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william chan
09-23-2008, 02:42 AM
Hi,

Can the Stamp 2pe

1. directly read temperature from LM34 temperature sensor?
2. directly control a Infra-red LED to send 1200 baud data to a PC?

Thanks.

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Chris Savage
09-23-2008, 02:53 AM
William,

The answer to your first question is, no, not directly. But with a little support circuitry you could do it. As for number 2, yes. With a properly configured circuit you could send serial data via IR.

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Chris Savage
Parallax Engineering

Phil Pilgrim (PhiPi)
09-23-2008, 03:59 AM
William,

The MoboStamp-pe (http://www.parallax.com/Store/Microcontrollers/BASICStampModules/tabid/134/txtSearch/28300/List/1/ProductID/451/Default.aspx?SortField=ProductName%2cProductName) includes a BS2pe and can read the LM34 directly via its onboard 10-bit ADC (AVR coprocessor). There are two conditions to observe:

1. You don't need readings below 5F. (Lower readings require an auxiliary negative supply and an ADC that can handle negative voltages. Even then, you could get around this limitation by adding a diode to the ground connection of the LM34.)

2. You're not powered from the USB port but are using an external supply with the onboard 5V regulator. (This is because the USB supply can dip as low as 4.3V, and the AVRs use Vdd as a reference for A/D conversions. Alternatively, the AVR can be set to use its internal reference, but you won't get as much dynamic range on the high end unless you divide down the LM34's output.

-Phil