Has anyone ever used the TXB0101 level shifting IC's to interface between an Arduino and Telit GE865? I serially connecting through a TXB0101 (single channel bidirectional logic level shifter) and a TXB0106 (six channel) and for some reason the communication from the Telit (2.8v) to the Arduino (5v) is extremely noisy...to the point that the data is garbled. The Arduino(5v) Tx to Telit (2.8v) is very clean but as soon as I connect the other signal it all goes to hell. I was originally using the Sparkfun logic level breakout pcbs which worked well but I wanted to try the other IC's because they have an OE that I would like have controll over to HiZ the serial port. Should I be using pull up resistors maybe? Any help would be appreciated.
Yup. If I use the sparkfun logic level converter for Rx and Tx it works beautifully. If I take the Tx (referencing Arduino) and pipe it through the TXB (tried multiple chips) and the Rx on the sparkfun converter it works beautifully (all signals look perfectly clean on the scope). When I put the Tx back on the sparkfun board and move the Rx to the TXB the signal is extremely noisy (to the point it won't read it) but the Tx signal still looks clean. I'm stumped....
Thanks Mike...I have a question about this for you (sorry my basic electronics is very rusty)...Is the pull resistor going to increase the current to the TXB? I just finished reading over the TXB and Telit data sheets and it looks like the Telit 2.8 volt logic only supplies about 1 mA and the TXB needs 2 mA...what do you think? Thanks again for all the help.