Connect a pic to an rn-41 bluetooth module. I`m not the person who designed the PCB, so I can`t answer exactly why the circuit is the way that it is instead of using the voltage divider used by some other people. Basically, the 5v logic from the pic is used to control transistors which are connected to a 3. 3v source (converting it to
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3. 3v levels). The only issue is that when I connect this to the Rx pin of the rn-41 sparkfun breakout board, suddenly the signal is completely driven to ground (flatline on the o-scope). Is it possible the Rx pin is shorted to ground, or the chip might have been fried Further, on a different setup using a slightly different version of the transistor and a separate bluetooth rn-41 chip (we have two rn-41s) the 3. 3v logic is not driven to ground, and a 3. 3v logic signal is seen on the Rx pin. however the device it is paired with does not receive anything. (I`m not ENTIRELY sure why the max232 is even there. ) ALSO, those aren`t LM-50s. they`re just transistors with the same physical shape. the source is connected to a 3. 3v regulator. the gate is connected to the output of the rs232, and the drain goes to the rx pin of the rn-41 (the chip at the very bottom) note that it has 1 mistake which we already fixed: the max232 chip is not connected to power @ vcc. we fixed that already by soldering a wire from vcc to the nearest inlet connected to power (5v).
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