{"id":1174,"date":"2013-10-25T07:33:12","date_gmt":"2013-10-25T07:33:12","guid":{"rendered":"https:\/\/ibex.tech\/resources\/?p=1174"},"modified":"2022-02-18T15:05:17","modified_gmt":"2022-02-18T15:05:17","slug":"i2c-bus-general","status":"publish","type":"post","link":"https:\/\/ibex.tech\/resources\/geek-area\/communications\/i2c\/i2c-bus-general","title":{"rendered":"I2C Bus General"},"content":{"rendered":"<h4>\nI2C Clock Speed<br \/>\n<\/h4>\n<p>\n400kHz&nbsp;means the clock speed for a complete high low clock sequence. &nbsp;So 2.5uS per cycle, 1.25uS per high or low clock edge.\n<\/p>\n<h4>\nPull Up Resistors<br \/>\n<\/h4>\n<p>\nMinimum current that all devices must be able to sink = 3mA\n<\/p>\n<p>\nThis sets the lower resistance limit on the pull-up resistor.\n<\/p>\n<p style=\"margin-left: 40px;\">\n1K7 for a 5V system\n<\/p>\n<p style=\"margin-left: 40px;\">\n1K1 for a 3.3V system\n<\/p>\n<p>\nUsing 2K2 resistors for 5V and 3V3 I2C busses is a common choice.\n<\/p>\n<h4>\nMaximum Capacitance<br \/>\n<\/h4>\n<p>\nThe pull up resistance together with the bus capacitance determines the rise-time of the bus wires. I2C sets a limit of 1 microsecond for the rise time defined between two voltage levels. It can be met in 5V systems if the RC product of the bus pull up resistor and total bus capacitance is less than approx 1.6 microseconds.\n<\/p>\n<h4>\nBus Comms<br \/>\n<\/h4>\n<h5>\n7bit address, receive bytes<br \/>\n<\/h5>\n<p>\n<a href=\"https:\/\/ibex.tech\/resources\/wp-content\/uploads\/sites\/3\/i2c_7bit_rx.png\"><img loading=\"lazy\" decoding=\"async\" alt=\"i2c_7bit_rx\" class=\"alignnone size-medium wp-image-1394\" height=\"29\" src=\"https:\/\/ibex.tech\/resources\/wp-content\/uploads\/sites\/3\/i2c_7bit_rx-300x29.png\" width=\"300\" srcset=\"https:\/\/ibex.tech\/resources\/wp-content\/uploads\/sites\/3\/i2c_7bit_rx-300x29.png 300w, https:\/\/ibex.tech\/resources\/wp-content\/uploads\/sites\/3\/i2c_7bit_rx.png 909w\" sizes=\"auto, (max-width: 300px) 100vw, 300px\" \/><\/a>\n<\/p>\n<h5>\n7bit address, transmit bytes<br \/>\n<\/h5>\n<p>\n<a href=\"https:\/\/ibex.tech\/resources\/wp-content\/uploads\/sites\/3\/i2c_7bit_tx.png\"><img loading=\"lazy\" decoding=\"async\" alt=\"i2c_7bit_tx\" class=\"alignnone size-medium wp-image-1396\" height=\"43\" src=\"https:\/\/ibex.tech\/resources\/wp-content\/uploads\/sites\/3\/i2c_7bit_tx-300x43.png\" width=\"300\" srcset=\"https:\/\/ibex.tech\/resources\/wp-content\/uploads\/sites\/3\/i2c_7bit_tx-300x43.png 300w, https:\/\/ibex.tech\/resources\/wp-content\/uploads\/sites\/3\/i2c_7bit_tx.png 911w\" sizes=\"auto, (max-width: 300px) 100vw, 300px\" \/><\/a>\n<\/p>\n<h5>\nRepeat Start Condition<br \/>\n<\/h5>\n<p>\n<a href=\"https:\/\/ibex.tech\/resources\/wp-content\/uploads\/sites\/3\/i2c_repeat_start.png\"><img loading=\"lazy\" decoding=\"async\" alt=\"i2c_repeat_start\" class=\"alignnone size-medium wp-image-1405\" height=\"88\" src=\"https:\/\/ibex.tech\/resources\/wp-content\/uploads\/sites\/3\/i2c_repeat_start-300x88.png\" width=\"300\" srcset=\"https:\/\/ibex.tech\/resources\/wp-content\/uploads\/sites\/3\/i2c_repeat_start-300x88.png 300w, https:\/\/ibex.tech\/resources\/wp-content\/uploads\/sites\/3\/i2c_repeat_start.png 494w\" sizes=\"auto, (max-width: 300px) 100vw, 300px\" \/>\u200b<\/a>\n<\/p>\n<p>\n&nbsp;\n<\/p>\n<p>\n&nbsp;<\/p>\n","protected":false},"excerpt":{"rendered":"<p>I2C Clock Speed 400kHz&nbsp;means the clock speed for a complete high low clock sequence. &nbsp;So 2.5uS per cycle, 1.25uS per high or low clock edge. Pull Up Resistors Minimum current that all devices must be able to sink = 3mA This sets the lower resistance limit on the pull-up resistor. 1K7 for a 5V system [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[72],"tags":[],"class_list":["post-1174","post","type-post","status-publish","format-standard","hentry","category-i2c"],"_links":{"self":[{"href":"https:\/\/ibex.tech\/resources\/wp-json\/wp\/v2\/posts\/1174","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/ibex.tech\/resources\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/ibex.tech\/resources\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/ibex.tech\/resources\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/ibex.tech\/resources\/wp-json\/wp\/v2\/comments?post=1174"}],"version-history":[{"count":6,"href":"https:\/\/ibex.tech\/resources\/wp-json\/wp\/v2\/posts\/1174\/revisions"}],"predecessor-version":[{"id":1774,"href":"https:\/\/ibex.tech\/resources\/wp-json\/wp\/v2\/posts\/1174\/revisions\/1774"}],"wp:attachment":[{"href":"https:\/\/ibex.tech\/resources\/wp-json\/wp\/v2\/media?parent=1174"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/ibex.tech\/resources\/wp-json\/wp\/v2\/categories?post=1174"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/ibex.tech\/resources\/wp-json\/wp\/v2\/tags?post=1174"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}