{"id":9,"date":"2011-09-17T20:26:22","date_gmt":"2011-09-17T18:26:22","guid":{"rendered":"http:\/\/www.raulet.net\/WP\/?p=9"},"modified":"2011-09-17T22:59:09","modified_gmt":"2011-09-17T20:59:09","slug":"ddr-sdram-i2c-spd","status":"publish","type":"post","link":"https:\/\/www.raulet.net\/WP\/ddr-sdram-i2c-spd\/","title":{"rendered":"DDR SDRAM &#8211; I2C (SPD)"},"content":{"rendered":"<p><a title=\"Origine de l'article\" href=\"http:\/\/www.x86-secret.com\/popups\/articleswindow.php?id=17\" target=\"_blank\">http:\/\/www.x86-secret.com\/popups\/articleswindow.php?id=17<\/a><\/p>\n<p align=\"left\"><span style=\"font-size: medium;\"><strong><span style=\"font-size: large;\">I ) Introduction<\/span><\/strong><\/span><\/p>\n<p align=\"left\">Le SPD ( Serial Presence Detect ), est un composant que l&rsquo;on peut retrouver sur la quasi-totalit\u00e9 des barettes SDRAM actuelles. Ce composant est en fait une EEPROM ( petite m\u00e9moire statique qui ne perd pas les informations qu&rsquo;elle contient au cas de rupture de l&rsquo;alimentation electrique ) contenant l&rsquo;integralit\u00e9 des parametres de la barettes tels que definis par le constructeur. Ainsi, cette petite m\u00e9moire contient des informations tels que les temps d&rsquo;acces de la RAM, la taille de la barettes et une foule d&rsquo;autres param\u00e9tres.<br \/>\nAu boot de la machine, le BIOS consulte le contenu de cette m\u00e9moire afin de configurer les registres du chipset en fonction des informations qui s&rsquo;y trouvent. Le but de la manoeuvres pour nous, amateurs de tweak, est de modifier les valeurs que contient cette m\u00e9moire afin d&rsquo;augmenter les performances de la barette&#8230;Un peu comme quand on passe une barette de CAS 3en CAS 2, mais avec une foule d&rsquo;autres parametres qui sont detaill\u00e9s plus bas&#8230;<\/p>\n<p align=\"left\"><span style=\"font-size: large;\"><strong>II ) EEPROM : Le Composant<\/strong><\/span><\/p>\n<ul>\n<li>\n<div align=\"left\"><span style=\"font-size: small;\"><strong>Pr\u00e9sentation<\/strong><span style=\"font-size: medium;\"><br \/>\n<\/span><\/span><\/div>\n<\/li>\n<\/ul>\n<div align=\"center\">\n<p align=\"left\">Avant toute chose, voyons le composant en lui meme plac\u00e9 sur une barette de SDRAM<\/p>\n<p align=\"center\"><img loading=\"lazy\" decoding=\"async\" src=\"http:\/\/www.x86-secret.com\/pics\/ram\/spd1.jpg\" alt=\"\" width=\"600\" height=\"150\" \/><\/p>\n<\/div>\n<p>Ce composant est donc, comme nous l&rsquo;avons dit plus haut, une m\u00e9moire de type EEPROM s\u00e9rie (<strong>E<\/strong>lectrically\u00a0<strong>E<\/strong>rasable\u00a0<strong>P<\/strong>rogrammable\u00a0<strong>R<\/strong>ead\u00a0<strong>O<\/strong>nly\u00a0<strong>M<\/strong>emory) d&rsquo;une capacit\u00e9 de 2 kbits soit 2048 bits ou 256 octets. Ce composant utilise une interface I2C. Les m\u00e9moires EEPROM S\u00e9rie de 2 Kbits portent g\u00e9n\u00e9ralement comme r\u00e9f\u00e9rence \u00ab\u00a024C02\u00a0\u00bb. Voyons une description et le pinout de ce composant.<\/p>\n<ul>\n<li><strong><span style=\"font-size: medium;\">Fonctionnement<\/span><\/strong><\/li>\n<\/ul>\n<table width=\"100%\" border=\"0\">\n<tbody>\n<tr>\n<td width=\"70%\">Le Boitier utilis\u00e9 est un boitier standard CMS TSSOP8<br \/>\nLes broches 1,2 et 3 permettent de sp\u00e9cifier l&rsquo;adresse du composants ( pour pouvoir interroger le bon module SPD si le systeme comporte plusieurs barettes de m\u00e9moire )<br \/>\nLa broche 4 est la masse du omposant ( ground ou 0V )<br \/>\nLa broche 5 est la broche d&rsquo;entr\u00e9e\/sortie s\u00e9rie des donn\u00e9es (I2C)<br \/>\nLa broche 6 est la broche du signal d&rsquo;horloge (I2C)<br \/>\nLa broche 7 est une broche qui interdit l&rsquo;ecriture dans l&rsquo;EEPROM si elle est mise a la masse ( donc VSS )<br \/>\nLa broche 8 fournit l&rsquo;alimentation au composant ( de 3 \u00e0 6 Volts )<\/td>\n<td width=\"30%\">\n<div align=\"right\"><img loading=\"lazy\" decoding=\"async\" src=\"http:\/\/www.x86-secret.com\/pics\/ram\/tsoip.gif\" alt=\"\" width=\"191\" height=\"113\" \/><\/div>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n","protected":false},"excerpt":{"rendered":"<p>http:\/\/www.x86-secret.com\/popups\/articleswindow.php?id=17 I ) Introduction Le SPD ( Serial Presence Detect ), est un composant que l&rsquo;on peut retrouver sur la [&hellip;]<\/p>\n","protected":false},"author":2,"featured_media":0,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_uag_custom_page_level_css":"","site-sidebar-layout":"default","site-content-layout":"","ast-site-content-layout":"","site-content-style":"default","site-sidebar-style":"default","ast-global-header-display":"","ast-banner-title-visibility":"","ast-main-header-display":"","ast-hfb-above-header-display":"","ast-hfb-below-header-display":"","ast-hfb-mobile-header-display":"","site-post-title":"","ast-breadcrumbs-content":"","ast-featured-img":"","footer-sml-layout":"","theme-transparent-header-meta":"","adv-header-id-meta":"","stick-header-meta":"","header-above-stick-meta":"","header-main-stick-meta":"","header-below-stick-meta":"","astra-migrate-meta-layouts":"default","ast-page-background-enabled":"default","ast-page-background-meta":{"desktop":{"background-color":"var(--ast-global-color-4)","background-image":"","background-repeat":"repeat","background-position":"center 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