\r\n<?php\r\necho exec('whoami');\r\n?>\r\n<\/code><\/pre>\n\nIt will typcially be 'www-data'. All serial connections, virtual or physical, are owned by the 'dialout' group so if you add www-data to the dialout group your PHP scripts will be able to open\/read\/write the UART (or other serial devices). The following command will add the group to www-data.\n<\/p>\n
\r\n\r\nusermod -a -G dialout www-data\r\n<\/code><\/pre>\n\nYou can confirm this with:\n<\/p>\n
\r\n\r\ngroups www-data\r\n<\/code><\/pre>\n\nYou now need to restart the RPi for the setting to take effect.\n<\/p>\n
\nTransmit A String
\n<\/h4>\n\r\n\r\n<?php\r\n\techo system("echo \\"hello\\" > \/dev\/ttyAMA0 ");\r\n?>\r\n<\/code><\/pre>\n\nInclude this in a php page, load the page using a browser and you should see the data being sent out of the UART TX pin.\n<\/p>\n
\nIf you want to include variables:\n<\/p>\n
\r\n\r\n\t\t\/\/Set baud rate\r\n\t\tsystem("stty -F \/dev\/ttyAMA0 57600");\r\n\t\t\r\n\t\t\/\/Send string including variables\r\n\t\tsystem("sudo echo \\"Hello the value is: " . (string)$some_int_variable . "and also: " . escapeshellarg($some_string_variable) .\t"\\" > \/dev\/ttyAMA0");\r\n<\/code><\/pre>\n\n \n<\/p>\n
\n \n<\/p>\n
\n <\/p>\n","protected":false},"excerpt":{"rendered":"
Turning off the UART functioning as a serial console See the instructions here. Setup Permission You can determine the user PHP is running as with this command in a php page: <?php echo exec('whoami'); ?> It will typcially be 'www-data'. All serial connections, virtual or physical, are owned by the 'dialout' group so if you add www-data to the dialout group your […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[94],"tags":[],"class_list":["post-1855","post","type-post","status-publish","format-standard","hentry","category-uart"],"_links":{"self":[{"href":"https:\/\/raspberry-projects.com\/pi\/wp-json\/wp\/v2\/posts\/1855","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/raspberry-projects.com\/pi\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/raspberry-projects.com\/pi\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/raspberry-projects.com\/pi\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/raspberry-projects.com\/pi\/wp-json\/wp\/v2\/comments?post=1855"}],"version-history":[{"count":4,"href":"https:\/\/raspberry-projects.com\/pi\/wp-json\/wp\/v2\/posts\/1855\/revisions"}],"predecessor-version":[{"id":1877,"href":"https:\/\/raspberry-projects.com\/pi\/wp-json\/wp\/v2\/posts\/1855\/revisions\/1877"}],"wp:attachment":[{"href":"https:\/\/raspberry-projects.com\/pi\/wp-json\/wp\/v2\/media?parent=1855"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/raspberry-projects.com\/pi\/wp-json\/wp\/v2\/categories?post=1855"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/raspberry-projects.com\/pi\/wp-json\/wp\/v2\/tags?post=1855"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}