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billy1180
04-08-2007, 04:53 AM
In a previous post I asked how to use the PDN pin of the Parallax transmitter. I used a blocking diode to limit the voltage and everything worked fine...except I wasn't able to pull PDN low and put the transmitter in low power mode. However, with all this talk at UC about powering it down with this pin, why can't I simply connect an I/O pin to the Vdd input on the parallax 27980 transmitter module and control it that way. In other words I would be cutting power to it at will or powering it up as I please. Would this damage the transmitter, the development board or the BS2? I can't imagine why it would as it is not going above 5 Vdc. Any advice would be great. Thank you.

Louis Blessing

Franklin
04-08-2007, 06:32 AM
I'd use a transistor to limit the current draw on the stamp but it should work. Is there any configuration that would be lost by totally powering the transmitter down?

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- Stephen

billy1180
04-08-2007, 07:28 AM
Nope. There would be nothing lost. Also, the project that I am working on doesn't have to be high speed either. It's essentially a sensor network. The reason I thought I'd be able to just connect an I/O pin to the transmitter's vdd pin is that in the basic stamp discovery kit book they connect a 470 ohm resistor to a LED via the Vdd rail on the board of education development board as well as via an I/O pin and the High/Low commands. The book states that the I/O pins switch between high (Vdd) and low (Vss) and that the two configurations are equivalent. Nothing was said about current, but it must be the same as they used the same resistor to limit the current. In any even thanks for the speedy reply and the advice.


Louis