I have two calculators (algebra fx 2.0 plus) which I made communicate by a serial connection RS-232, with the cable RX-TX-GND. I wanted to use a wireless connection, so I bought two XBEE modules
, set the same speed on the calculators and on the XBEE... However, I know that the serial communication of the XBEE is basically 0/3.3V, while my calculator operates with 0/4.2V ... I think the calculator can read the 3.3V as a high logical level (one), but can I take the risk of overpowering the XBEE RX (not the external power) with 4.2V?