I don't know anything about bluetooth devices.

Actually I am connecting TTL Tx, Rx from Bluetooth to RFID module's CMOS Tx, Rx...

Bluetooth is Vdd 3.3V and RFID's is 5V. I am trying with some Voltage translator like MC74VHC1G50DFT1 , but the I can't get any data signal from the RFID module when scanning tag. I only manage to on the RF module, but didn't get any data when it scanned tag. My baudrate is 19.2K

I try to search 'All probe and jig capacitance', but I couldn't understand the meaning, it was mentioned in the datasheet. The Capacitor which connect to GND across the output line.

Any comments if I use pull-up resistor and pull-down resistor to translate the 2 different input/output voltage level?

Anyway, I will be trying with your solution mentioned earlier.

 

Actually I am connecting TTL Tx, Rx from Bluetooth to RFID module's CMOS Tx, Rx...

Bluetooth is Vdd 3.3V and RFID's is 5V. I am trying with some Voltage translator like MC74VHC1G50DFT1 , but the I can't get any data signal from the RFID module when scanning tag. I only manage to on the RF module, but didn't get any data when it scanned tag. My baudrate is 19.2K

I try to search 'All probe and jig capacitance', but I couldn't understand the meaning, it was mentioned in the datasheet. The Capacitor which connect to GND across the output line.

Any comments if I use pull-up resistor and pull-down resistor to translate the 2 different input/output voltage level?

Anyway, I will be trying with your solution mentioned earlier.

As level converter (5V to 3.3v and vice versa) I have found 74HC07 buffer also, because that is a high speed buffer.
Do we need a pull up resistor both for 5V and 3.3V output, since it is open drain output?

 

Connect 3 10K resistors in series and connect one end to ground and the other end to the 5V device then connect the 3.3 V device to the 2nd 10K resistor so that you will have 20K from ground for the 3.3 V device and 30K for the 5 V device.

This voltage devider works pritty well and is what I use normally to interface Xbee module to pics.

Alberto

 

Connect 3 10K resistors in series and connect one end to ground and the other end to the 5V device then connect the 3.3 V

Alberto

Will the resistor network affect the communication speed? my baud rate is 38400bps.

 

Will the resistor network affect the communication speed? my baud rate is 38400bps.

Not at all.

Alberto

 

Hey everyone

So after reading many different posts it’s strange that two conclusions emerge:

1. No one is willing to acknowledge the evident reality
2. No such IC exists that provides translation from 3.3 to 5 in both directions

Am I missing something? If such IC exists it should be powered by ONE supply only, so the objective would be to use that imaginary IC in a 5v design that uses some 3.3v module and the “voltage tolerant” drama doesn’t work.

All the solutions with transistors, inverted logic, pull-ups etc inevitably require an additional voltage regulator to provide the 3.3v.

I don’t mean to re-open an obviously sensitive discussion, just seeking some concrete and credible clarification.