Jan 27, 2015 - 07:58 AM I want to use a 74LVC245 as a logic level shifter to interface a 3.3v device with an Arduino Uno. Vcc for the 74LVC245 will be 3.3v. Vcc for the Atmega328 on the Arduino is 5v. As far as I know, the Atmega328, when powered at 5v can read inputs as logic high as long as they are above .6*Vcc=3v. Nearby, I wondered if it would be good to have a sticky thread about the various possible approaches, and the pitfalls, in interfacing 5V devices with modern 3V3 devices. 74LVC245 - Breadboard Friendly 8-bit Logic Level Shifter- The Pi Hut Most of our customers love using the Arduino for prototyping, design and invention but find themselves stuck when trying to connect the Arduino to the latest sensors, displays, controllers, interfaces, etc. as they are almost all 3.3V logic these days. Connect the third pin SD ChipSelect of the OLED (gray wire) to pin #18 of the 74LVC245. Then connect pin #2 of the 74LVC245 to Arduino Digital #4. This is the pin to select that we want to talk to the microSD card. Then connect second-from-the bottom pin of the OLED - SDOUT - with a wire directly to Arduino Digital #12 this is the longer white wire if they are readily available in DIP. 74LVC245 gives you 8 buffers from 5V → 3.3V, but can't map the other way (though you don't normally need to, Arduinos should read 3.3V as HIGH). I want it to interface Arduino with SD cards, accelerometers and such stuff, using soething "better" than just a resistor divider. What are the bes solutions? Regards 1 We are using the 4-channel bidirectional TXS0104E in a commercial product, and it is working very well for us. In our case it is being used to convert from 3.3v to 1.8v and vice versa, but it can also be used to convert from 5v to 3.3v and vice versa (actually the high side can be anywhere from 2.3v to 5.5v, and the low side from 1.65v to 3.6v). Adafruit 74LVC245 - Breadboard Friendly 8-bit Logic Level Shifter [ADA735] Brand: Adafruit. 4.5 out of 5 stars. 5 ratings. Price: $6.49 Get Fast, Free Shipping with Amazon Prime & FREE Returns. Return this item for free. Free returns are available for the shipping address you chose. You can return the item for any reason in new and unused Our tutorial, wiring and example code is all for SPI so if you need 8-bit, check the datasheets for OLED CS Pin - purple wire - 74LVC245 pin #17 OLED Reset Pin - blue wire - 74LVC245 pin #16 OLED D/C Pin - yellow wire - 74LVC245 pin #15 OLED SCLK Pin - orange wire - 74LVC245 pin #14 Adafruit Industries, Unique & fun DIY electronics and kits 74AHCT125 - Quad Level-Shifter (3V to 5V) [74AHCT125] : ID 1787 - Level shifting chips let you connect 3V and 5V devices together safely. This chip is similar to others in the shop (such as the 74LVC125) except this one is particularly good at converting 3V logic up to 5V. This is in demand, especially when connecting some 3V devices 11,248 Apr 17, 2011 #2 The output high voltage of a high speed Cmos 74HCT245 is 5.0V. The output high voltage of a TTL 74LS245 is only about 2.7V to 3.5V. The IC it drives might need a minimum input high voltage of 3.5V, look it up. nomurphy Joined Aug 8, 2005 567 Apr 18, 2011 #3 The 'T" in HCT means TTL compatible. C Thread Starter CVMichael Description IC, 74LVC245 8-BIT LOGIC LEVEL SHIFTER Frequently bought together 8 CHANNEL BI-DIRECTIONAL LOGIC LEVEL SHIFTER CONVERTER CA$11.50 IC REGULATOR 7805 +5V 1A CA$1.00 EACH PAR38 120V 5W E26 ECOBRITE-LED CA$18.00 EACH FLAT RIBBON JUMPER CABLE 40 PIN F/F 210MM CA$5.50 EACH F