手机看片福利永久国产日韩-手机看片369-手机精品在线-手机国产乱子伦精品视频-国产精品嫩草影院在线观看免费-国产精品嫩草影院在线播放

首頁 新聞 > 科技 > 正文

用VHDL設(shè)計的任意頻率分頻器

Sometimes I need to generate a clock at a lower frequency than the main clock driving the FPGA. If the ratio of the frequencies is a power of 2, the logic is easy. If the ratio is an integer N, then a divide-by-N counter is only a little harder. But if the ratio isn"t an integer, a little (and I mean a little) math is required. Note that the new clock will have lots of jitter: there"s no escaping that. But it will have no drift, and for some applications that"s what counts. If you have a clock A at frequency a, and want to make a clock B at some lower frequency b (that is, b a), then something like: d = 0; forever { Wait for clock A. if (d 1) { d += (b/a); } else { d += (b/a) - 1; /* getting here means tick for clock B */ } } but comparison against zero is easier, so subtract 1 from d: d = 0; forever { Wait for clock A. if (d 0) { d += (b/a); } else { d += (b/a) - 1; /* getting here means tick for clock B */ } } want an integer representation, so multiply everything by a: d = 0; forever { Wait for clock A. if (d 0) { d += b; } else { d += b - a; /* getting here means tick for clock B */ } } For example. I just bought a bargain batch of 14.1523MHz oscillators from BG but I need to generate a 24Hz clock. So a=14152300 and b=24: d = 0; forever { Wait for clock A. if (d 0) { d += 24; } else { d += 24 - 14152300; /* getting here means tick for clock B */ } } For a hardware implementation I need to know how many bits are needed for d: here it"s 24 bits to hold the largest value (-14152300) plus one more bit for the sign. In VHDL this looks like: signal d, dInc, dN : std_logic_vector(24 downto 0); process (d) begin if (d(24) = "1") then dInc = 0000000000000000000011000; -- (24) else dInc = 1001010000000110110101100; -- (24 - 14152300) end if; end process; dN = d + dInc; process begin wait until A"event and A = "1"; d = dN; -- clock B tick whenever d(24) is zero end process;

關(guān)鍵詞: VHDL任意頻率分頻器

最近更新

關(guān)于本站 管理團隊 版權(quán)申明 網(wǎng)站地圖 聯(lián)系合作 招聘信息

Copyright © 2005-2018 創(chuàng)投網(wǎng) - www.extremexp.net All rights reserved
聯(lián)系我們:33 92 950@qq.com
豫ICP備2020035879號-12

 

主站蜘蛛池模板: 中日韩国语视频在线观看| 久久九色综合九色99伊人| 中文字幕免费在线观看动作大片| 国产一区二区精品| 自拍欧美亚洲| 日韩中文精品亚洲第三区| 2021国产麻豆剧果冻传媒电影| 天天爱夜夜操| 野花日本中文版免费观看| 波多野结衣在线看片| 中文字字幕在线精品乱码app | 日韩插插插| 中文字幕影片免费在线观看| 在线va| 好妻子韩国片在线| 一级成人理伦片| 久久精品a亚洲国产v高清不卡 | 免费又黄又爽1000禁片| 打开腿我想亲亲你下面视频| 欧美成人怡红院在线观看| v片免费在线观看| 激情小说第一页| 国产特级毛片aaaaaa毛片| 天天做天天摸天天爽天天爱| 含羞草实验室入口免费网站直接| 日本特黄特色aa大片免费| 天天射天天操天天| 最近免费中文字幕大全| jizz日本在线观看| 日韩欧美在线观看视频| 一本热久久sm色国产| 麻豆视传媒一区二区三区| 韩国三级hd中文字幕| 亚洲成a人片在线观看中文| 三级伦理在线| 黄网站色视频免费观看| 337p中国人体啪啪| 工囗番漫画全彩无遮挡| 国产精品美女www爽爽爽视频| 老师让我她我爽了好久动漫| 女bbbbxxxx另类亚洲|