March 5, 2010
about 5 years ago
Hey folks. You’ll notice in the (particularly poor) datasheet that the logic output high and logic output low values are specified with an output current of 10uA. If you are using a 5v supply (which the part requires) then the input impedance to whatever chip you’re trying to read the data from (an MCU or Max232 chip or whatever) needs to be about 500kOhms or more to stay at or under the 10uA specified.
I’ve notice that as the output current from the data pin increases, the bit error rate increases. For those of you having problems achieving more than 2400baud, check the input impedance to your microcontroller pin. If it’s much below 500K? then maybe use a buffer circuit to prevent the output from getting too loaded down.
I have successfully used this module to receive 4800baud NMEA strings from a GPS.
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