> do we have to protect the pin of the PIC if it was driven directly in a
> normal LED flashing app? So I put the device under the sunlight, the
> LED is not currently switched on so there will be a 1.5 on the PICs
> pin (well it's not that much or is it?)

Do you mean the PIC is not powered up but there is voltage on
a pin from the sunlight ?

AIUI the voltage will go through the internal diode to Vcc. 1.5V-
Vdiode isn't enough to start the PIC, but it may affect a re-boot, ie
the PIC can't properly power down and reset. A series resistor
would limit the current available from the LED, but with LF and nW
parts there could still be "issues". It might be that you'd need an
active pass element (FET, 4066 etc) to enable the voltage from the
LED only if the PIC is powered

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