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: 欧美色欧美亚洲高清在线观看| 超碰8| 奶特别大的三级日本电影| 国产综合精品| 国内精品久久久久影院蜜芽| 99久久国产综合精品麻豆 | 男女无遮挡边做边吃视频免费| 精品毛片视频| 日韩高清在线不卡| 台湾三级香港三级经典三在线| 欧美美女一区| 旧里番洗濯屋1一2集无删减| 免费91麻豆精品国产自产在线观看| 欧美在线播放| 国内精品伊人久久久影视| 亚洲欧美国产精品第1页| а√天堂地址在线| 尹人久久大香找蕉综合影院| 精品久久久久久中文字幕| gogogo高清在线播放| 亚洲人成电影院在线观看| 村上里沙在线播放| 女让张开腿让男人桶视频| 国产福利在线观看一区二区| 四虎1515hh丶com| 久久在精品线影院精品国产| 鲁一鲁射一射| 无翼少无翼恶女漫画全彩app| 日韩毛片| 538免费视频| 免费无遮挡肉动漫在线观看| 国内精品久久久久影院免费 | 夫醉酒被公侵犯的电影中字版 | 67194在线看片| 最近高清中文字幕在线国语5| 日本黄免费| aaa毛片免费观看| 一级做a爱过程免费视| 日韩毛片高清在线看| 两个人看的www视频免费完整版 | 99久久精品免费看国产|