Using RSSI pin on #27982 433Mhz Transceiver modules
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I've looked the datasheet for the Parallax #27982 433Mhz Transceiver modules and also at the datasheet from Linx on their LT module but haven't seen any examples on using the RSSI pin. It is supposed to provide an analog voltage out as it relates to the received signal strength. I'd like to find out how much current that pin can safely supply. I'd just like to use it to drive and LED to help with diagnostics. I'll probably have a jumper to enable/disable the LED to save power when not needed. Does anyone know if it will drive a standard RED LED if I use 510ohm resistor in series?
Robert
Robert
Comments
It is not designed to drive an LED. Its output is an analog signal corresponding to the data being received. If you were to hook up the Data line and the RSSI line to a scope you would see that the RSSI somewhat follows the Data line, with the exception of varying with the signal strength. The data line is driven so that it can always generate a 1, so the RSSI at the moment of the Data line going high can tell you the relative signal strength. It could be read with an ADC.
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Chris Savage
Parallax Engineering
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Robert
That depends on what the input voltage range to what you're trying to drive is. You could use a transistor...or you could use an op-amp. At unity gain it would be a buffer and drive the LED directly, if that's what you want to do.
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Chris Savage
Parallax Engineering
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Robert
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Chris Savage
Parallax Engineering
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The LM3914 by itself will not give a good visual indication on a pulsing line. You'll need a sort of sample and hold circuit. Or better yet, just place a 1M resistor and a 0.1uF capacitor across the signal line to ground. That should stabilize the display and give a much more consistent feel to the signal.
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Chris Savage
Parallax Engineering
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