Re: LZ: Temperature Sensor
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Edward Plese wrote:
>
> I2C Temperature Sensor
> By: Ed Plese, Jr. (eplese@lnd.com)
>
> Thanks to Per Finander for the basic layout of the schematic and for his
> I2C ASM routines.
>
> The parts needed for the Temperature Sensor are a capacitor, two diodes,
> the IC and half of a link cord. The capacitor can be just about any value
> above 1uF. I have tried 2.2uF, 10uF and 100uF capacitors and they have all
> worked equally well. I would recommend a smaller one (around 2.2uF)
> because I think the larger ones have more of an internal leak so they would
> draw more power from the link port. I wouldn't go much above 100uF because
> then the capacitor will draw a lot of current through the port and possibly
> damage the link port. Also, the smaller you go, the easier it is to buy a
> surface mount one. I plan to make the whole thing a surface mount module
> and maybe it will be small enough to fit inside the calculator. You also
> can use just about any kind of small switching diodes for the two in the
> schematic. I haven't tried any other than the 1N914 type that I used in
> my prototype. The IC is the LM75CIM-5 by National Semiconductor. They can
> be ordered from their web page at www.national.com. For the link cord, I
> used the half of my link that remained from when I made my calculater to
> computer link. In order to make this, you must etch your own PCB or find a
> carrier board for it. For my prototype I just made it so each lead of the
> IC went to a wire. This way I could connect the wires to a breadboard for
> testing. You could either do that or make a PCB and solder everything to
> that. Please note that in the schematics, the chip is upside down with pin
> 1 being in the upper right as opposed to the lower left.
>
> The connections to the chip are as follows:
> 1. SDA (bi-directional data line)
> 2. SCL (serial clock)
> 3. O.S. (no connection in the circuit but has other uses)
> 4. GND
> 5. A2
> 6. A1
> 7. A0
> 8. +Vs
>
> A0-A2 are address bits used for the chips address. In the schematic all of
> these inputs go to GND and are therefore a logical 0. If you want, you can
> change these because the software will allow you to change what one it
> looks for. This also allows you to have multiple temperature sensors on
> the same bus if they are all different. For more information about the
> LM75CIM-5, there is an Acrobat Reader file on their web site that tells ALL
> about it.
>
> The schematics are in the included .GIF file.
>
> If you cannot view this attachment, email me and I'll send you a different
> format.
>
>
>
what are the part needed for the temp. sensor and what code do you have
to run it?
PCoMP
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