18 lines
1.8 KiB
HTML
18 lines
1.8 KiB
HTML
define(`TITLE', `Integrated Tea Timer and Thermometer, Second Edition')
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define(`DATE', `2016-09-12')
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define(`CONTENT', `
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I've two offices, so I'm requiring two of this timers.
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The second one I built with a three-digit display and auto-power-down and start with a push-button.
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This thing consumes in operation about 20mA, which is a real lot for so few functionality, but most of the power goes into the display. I was looking for a simple LCD on ebay, but it seems that most of the LCD 7-segment display have only one common and one pin for every single segment instead of one common per digit. These are too many pins for the 2553 and I didn't want to put an additional LCD controller on the board.
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However, when the thing goes in LPM4, it only consumes about 0,1uA, as it is written in the datasheet. Very important to achieve this low power consumption: an input pin requires more power than an output pin put into the right level. And of course the reference generator of the ADC needs to be shutdown.
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The sources are still available here https://bitbucket.org/wollud1969/teathermotimer, look for the branch <code>SecondEdition</code>.
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The schematic is more or less the same, just on digit display more and a reset push-button.
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<a href="http://a385e5.files.wordpress.com/2016/09/img_0818-e1473677307841.jpg" rel="attachment wp-att-730"><img src="http://a385e-5.de/wp-content/uploads/IMG_0818-e1473677307841-768x1024.jpg" alt="img_0818" width="474" height="632" class="alignnone size-large wp-image-730" /></a>
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<a href="http://a385e5.files.wordpress.com/2016/09/img_0821-e1473677332189.jpg" rel="attachment wp-att-731"><img src="http://a385e-5.de/wp-content/uploads/IMG_0821-e1473677332189-1024x768.jpg" alt="img_0821" width="474" height="356" class="alignnone size-large wp-image-731" /></a>
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