{"id":1564,"date":"2013-06-17T10:44:36","date_gmt":"2013-06-17T15:44:36","guid":{"rendered":"http:\/\/bardagjy.com\/?p=1564"},"modified":"2013-06-14T13:21:07","modified_gmt":"2013-06-14T18:21:07","slug":"star-point-grounding","status":"publish","type":"post","link":"https:\/\/bardagjy.com\/?p=1564","title":{"rendered":"Star Point Grounding"},"content":{"rendered":"<div id=\"attachment_1570\" style=\"width: 620px\" class=\"wp-caption aligncenter\"><a href=\"http:\/\/bardagjy.com\/wp-content\/uploads\/2013\/06\/2013-05-20-12.01.41.jpg\"><img loading=\"lazy\" decoding=\"async\" aria-describedby=\"caption-attachment-1570\" src=\"http:\/\/bardagjy.com\/wp-content\/uploads\/2013\/06\/2013-05-20-12.01.41-610x316.jpg\" alt=\"Star point grounding in a D-Link managed POE switch.\" width=\"610\" height=\"316\" class=\"size-large wp-image-1570\" srcset=\"https:\/\/bardagjy.com\/wp-content\/uploads\/2013\/06\/2013-05-20-12.01.41-610x316.jpg 610w, https:\/\/bardagjy.com\/wp-content\/uploads\/2013\/06\/2013-05-20-12.01.41-300x155.jpg 300w, https:\/\/bardagjy.com\/wp-content\/uploads\/2013\/06\/2013-05-20-12.01.41-299x155.jpg 299w\" sizes=\"(max-width: 610px) 100vw, 610px\" \/><\/a><p id=\"caption-attachment-1570\" class=\"wp-caption-text\">Star point grounding in a D-Link managed POE switch.<\/p><\/div>\n<p>I was poking around inside a <a href=\"http:\/\/www.dlink.com\/us\/en\/support\/product\/des-1228p-web-smart-24-port-poe-10-100-plus-4-1000base-t-ports-plus-2-combo-ports-switch\">D-Link DES-1228P<\/a> fast ethernet managed power over ethernet (POE) switch. I&#8217;m looking into building a few pieces of equipment that are POE and curious how the &#8220;big boys&#8221; do it. <\/p>\n<p>Opening the device reveals a large main board with several large Marvell ASICs. The large TQFP in the upper right is a Marvell 88E6218, an ARM 9 with 7 switch ports (quick search does not reveal a datasheet). Immediately above the Marvell SoC is RAM and to the right, flash. Next to the flash is what appears to be a JTAG connector. To round out the 24 ports on this switch, a number of <a href=\"http:\/\/www.marvell.com\/switching\/assets\/marvell_linkstreet_88E6092_product_brief.pdf\">Marvell 88E6095<\/a> 8 port managed fast ethernet with three gigabit uplinks.  <\/p>\n<div id=\"attachment_1576\" style=\"width: 620px\" class=\"wp-caption aligncenter\"><a href=\"http:\/\/bardagjy.com\/wp-content\/uploads\/2013\/06\/2013-05-20-11.58.38.jpg\"><img loading=\"lazy\" decoding=\"async\" aria-describedby=\"caption-attachment-1576\" src=\"http:\/\/bardagjy.com\/wp-content\/uploads\/2013\/06\/2013-05-20-11.58.38-610x295.jpg\" alt=\"D-Link DES-122P overview. Power supply upper left, main board, smaller POE board lower middle.\" width=\"610\" height=\"295\" class=\"size-large wp-image-1576\" srcset=\"https:\/\/bardagjy.com\/wp-content\/uploads\/2013\/06\/2013-05-20-11.58.38-610x295.jpg 610w, https:\/\/bardagjy.com\/wp-content\/uploads\/2013\/06\/2013-05-20-11.58.38-300x145.jpg 300w, https:\/\/bardagjy.com\/wp-content\/uploads\/2013\/06\/2013-05-20-11.58.38-299x144.jpg 299w\" sizes=\"(max-width: 610px) 100vw, 610px\" \/><\/a><p id=\"caption-attachment-1576\" class=\"wp-caption-text\">D-Link DES-122P overview. Power supply upper left, main board, smaller POE board lower middle.<\/p><\/div>\n<p>On the upper left is an adequate power supply. On the main board, just below the power connector are two switching power supply modules. Above the main board is a smaller PCB containing what appears to be much of the POE controller hardware. The ribbon cable goes to front panel LEDs and indicators. J4 by the ribbon cable may be a serial port.<\/p>\n<p>All in all it&#8217;s an interesting bit of gear, priced right with useful web and CLI management tools. Just wish it was GigE..<\/p>\n","protected":false},"excerpt":{"rendered":"<p>I was poking around inside a D-Link DES-1228P fast ethernet managed power over ethernet (POE) switch. I&#8217;m looking into building a few pieces of equipment that are POE and curious how the &#8220;big boys&#8221; do it. Opening the device reveals a large main board with several large Marvell ASICs. The large TQFP in the upper [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":1569,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"ngg_post_thumbnail":0,"footnotes":""},"categories":[37],"tags":[124,35,126,125,128,127],"_links":{"self":[{"href":"https:\/\/bardagjy.com\/index.php?rest_route=\/wp\/v2\/posts\/1564"}],"collection":[{"href":"https:\/\/bardagjy.com\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/bardagjy.com\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/bardagjy.com\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/bardagjy.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=1564"}],"version-history":[{"count":24,"href":"https:\/\/bardagjy.com\/index.php?rest_route=\/wp\/v2\/posts\/1564\/revisions"}],"predecessor-version":[{"id":1593,"href":"https:\/\/bardagjy.com\/index.php?rest_route=\/wp\/v2\/posts\/1564\/revisions\/1593"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/bardagjy.com\/index.php?rest_route=\/wp\/v2\/media\/1569"}],"wp:attachment":[{"href":"https:\/\/bardagjy.com\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=1564"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/bardagjy.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=1564"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/bardagjy.com\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=1564"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}