{"id":456,"date":"2025-06-01T19:45:19","date_gmt":"2025-06-01T19:45:19","guid":{"rendered":"https:\/\/m1fly.duckdns.org\/?page_id=456"},"modified":"2025-06-21T10:09:06","modified_gmt":"2025-06-21T10:09:06","slug":"pi-stuff","status":"publish","type":"page","link":"https:\/\/m1fly.duckdns.org\/index.php\/pi-stuff\/","title":{"rendered":"Pi Stuff"},"content":{"rendered":"\n

Bus power<\/h2>\n\n\n\n

The pi will limit the power available to your device on the USB bus due to its power limitations. I am using a USB hub and supplying 5v @ 3A. This tells the pi to STFU <\/p>\n\n\n

import os\nos.system(\"echo 1 > \/sys\/bus\/usb\/devices\/1-1.3\/bConfigurationValue\")\nos.system(\"echo 1 > \/sys\/bus\/usb\/devices\/1-1.4\/bConfigurationValue\")\n<\/code><\/pre>\n\n\n\n
Non Serial GPS?<\/h2>\n\n\n\n
I have a Bluetooth  one.<\/p>\n\n\n
#!\/bin\/sh\nsudo rfcomm bind \/dev\/rfcomm0 00:15:4B:01:84:EC\n<\/code><\/pre>\n\n\n\n
Don’t use my mac address use your own! <\/p>\n\n\n\n
WiFi Won’t reconnect<\/h2>\n\n\n\n
Stupid thing,  I put it in my pocket and walked out of WiFi range for a bit.  <\/p>\n\n\n\n
I am back in WiFi range, still no pi. Cron and Script fix…<\/p>\n\n\n
#!\/bin\/bash\n\n#echo \"Script was run @ $(date)\" >>\/var\/log\/wifi_reconnect\n\n# The IP for the server you wish to ping\nSERVER=$(\/sbin\/ip route | awk '\/default\/ { print $3 }')\n\n#echo \"> Server: ${SERVER}\" >>\/var\/log\/wifi_reconnect\n\n# Specify wlan interface\nWLANINTERFACE=wlan0\n\n#echo \"> WLAN Interface: ${WLANINTERFACE}\" >>\/var\/log\/wifi_reconnect\n\n# Send two pings, sending output to \/dev\/null\nping -I ${WLANINTERFACE} -c2 ${SERVER} >\/dev\/null\n\n# If the return code from ping ($?) is not 0 (meaning there was an error)\nif [ $? != 0 ]\nthen\n#echo \"> WiFi no worky. Restart!\" >>\/var\/log\/wifi_reconnect\n# Restart the wireless interface\nip link set wlan0 down\nip link set wlan0 up\n#else\n#echo \"> WiFi works. No restart\" >>\/var\/log\/wifi_reconnect\nfi\n<\/code><\/pre>\n\n\n\n
Unicode Linux<\/h2>\n\n\n\n
To enter a font glyph’s code on Linux,  use a combination of keys and the character’s hexadecimal code. The most common method is Ctrl + Shift + U followed by the hexadecimal code and then pressing Enter<\/mark><\/p>\n\n\n\n
Forgot the time<\/h2>\n\n\n\n
Less than one second<\/h2>\n\n\n\n
Multiple
of a
second<\/th>		Unit<\/th>Symbol<\/th>Definition<\/th>Comparative examples & common units<\/th><\/tr>
10\u221244<\/sup><\/td>Planck time<\/a><\/th>t<\/em>P<\/sub><\/td>Presumed to be the shortest theoretically measurable time interval
(but not necessarily the shortest increment<\/em> of time\u2014see quantum gravity<\/a>)<\/td>		10\u221214<\/sup> qs<\/strong>: The length of one Planck time<\/a> (t<\/em>P<\/sub> = \u210f G \/ c 5 \"{\\displaystyle \u2248 5.39\u00d710\u221244<\/sup> s)[3]<\/a><\/sup> is the briefest physically meaningful span of time. It is the unit of time in the natural units<\/a> system known as Planck units<\/a>.<\/td><\/tr>
10\u221230<\/sup><\/td>quectosecond<\/th>qs<\/td>Quectosecond<\/strong>, (quecto-<\/a><\/em> + second<\/em>), is one nonillionth<\/a> of a second<\/td><\/td><\/tr>
10\u221227<\/sup><\/td>rontosecond<\/th>rs<\/td>Rontosecond<\/strong>, (ronto-<\/a><\/em> + second<\/em>), is one octillionth<\/a> of a second<\/td>300 rs<\/strong>: The mean lifetime<\/a> of W and Z bosons<\/a><\/td><\/tr>
10\u221224<\/sup><\/td>yoctosecond<\/th>ys[4]<\/a><\/sup><\/td>Yoctosecond<\/strong>, (yocto-<\/a><\/em> + second<\/em>), is one septillionth<\/a> of a second<\/td>86 ys<\/strong>: The estimated value on the half-life<\/a> of isotope 5 of hydrogen (hydrogen-5)<\/a>
143 ys<\/strong>: The half-life<\/a> of the nitrogen-10<\/a> isotope of nitrogen
156 ys<\/strong>: The mean lifetime of a Higgs Boson<\/a><\/td><\/tr>
10\u221221<\/sup><\/td>zeptosecond<\/th>zs<\/td>Zeptosecond<\/strong>, (zepto-<\/a><\/em> + second<\/em>), is one sextillionth<\/a> of one second<\/td>1.3 zs<\/strong>: Smallest experimentally controlled time delay in a photon field.[5]<\/a><\/sup>
2 zs<\/strong>: The representative cycle time of gamma ray<\/a> radiation released in the decay of a radioactive atomic nucleus<\/a> (here as 2 MeV<\/a> per emitted photon<\/a>)
4 zs<\/strong>: The cycle time of the zitterbewegung<\/a> of an electron<\/a> ( \u03c9 = 2 m e c 2 \/ \u210f \"{\\displaystyle)
247 zs<\/strong>: The experimentally-measured travel time of a photon across a hydrogen molecule, “for the average bond length of molecular hydrogen”[6]<\/a><\/sup><\/td><\/tr>
10\u221218<\/sup><\/td>attosecond<\/a><\/th>as<\/td>One quintillionth of one second<\/td>12 as<\/strong>: The best timing control of laser pulses.[7]<\/a><\/sup>
43 as<\/strong>: The shortest X-ray laser pulse[8]<\/a><\/sup>
53 as<\/strong>: The shortest electron laser pulse[9]<\/a><\/sup>[10]<\/a><\/sup><\/td><\/tr>
10\u221215<\/sup><\/td>femtosecond<\/a><\/th>fs<\/td>One quadrillionth of one second<\/td>1 fs<\/strong>: The cycle time for ultraviolet light with a wavelength of 300 nanometres<\/a>; the time it takes light to travel a distance of 0.3 micrometres (\u03bcm).
7.58 fs<\/strong>: The period of vibration of a hydrogen molecule.
140 fs<\/strong>: The time needed for electrons to have localized onto individual bromine<\/a> atoms 6 \u00c5ngstrom<\/a> apart after laser dissociation<\/a> of Br2<\/sub>.[11]<\/a><\/sup>
290 fs<\/strong>: The lifetime of a tauon<\/a><\/td><\/tr>
10\u221212<\/sup><\/td>picosecond<\/a><\/th>ps<\/td>One trillionth of one second<\/td>1 ps<\/strong>: The mean lifetime of a bottom quark<\/a>; the time needed for light to travel 0.3 millimetres (mm)
1 ps<\/strong>: The typical lifetime of a transition state<\/a> one machine cycle by an IBM silicon-germanium transistor<\/a>
109 ps<\/strong>: The period of the photon corresponding to<\/a> the hyperfine transition<\/a> of the ground state of cesium-133<\/a>, and one 9,192,631,770th of one second by definition<\/a>
114.6 ps<\/strong>: The time for the fastest overclocked processor as of 2014 to execute one machine cycle.[12]<\/a><\/sup>
696 ps<\/strong>: How much more a second lasts far away from Earth’s gravity due to the effects of general relativity<\/a><\/td><\/tr>
10\u22129<\/sup><\/td>nanosecond<\/a><\/th>ns<\/td>One billionth of one second<\/td>1 ns<\/strong>: The time needed to execute one machine cycle by a 1 GHz microprocessor
1 ns<\/strong>: The time light takes to travel 30 cm (11.811 in)<\/td><\/tr>
10\u22126<\/sup><\/td>microsecond<\/a><\/th>\u03bcs<\/td>One millionth of one second<\/td>1 \u03bcs<\/strong>: The time needed to execute one machine cycle by an Intel 80186 microprocessor
2.2 \u03bcs<\/strong>: The lifetime of a muon<\/a>
4\u201316 \u03bcs<\/strong>: The time needed to execute one machine cycle by a 1960s minicomputer<\/a><\/td><\/tr>
10\u22123<\/sup><\/td>millisecond<\/a><\/th>ms<\/td>One thousandth of one second<\/td>1 ms<\/strong>: The time for a neuron in the human brain to fire one impulse and return to rest[13]<\/a><\/sup>
4\u20138 ms<\/strong>: The typical seek time<\/a> for a computer hard disk
<\/td><\/tr>
10\u22122<\/sup><\/td>centisecond<\/th>cs<\/td>One hundredth of one second<\/td>1.6667 cs<\/strong>: The period of a frame at a frame rate of 60 Hz.
2 cs<\/strong>: The cycle time for European 50 Hz AC electricity 10\u201320 cs<\/strong> (=0.1\u20130.2 s): The human reflex<\/a> response to visual stimuli<\/td><\/tr>
10\u22121<\/sup><\/td>decisecond<\/th>ds<\/td>One tenth of a second<\/td>1\u20134 ds<\/strong> (=0.1\u20130.4 s): The length of a single blink of an eye[14]<\/a><\/sup>
<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n
<\/h2>\n","protected":false},"excerpt":{"rendered":"
Bus power The pi will limit the power available to your device on the USB bus due to its power limitations. I am using a USB hub and supplying 5v @ 3A. This tells the pi to STFU Non Serial GPS? I have a Bluetooth one. Don’t use my mac address use your own! WiFi […]<\/p>\n","protected":false},"author":2,"featured_media":0,"parent":0,"menu_order":0,"comment_status":"closed","ping_status":"closed","template":"","meta":{"footnotes":""},"class_list":["post-456","page","type-page","status-publish","hentry"],"_links":{"self":[{"href":"https:\/\/m1fly.duckdns.org\/index.php\/wp-json\/wp\/v2\/pages\/456","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/m1fly.duckdns.org\/index.php\/wp-json\/wp\/v2\/pages"}],"about":[{"href":"https:\/\/m1fly.duckdns.org\/index.php\/wp-json\/wp\/v2\/types\/page"}],"author":[{"embeddable":true,"href":"https:\/\/m1fly.duckdns.org\/index.php\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/m1fly.duckdns.org\/index.php\/wp-json\/wp\/v2\/comments?post=456"}],"version-history":[{"count":6,"href":"https:\/\/m1fly.duckdns.org\/index.php\/wp-json\/wp\/v2\/pages\/456\/revisions"}],"predecessor-version":[{"id":513,"href":"https:\/\/m1fly.duckdns.org\/index.php\/wp-json\/wp\/v2\/pages\/456\/revisions\/513"}],"wp:attachment":[{"href":"https:\/\/m1fly.duckdns.org\/index.php\/wp-json\/wp\/v2\/media?parent=456"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}