Simple DIY Logic Converter for 3.3V Devices


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Introduction: Simple DIY Logic Converter for 3.3V Devices

Hobbyist, Electronics Research and Development, Arduino, Raspberry Pi, Linux, Hacking

In this Post, I will show you how you can make your own 5V to 3.3V logic converter for connecting 5V sensors to new Arduino Boards and Raspberry Pi.

Why do we need a Logic Level Converter IC?

Most of you love playing with Arduino and Raspberry Pi during free time right? Of Course that’s what hobbyists do! Along with Arduino, we will definitely use various sensors such as IR sensor, PIR sensor and Ultrasonic sensor. But the problem is most of today’s boards are not 5 V tolerant and almost all of the boards works under 3.3V.

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Step 1: ​74LVC245 Logic Level Converter IC

74LVC245 Logic Level Converter IC

This chip solves the problem of connecting and sending data from 5 V logic level devices to a 3.3 V logic microcontrollers such as Raspberry Pi and Arduino.

This chip stands in between Arduino and the Sensor and converts the 5V signals from the sensor to 3.3V which can be directly fed to Arduino. 74LVC245 can be used with digital signals and works great with SPI, Serial, Parallel bus, and other logic interfaces.

Step 2: Designing the Circuit

You can easily go to EasyEDA website and start a new project. Once you have opened a new canvas, start adding components. For now, JLCPCB have 689 Basic components and 30k+ Extended components at your disposal. See the complete list of components here.

5V to 3.3V logic level converter Circuit diagram Make sure you add the components from this list while drawing the schematics in EasyEDA. You can even search for the components and check its availability. Search for the components from the library and place it in the canvas. Use “Wire” tool to connect the components together.

Working with this IC is pretty simple. You can setup the circuit in a matter of minutes. Simply connect VCC to your logic level you want to convert to. If you are converting 5V to 3.3V, connect 3.3V to VCC. Ground connects to Ground. OE (output enable) to ground to enable the chipDIR to VCC (3.3V).

PCB Layout

Once you have finished drawing the circuit, save the circuit by clicking save and create PCB layout. I will provide links to all the files including the Gerber, Pick n Place and Bill of Material in the description. You can now download the Gerber file and use it to manufacture your PCB from JLCPCB. Gerber File contains information about your PCB such as PCB layout information, Layer information, spacing information, tracks to name a few. Now let us order it.

Step 3: Getting PCBs From JLCPCB

Go to JLC PCBs website and create a free account. Register and Login using Google Account. Once you have successfully created an account, Click on “Quote Now” and upload your Gerber File.

Gerber File contains information about your PCB such as PCB layout information, Layer information, spacing information, tracks to name a few. Once the Gerber file is uploaded, it will show you a preview of your circuit board. Make sure this is the PCB Layout of the board you want. Below the PCB preview, you will see so many options such as PCB Quantity, Texture, Thickness, Color etc.

Choose all that are necessary for you. Now click on “Assemble your PCB boards”. Now, you will have to upload the BOM and CPL file that we downloaded earlier. Select all the components you want JLCPCB to assemble in your PCB.

Simply click on the confirm box to select the components. In this page, you can review your order. You can check the layout, see all the components and if there is any problem, you can click on “Go Back” to edit your order. That’s it guys. Its Done. The PCB will be manufactured and shipped within days and will be delivered to your doorstep within the mentioned time period.

Step 4: Testing

Check Out the Assembled PCBs

This is the assembled board. Neat and Clean.

Once you get the board, you can take one and solder the remaining components into it. I have soldered the header pins and this is the finished board.

These 8 Pins provide steady 5V, these 8 Pins provide 3.3V and these pins are Ground.

Testing Logic Level Converter

Now if you connect the 5 V Signals at A Pins, you will get 3.3 V at corresponding B Pins.

Now we will check that by connecting a 5V in A1 and 0V in A5 So this will gives 3.3V Out at B1 and 0V at B5.

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