COM3 Voltage 5V to 3V

Started by ap0c...@gmail.com August 22, 2007
I have configured 2 pins for com3 to communicate with a Siemens C35 using its RX,TX pins so far so good i can communicate with the cellphone, but in order to the cellphone don't loose its network signal the voltage in the RX pin must be limited to 3V to communicate with correctly and without the phone loose its network signal.

How can i make the voltage come down from 5v(comp3 RX) to 3V(cellphone TX)? i was thinking of using a MAX3232 between the two com3 pins and the cellphone in order to convert the 5v in 3v should this work? or are any easier way?
On Wednesday 22 August 2007 05:58, a...@gmail.com wrote:
> I have configured 2 pins for com3 to communicate with a Siemens C35 using
> its RX,TX pins so far so good i can communicate with the cellphone, but in
> order to the cellphone don't loose its network signal the voltage in the RX
> pin must be limited to 3V to communicate with correctly and without the
> phone loose its network signal.
>
> How can i make the voltage come down from 5v(comp3 RX) to 3V(cellphone TX)?
> i was thinking of using a MAX3232 between the two com3 pins and the
> cellphone in order to convert the 5v in 3v should this work? or are any
> easier way?
I figured it out, solved the problem doing a voltage divider with a 12K
resistor between basic TX and cellphone RX and another 18K resistor between
cellphone RX and GND.

Thnks anyway :)

--
Pedro Dias
a...@gmail.com
http://alumni.ipt.pt/~pmad/