# Converting 3.3v logic level to 5v using octal bus transceiver

I'm using the Raspberry PI to communicate with various sensors and other circuits that input and output 5V logic level. The Raspberry Pi itself has 3.3V GPIOs, so i need to convert the logic levels.

I found the following chip, with this capability: http://www.farnell.com/datasheets/1635559.pdf

I'm quite new to hardware development and would like to know if I have to purchase any other components to use this chip. The datasheet mentions pull-up resistors for instance.

I also found this ready to go chip that I think uses the same component. I can see various other components on it, but I would like to use the breadboard version :

Can anyone provide me with a circuit to hook up the SN74LVC245AN safely and effectively on a breadboard.

• Do your GPIOs ever change between input and output? – Ignacio Vazquez-Abrams Nov 1 '13 at 21:01
• Also, the breakout uses a completely different chip. – Ignacio Vazquez-Abrams Nov 1 '13 at 21:03
• During operation I don't intend to change GPIO modes from input to output. I use different GPIO pins for input and output. I do however think I need two of these chips, 3.3v to 5v and vice versa. – Ollusaurus Nov 1 '13 at 21:28
• The '245A won't help you then, since it won't do 3V3 and 5V output at the same time. Look at the '07 or TXB01nn instead. – Ignacio Vazquez-Abrams Nov 1 '13 at 21:31
• As I understood the '245A can do conversion both ways (not at the same time.) I can use two of these chips and get the job done. The main problem is that I don't know what kind of circuit to use with the chips. – Ollusaurus Nov 1 '13 at 21:44

Sparkfun has two logic level translator boards. One is $3.95 and the other$6.95. The cheaper one is based around the TI TXB0104 chip, and has 4 bi-directional channels. I have successfully used this chip in a commercial product where I had to translate back and forth between 3.3v to 1.8v for a cell module.