } else {
            $xml .= "<" . $key . "><![CDATA[" . $val . "]]></" . $key . ">";
        }
    }
    $xml .= "</xml>";
    return $xml;
}

// Xml to array
function xml_to_array($xml)
{
    if (!$xml) throw new Exception('XML error');

    $old = libxml_disable_entity_loader(true);

    // xml解析
    $result = (array)simplexml_load_string($xml, null, LIBXML_NOCDATA | LIBXML_COMPACT);
    // 恢复旧值
    if (FALSE === $old) libxml_disable_entity_loader(false);

    return $result;
}

// 逐行读取
function well_import($file)
{
    if ($handle = fopen($file, 'r')) {
        while (!feof($handle)) {
            yield trim(fgets($handle));
        }
        fclose($handle);
    }
}

// 计算总行数
function well_import_total($file, $key = 'well_import_total')
{
    static $cache = array();
    if (isset($cache[$key])) return $cache[$key];
    $count = cache_get($key);
    if (NULL === $count) {
        $count = 0;
        $globs = well_import($file);
        while ($globs->valid()) {
            ++$count;
            $globs->next(); // 指向下一个
        }
        $count and cache_set($key, $count, 300);
    }

    return $cache[$key] = $count;
}

$g_dir_file = FALSE;
function well_search_dir($path)
{
    global $g_dir_file;
    FALSE === $g_dir_file and $g_dir_file = array();
    if (is_dir($path)) {
        $paths = scandir($path);
        foreach ($paths as $val) {
            $sub_path = $path . '/' . $val;
            if ('.' == $val || '..' == $val) {
                continue;
            } else if (is_dir($sub_path)) {
                well_search_dir($sub_path);
            } else {
                $g_dir_file[] = $sub_path;
            }

        }
    }

    return $g_dir_file;
}




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<a href="/IT">编程日记</a><a href="/IT/1731232729a1031531.html" title="首页">FPGA——初识SDRAM</a></div></div></div><div class="main container-w cl"><div class="mainl"><div class="art-post"><div class="title"><h1>FPGA——初识SDRAM</h1><div class="info"><span><a href="/IT"><i class="iconfont icon-crossborder-fill"></i>编程日记</a></span><span><i class="iconfont icon-browse"></i>84</span><span><i class="iconfont icon-message-fill"></i>0</span><span>
                        更新时间：2025-05-10 13:18:49</span></div></div><div class="art-content"><article class="single-post"><div class="entry"><p><p>
<h2>FPGA——初识SDRAM</h2>
<p><strong>SDRAM&#xff08;Synchronous Dynamic Random Access Memory&#xff09;</strong><br /> SDRAM&#xff0c;同步动态随机存储器。同步&#xff0c;工作时钟和fpga系统时钟一致。动态&#xff0c;SDRAM利用电容的存储电荷的特性&#xff0c;但是存储的电荷会慢慢释放&#xff0c;所以SDRAM需要不断的刷新给电容充电。随机&#xff0c;SDRAM不是固定存储的&#xff0c;我们可以把SDRAM当作一个存储阵列。我们可以通过行地址和列地址准确的定位到每一个存储单元&#xff0c;可以指定地址读写。<br /> <strong>一、SDRAM存储容量和速度等级</strong><br /> <br /> 以镁光4Megx16x4Banks 的SDRAM芯片为例<br /> 4Meg :单个bank的存储单元数&#xff08;行列地址乘以列地址数&#xff09;行地址位宽13&#xff0c;列地址位宽9。2的十三次方乘以2的九次方等于 4194304<br /> 16&#xff1a;每个存储单元的比特数&#xff08;位宽&#xff09;<br /> 4banks&#xff1a;bank个数<br /> 总容量&#xff1a;4meg * 16 <em>4 &#61; 4194304</em>16*4<br /> <br /> clock frequency SDRAM能工作的最高时钟频率。<br /> tRCD写入激活命令到开始读写数据所需要的最少等待时间。这里SDRAM的工作时钟&#xff0c;所以等待周期为2。<br /> tRP表示预充电的等待时间&#xff0c;等待周期为2.<br /> tCL为列选通潜伏期&#xff0c;读指令写入到第一个数据有效输出所需的等待时间<br /> <strong>上图中的tRP、tRCD、tCL每个厂家或者不同的SDRAM芯片都不同&#xff0c;可通过配套的书册手册查找。</strong></p> 
<p><strong>二、SDRAM的引脚和操作命令</strong><br /> </p> 
<p>1、<br /> CLK:系统时钟<br /> CKE:时钟使能信号&#xff0c;高电平有效&#xff0c;低电平时 能屏蔽系统时钟&#xff0c;冻结当前的操作。<br /> CS#&#xff1a;片选信号&#xff0c;低电平有效。高电平时屏蔽使能输出端口&#xff0c;除了clk,cke,dqm。<br /> RAS:行选同步信号&#xff0c;低电平时&#xff0c;地址端口A12到A0会输入行地址。<br /> CAS:列选同步信号&#xff0c;低电平时&#xff0c;地址端口输入的列地址。<br /> WE:使能信号&#xff0c;低电平时&#xff0c;能够写操作和预充电。<br /> DQM:数据掩码信号&#xff0c;高电平时&#xff0c;下一个时钟数据总线会出现高阻态。16位的sdram,DQM分为DQM_h,DQM_l,分别控制高八位和第八位。如果全1&#xff0c;则16位全是高阻态。<br /> 20 BA0:bank地址<br /> 21 BA1:bank地址</p> 
<p>A12——A0&#xff1a;地址端口<br /> DQ15——DQ0&#xff1a;数据端口&#xff08;可输入输出&#xff09;<br /> </p> 
<p>2、SDRAM初始化<br /> </p> 
<p>在对SDRAM进行正常的操作之前&#xff0c;SDRAM必须被初始化(预充电&#xff0c;自动刷新&#xff0c;寄存器配置)。<br /> &#xff08;1&#xff09;当SDRAM的 VDD和VDDQ上电&#xff0c;并且时钟稳定后&#xff0c;SDRAM自先得延迟等待100us&#xff0c;在这个等待期间&#xff0c;对于SDRAM只能赋给禁止命令&#xff08;INHIBIT&#xff09;或者空操作(NOP&#xff09;命令。<br /> &#xff08;2&#xff09;100us的延时之后&#xff0c;需要对SDRAM首先执行一次预充电命令&#xff0c;所有的BANK都必须被预充电&#xff0c;以使器件所有的BANK 都处于空闲状态。&#xff08;A10为高电平&#xff09;。<br /> &#xff08;3&#xff09;进入空闲状态后&#xff0c;至少需要执行两个周期的自动刷新命令&#xff0c;自动刷新命令元完成以后&#xff0c;就可以对SDRAM进行加载模式寄存器了&#xff0c;因为模式寄存器上电后处于未知的状态&#xff0c;因此在执行任何的操作命令之前必须加载模式寄存器&#xff0c;在需要的时候&#xff0c;在模式加载完成后可以执行两次自动刷新命令。<br /> <strong>上时序图中的tRP、tRFC、tMRD每个厂家或者不同的SDRAM芯片都不同&#xff0c;可通过配套的书册手册查找。</strong></p> 
<p>3、配置寄存器模式<br /> 通过SDRAM地址总线配置寄存器模式<br /> <br /> A2,A1,A0&#xff1a;突发长度配置<br /> A3&#xff1a;突发类型设置&#xff0c;低电平顺序突发&#xff0c;高电平隔行突发<br /> A4,A5,A6&#xff1a;列选通潜伏期&#xff0c;读命令到到数据出现的时钟周期<br /> A7,A8&#xff1a;工作模式&#xff0c;用户只开放普通模式<br /> A9:写突发模式&#xff0c;低电平读写都采用突发方式&#xff0c;高电平读是突发&#xff0c;写只能写入一个数据<br /> A10,A11,A12:保留位&#xff0c;全部置0</p> 
<p>4、自动刷新<br /> <br /> SDRAM通过刷新操作来保证数据的可靠性。SDRAM的刷新操作是周期性的&#xff0c;目前国际公认的标准是存储电容的保存期上限是64ms&#xff0c;也就是每一行的刷新的循环周期最大是64ms&#xff0c;所以刷新间隔就等于行数/64ms&#xff0c;以字长为13的行地址&#xff0c;64ms/8192&#xff0c;也就是刷新最大间隔等于7812.5ns。<br /> 刷新命令分为两种&#xff0c;一种是自刷新&#xff08;self refresh&#xff09;&#xff0c;一种自动刷新&#xff08;auto refresh&#xff09;。自动刷新需要执行自动刷新操作指令&#xff0c;在此之前需要执行预充电操作。而自刷新是当CKE为低电平时&#xff0c;写入刷新指令&#xff0c;只有当CKE重新拉高时&#xff0c;才会退出自刷新。</p> 
<p>5、写操作&#xff0c;整页突发<br /> <br /> 采用整页突发&#xff0c;页突发长度数值上等于SDRAM一行包含的存储单元个数&#xff0c;可以使用突发终止指令来实现其他长度的写突发操作。当初始化完成且写使能有效时&#xff0c;开始写入写操作指令&#xff0c;同时 BA0-BA1、A0-A12 分别写入 L-Bank 地址、行地址&#xff0c;激活特定 L-Bank 的特定行&#xff0c;激活指令写入后&#xff0c;等待 tRCD时间&#xff0c;此过程中操作命令保持为空操作命令。tRCD等待时间结束后&#xff0c;写入写数据指令&#xff0c;同时 A0-A8 写入待数据的列首地址&#xff0c;读数据指令写入同时&#xff0c;由 DQ 开始写入数据&#xff0c;在最后一个数据写入后的下一个时钟写入突发终止指令。</p> 
<p>6、读操作<br /> <br /> 当初始化完成且读使能有效&#xff0c;发送激活指令到 SDRAM&#xff0c;同时 BA0-BA1、A0-A12 分别写入 L-Bank 地址、行地址&#xff0c;激活特定 L-Bank 的特定行&#xff0c;激活指令写入后&#xff0c;等待 tRCD时间&#xff0c;此过程中操作命令保持为空操作命令。tRCD等待时间结束后&#xff0c;写入读数据指令&#xff0c;同时 A0-A8 写入数据读取首地址&#xff0c;读数据指令写入后&#xff0c;随机跳转到潜伏状态&#xff0c;等待潜伏期结束&#xff0c;DQ 开始输出读取数据&#xff0c;设读取数据个数为 N&#xff0c;自读指令写入周期的下个时钟周期开始计数&#xff0c;N 个时钟周期后&#xff0c;写入突发停止指令&#xff0c;终止数据读操作。</p></div></article></div><div class="info"><div><span>本文发布于:2024-11-10，感谢您对本站的认可！</span></div><div><span>本文链接:</span><a href="http://anandasy.com/IT/1731232729a1031531.html" title="FPGA——初识SDRAM">http://anandasy.com/IT/1731232729a1031531.html</a></div><div><span>版权声明:本站内容均来自互联网，仅供演示用，请勿用于商业和其他非法用途。如果侵犯了您的权益请与我们联系，我们将在24小时内删除。</span></div></div><span class="tag"><i class="iconfont icon-discount" style="font-size:12px;font-weight:bold;opacity:.7;">本文标签：</i><a href="/tag/1028344.html" target="_blank">FPGA初识SDRAM</a></span></div><div class="post_comments" id="comments"><div id="comt-respond" class="commentpost"><h4>发布评论
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