8 channel Level Shift

[popeyesfx]

Hi

Just want to confirm how to use the 8 channel shifter with an arduino uno. Am iI right in assuming that I have to connect both the 3.3 volt and the 5v from the arduino to the shift board, then connect the ground to ground, and just match up the data lines like for like. What should I do with the OE connection. Can I use the board with a arduino pro mini, it doesn't have a 3.3v outlet so I am assuming i require a separate 3.3v supply.

cheers

[Franklin97355]

That sounds about right. Don't forget to tie the ground to whatever you are controlling too.

[popeyesfx]

Ok, tie the grounds.
But what about the oe connection, what do i do with that ?

Cheers

[Franklin97355]

According to this document http://www.adafruit.com/datasheets/txb0108appnote.pdf on page 6

Output Enable Control
The TXB devices offer low power consumption of 5-mA maximum ICC when the output enable is high.
When the output enable is low, the TXB translator buffer will be disabled and the outputs are put into a
high impedance state for increased power savings. The OE input circuit is referenced to the VCCA
power-supply and when the device is disabled, the 4-kΩ buffer and the O.S. for both the A-port and B-Port
are also disabled. In this state, output leakage (IOZ) will be less than ±2 mA. If the application does not
require output enable control, The OE pin should be tied to the VCCA supply. One should never leave the
OE pin floating in an indeterminate state as this can cause undesirable quiescent current to flow in the
device, which subsequently increases its overall power dissipation.
Under partial power down conditions, the outputs are also disabled and put into a high-Impedance state.
This feature is referred to as VCC isolation. If VCCB = 0 V, the A-port is disabled. Likewise, if VCCA = 0V, the
B-port will be disabled. In addition, the TXB type translators are fully specified for partial-power-down
applications using the IOFF feature. This IOFF circuitry disables the outputs, preventing damaging current
backflow through the device when these devices are powered-down.
5 Conclusion

I'll check with the other techs to see but I would try it tied through a 1K resistor to both + and ground (not at the same time to see what it does. It may also be tied within the circuit but I couldn't find the schematic. Hold tight and we will get you an answer.

[popeyesfx]

Thanks for the reply.
I will wait for a full reply before doing anything.
Cheers

[adafruit_support_mike]

OE is basically an on/off switch for the output.

If you connect the OE pin to VCCA, the chip will produce output normally. If you connect it to GND, the chip will put all the output pins into high-impedance mode. If you connect it to a GPIO pin, you can control whether the chip produces output or not.

OE pins are useful when you want to have multiple devices connected to the same bus. Pulling one OE pin HIGH and all the others LOW allows you to select the device you want to talk to.

[popeyesfx]

Thanks for the info.
I tested it out and it works great, using it to power a nokia 5110 screen.
cheers