Werner's Miscellanea
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Source at commit a27d1958fb3a238dcdc9fe15e0d0649448409129 created 10 years 2 months ago. By Werner Almesberger, ircstat/ML: update for 12/2013 | |
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1 | <HTML> |
2 | <TITLE> |
3 | Lab Switch |
4 | </TITLE> |
5 | <BODY> |
6 | |
7 | <H1>Lab Switch</H1> |
8 | |
9 | The Lab Switch is a USB-attached device that has a few galvanically |
10 | isolated inputs and output for switching loads and signals in a lab |
11 | environment. |
12 | <P> |
13 | <A href="labsw-0-off.jpg"><IMG src="labsw-0-off-small.jpg"></A> |
14 | <A href="labsw-0-inside.jpg"><IMG src="labsw-0-inside-small.jpg"></A> |
15 | |
16 | <H2>What it can do</H2> |
17 | |
18 | It has two relays to switch loads of several ampere connected to the |
19 | banana jacks on the front panel.<BR> |
20 | There are four independent opto-coupler inputs and outputs at the rear.<BR> |
21 | In parallel to the relays, there are opto-couplers that can be used |
22 | instead if only a low current needs to be switched. |
23 | <P> |
24 | <IMG src="ovr-front.png" align="middle"> |
25 | <IMG src="ovr-rear.png" align="middle"> |
26 | |
27 | |
28 | <H2>Example usage</H2> |
29 | |
30 | The images below show the Lab Switch being used to test how power cycling |
31 | affects a |
32 | <A href="http://milkymist.org/">Milkymist™ One<A>. |
33 | <BR> |
34 | The Lab Switch is inserted into the 5 V DC power supply such that |
35 | it can switch the 5 V supply and ground. |
36 | <BR> |
37 | For further control, the M1 is connected to a PC via the JTAG board. |
38 | <P> |
39 | |
40 | <IMG src="loop-left.png" align="middle"> |
41 | <A href="labsw-m1-off.jpg"><IMG src="labsw-m1-off-small.jpg" align="middle"></A> |
42 | <A href="labsw-m1-boot.jpg"><IMG src="labsw-m1-boot-small.jpg" align="middle"></A> |
43 | <A href="labsw-m1-render.jpg"><IMG src="labsw-m1-render-small.jpg" align="middle"></A> |
44 | <IMG src="loop-right.png" align="middle"> |
45 | <P> |
46 | In the left image, power is turned off. This is indicated by green LEDs |
47 | on both channels. The red main LED indicates that the switch is under |
48 | remote control. |
49 | <BR> |
50 | In the middle image, power has been turned on and the M1 is booting |
51 | into RTEMS and Flickernoise. One can see two small LEDs (appearing |
52 | yellow) in the M1 that indicate this it is powered and booting. |
53 | <BR> |
54 | In the right image, the M1 has booted into Flickernoise and is rendering |
55 | a visual effect. This is also indicated by all three LEDs of the M1 |
56 | being lit. |
57 | <BR> |
58 | A few seconds later, the Lab Switch cuts power and the cycle repeats. |
59 | |
60 | |
61 | <H2>The software</H2> |
62 | |
63 | The firmware is currently extremely simple and just handles toggling |
64 | via the front buttons and direct remote control via USB. |
65 | |
66 | |
67 | <H2>Future work</H2> |
68 | |
69 | The hardware is currently only designed for low "safe to touch" voltages. |
70 | <BR> |
71 | It would be desirable to be able to also switch AC mains and to connect |
72 | inputs or outputs to places that may be at a high potential with respect |
73 | to other inputs and outputs. For this, it will be necessary to make a |
74 | number of modifications to the circuit. Some of them are detailed in |
75 | the |
76 | <A href="http://projects.qi-hardware.com/index.php/p/wernermisc/source/tree/master/labsw/README">README</A>. |
77 | <P> |
78 | In the future, the firmware will be extended to allow the uploading |
79 | of "scripts" that will allow for more complex patterns of interaction. |
80 | <BR> |
81 | For example, instead of using a channel button as a toggle, it could |
82 | switch a device on for a defined interval and then switch it off again. |
83 | |
84 | |
85 | <H2>Sources, mailing list, IRC</H2> |
86 | |
87 | The electrical design, the mechanical design, and the firmware can |
88 | all be found in |
89 | <A href="http://projects.qi-hardware.com/index.php/p/wernermisc/source/tree/master/labsw">the Qi-Hardware git</A>. |
90 | <P> |
91 | Development discussions and such happen on the |
92 | <A href="http://lists.en.qi-hardware.com/mailman/listinfo/discussion"> |
93 | qi-hardware mailing list</A> and on the |
94 | <A href="http://webchat.freenode.net/?randomnick=1&channels=qi-hardware">#qi-hardware |
95 | channel</A> on |
96 | <A href="http://freenode.net/">freenode</A>. |
97 | |
98 | <P> |
99 | <HR> |
100 | Last update: 2011-09-12 <I>Werner Almesberger</I> |
101 | <HR> |
102 | </BODY> |
103 | </HTML> |
104 |
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