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: 国产精品久久国产三级国不卡顿 | 免费看欧美一级特黄α大片| 一二三四社区在线中文视频| 黄网站在线播放| 老公和他朋友一块上我可以吗| 欧美理伦| 女人张开腿让男人桶免费网站| 美女被羞羞吸乳动漫视频| 国色天香社区在线观看免费播放| 欧美日韩国产精品自在自线| 两个小姨子韩国| 国产热热| 欧美亚洲国产精品久久| а√天堂地址在线| 毛片免费观看网址| 国产在线精品一区二区中文| 精品国产三级在线观看| а√最新版地址在线天堂| 国产欧美日韩在线观看精品| 色婷婷视频| 再深点灬好舒服灬太大了添| 人人爽天天碰天天躁夜夜躁 | 一二三四在线视频社区8| 男女免费爽爽爽在线视频| 好男人社区神马在线观看www| 波多野结衣bd| avav在线播放| 国产自在线观看| 久久亚洲精品国产亚洲老地址| 成年人在线免费观看| 久久国产精品99精品国产| 四虎影视在线观看2022a| chinese男子同性视频twink| 国产深夜福利在线观看网站| 最近中文字幕高清免费大全8| 特级大片| 免费国产不卡午夜福在线| 欧美性理论片在线观看片免费 | 91caoprom| 高清破外女出血视频| 亚洲理论电影在线观看|