{"id":1773,"date":"2021-06-06T09:34:49","date_gmt":"2021-06-06T08:34:49","guid":{"rendered":"https:\/\/ofalcao.pt\/blog\/?p=1773"},"modified":"2021-06-07T18:09:39","modified_gmt":"2021-06-07T17:09:39","slug":"hot-fingers","status":"publish","type":"post","link":"https:\/\/ofalcao.pt\/blog\/2021\/hot-fingers","title":{"rendered":"Hot fingers"},"content":{"rendered":"<div class=\"seriesmeta\">This post is part 5 of 5 of \u00a0<a href=\"https:\/\/ofalcao.pt\/blog\/series\/lego-bagpiper\" class=\"series-364\" title=\"LEGO bagpiper\">LEGO bagpiper<\/a><\/div>\n<p>I found out that everytime I tested Tuxie McPython the two Technic Hubs were getting hot. Very hot.<\/p>\n\n\n\n<p>Also batteries were draining fast. I hate changing batteries on stationary robots\/automata. For my MINDSTORMS EV3 I tend to use the Li-Ion battery as a PSU, leaving it connected to a 12V\/1.5A wall power adapter.<\/p>\n\n\n\n<p>So I ordered 2x <a href=\"https:\/\/pv-productions.com\/product\/usb-power-box\/\">USB Power Box<\/a> from PV Productions. They fit on the Technic Hub in the place of the 6xAA battery holder and they can withstand 9V\/2A so it seamed a good and clean method.<\/p>\n\n\n\n<p>Less than 3 days after they arrived I melted one \ud83d\ude41<\/p>\n\n\n\n<figure class=\"wp-block-embed is-type-rich is-provider-tumblr wp-block-embed-tumblr\"><div class=\"wp-block-embed__wrapper\">\n<div class=\"tumblr-post\" data-href=\"https:\/\/embed.tumblr.com\/embed\/post\/XYex7bvoF17_RkGj5X9Ebw\/653227609656868864\" data-did=\"77d93a40dd557aa418bd7c53d6d37721aef626fe\"  ><a href=\"https:\/\/cyberxstuff.tumblr.com\/post\/653227609656868864\">https:\/\/cyberxstuff.tumblr.com\/post\/653227609656868864<\/a><\/div><script async src=\"https:\/\/assets.tumblr.com\/post.js\"><\/script>\n<\/div><\/figure>\n\n\n\n<p>The 4 Large Angular motors were consuming too much current. To proper close the holes I was forcing the motors to strongly press the fingers against the chanter but never thought that would require 2A (probably even more).<\/p>\n\n\n\n<p>So I changed the code to reduce the fingers strength and opted for other fingertips also made with protective foam but a different one, apparently less &#8220;foamy&#8221; and a bit thinner. I glued over the EVA foam fingertips I already tried before and cut them a bit larger so the hole would get more covered (no fotos but can be seen used on last video).<\/p>\n\n\n\n<p>Even so, rechargeable NiMH batteries were still draining too fast (and the hubs were still getting hot). So I picked some alligator cables and 2.1 mm barrel adapters and used 2 of my wall power adapters to power the Hubs. I set them for 9V (measured 9.1 with no load) and connected them &#8211; it worked:<\/p>\n\n\n\n<figure class=\"wp-block-embed is-type-rich is-provider-tumblr wp-block-embed-tumblr\"><div class=\"wp-block-embed__wrapper\">\n<div class=\"tumblr-post\" data-href=\"https:\/\/embed.tumblr.com\/embed\/post\/XYex7bvoF17_RkGj5X9Ebw\/652711342437023744\" data-did=\"56810e7c15df75fddffbc83e968fb1c6d7100c52\"  ><a href=\"https:\/\/cyberxstuff.tumblr.com\/post\/652711342437023744\">https:\/\/cyberxstuff.tumblr.com\/post\/652711342437023744<\/a><\/div><script async src=\"https:\/\/assets.tumblr.com\/post.js\"><\/script>\n<\/div><\/figure>\n\n\n\n<p>but while playing I got a blinking LED and very often one of the hubs just powered off. The adapters are rated 1.5A&#8230; so the motors were still demanding too much current.<\/p>\n\n\n\n<p>As I said before&#8230; I don&#8217;t have other proper motors &#8211; the smaller version of this motors, sold with the 51515 Robot Inventor, are not easy to find and it would be very expensive to buy 8 of them on Bricklink. I could use the BOOST external motors but I don&#8217;t have 8 of them and I am not so sure they have enough power to properly close the holes. Same for Technic motors (except maybe the larger ones) and none of them have internal zero reference (not a major blocker but its something that helps).<\/p>\n\n\n\n<p>So I have 8 motors that demand too much current and two hubs that get too hot and shutdown&#8230; I have no other proper motors&#8230; but I do have other two identical hubs.<\/p>\n\n\n\n<p>So last version of Tuxie McPython now uses 4 Technic Hubs, each controlling two fingers. Code is essentially the same, just less &#8220;if&#8230;then&#8230;elif&#8221; and a shorter &#8220;command vocabulary&#8221;:<\/p>\n\n\n\n<pre class=\"wp-block-preformatted\">   G = ['0', '0', '0', '0'] # 00 00 00 00\n   A = ['0', '0', '0', '1'] # 00 00 00 01\n   B = ['0', '0', '0', '3'] # 00 00 00 11\n   C = ['0', '0', '1', '2'] # 00 00 01 10\n   D = ['0', '0', '3', '2'] # 00 00 11 10\n   E = ['0', '1', '0', '1'] # 00 01 00 01\n   F = ['0', '3', '0', '1'] # 00 11 00 01\nHi_G = ['1', '3', '0', '1'] # 01 11 00 01\nHi_A = ['3', '2', '0', '1'] # 11 10 00 01<\/pre>\n\n\n\n<p>So I now send just 4 different commands (&#8216;0&#8217;, &#8216;1&#8217;, &#8216;2&#8217; or &#8216;3&#8217;) to each hub instead of previous 16 but from the controller side have to send those messages to 4 hubs instead of just 2. My only concern was that my laptop couldn&#8217;t proper handle 4 simultaneous BLE sessions but thankfully it works fine.<\/p>\n\n\n\n<p>With 2 motors per hub I can now use NiMH batteries without blinking LEDs. The hubs still get hot (not so hot as before but still very warm) and the batteries will probably run down after a few songs but for that I already ordered 9V\/2A power adapters and more alligator cables.<\/p>\n","protected":false},"excerpt":{"rendered":"<div class=\"seriesmeta\">This post is part 5  of 5 of \u00a0<a href=\"https:\/\/ofalcao.pt\/blog\/series\/lego-bagpiper\" class=\"series-364\" title=\"LEGO bagpiper\">LEGO bagpiper<\/a><\/div><p>I found out that everytime I tested Tuxie McPython the two Technic Hubs were getting hot. Very hot. Also batteries were draining fast. I hate changing batteries on stationary robots\/automata. For my MINDSTORMS EV3 I tend to use the Li-Ion battery as a PSU, leaving it connected to a 12V\/1.5A wall power adapter. So I &hellip; <a href=\"https:\/\/ofalcao.pt\/blog\/2021\/hot-fingers\" class=\"more-link\">Continuar a ler<span class=\"screen-reader-text\"> &#8220;Hot fingers&#8221;<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_jetpack_memberships_contains_paid_content":false,"footnotes":"","jetpack_publicize_message":"","jetpack_publicize_feature_enabled":true,"jetpack_social_post_already_shared":true,"jetpack_social_options":{"image_generator_settings":{"template":"highway","enabled":false},"version":2}},"categories":[1],"tags":[],"series":[364],"class_list":["post-1773","post","type-post","status-publish","format-standard","hentry","category-sem-categoria","series-lego-bagpiper"],"jetpack_publicize_connections":[],"jetpack_featured_media_url":"","jetpack_sharing_enabled":true,"jetpack_shortlink":"https:\/\/wp.me\/p2Mhyv-sB","_links":{"self":[{"href":"https:\/\/ofalcao.pt\/blog\/wp-json\/wp\/v2\/posts\/1773","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/ofalcao.pt\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/ofalcao.pt\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/ofalcao.pt\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/ofalcao.pt\/blog\/wp-json\/wp\/v2\/comments?post=1773"}],"version-history":[{"count":0,"href":"https:\/\/ofalcao.pt\/blog\/wp-json\/wp\/v2\/posts\/1773\/revisions"}],"wp:attachment":[{"href":"https:\/\/ofalcao.pt\/blog\/wp-json\/wp\/v2\/media?parent=1773"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/ofalcao.pt\/blog\/wp-json\/wp\/v2\/categories?post=1773"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/ofalcao.pt\/blog\/wp-json\/wp\/v2\/tags?post=1773"},{"taxonomy":"series","embeddable":true,"href":"https:\/\/ofalcao.pt\/blog\/wp-json\/wp\/v2\/series?post=1773"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}