30 lines
1.6 KiB
Plaintext
30 lines
1.6 KiB
Plaintext
<!-- { "title": "Integrated Tea Timer and Thermometer, Second Edition" } -->
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<h1>#title#</h1>
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<p>
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I've two offices, so I'm requiring two of this timers.
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</p>
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<p>
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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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</p>
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<p>
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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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</p>
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<p>
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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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</p>
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<p>
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The sources are still available here <s>https://bitbucket.org/wollud1969/teathermotimer</s> <a href="https://gitlab.com/wolutator/TeaThermoTimer/tree/SecondEdition">https://gitlab.com/wolutator/TeaThermoTimer/tree/SecondEdition</a>, look for the branch <code>SecondEdition</code>.
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</p>
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<p>
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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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</p>
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<a href="files/img_0818-e1473677307841.jpg"><img src="files/img_0818-e1473677307841_small.jpg"/></a>
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<a href="files/img_0821-e1473677332189.jpg"><img src="files/img_0821-e1473677332189_small.jpg"/></a>
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