Updating the S32K144EVB to Switch between 5V and 3.3V Logic Levels

By default, the NXP S32K144EVB and microcontroller is using a 5V supply voltage and logic levels which is great for noisy environment or any 5V devices. Many of my displays and sensors use 3.3V logic levels, so I would have to use a level shifter from 5V to 3.3V. There is another way: to change the board for 3.3V logic levels so I can use directly things like a SSD1306 display.

S32K144EVB with OLED SSD1306 using 3.3V Logic Levels

S32K144EVB with OLED SSD1306 using 3.3V Logic Levels

The board schematic overview shows a VDD selection:

S32K144 EVB VDD Selection

S32K144 EVB VDD Selection

In the schematics this is implemented as shown below:

S32K144EVB power Supply Selection

S32K144EVB power Supply Selection

With the R64 (0 Ohm resistor) the board is hard-wired to use 5V (P5V0 to VDD which is the CPU supply voltage). So all what I would need is to remove R64 and install a jumper on J10 to switch between 5V and 3.3V.

Removing R64 is easy with SMD de-solder tweezers tips.

Desoldering tweezer tips

Desoldering tweezer tips

But the through holes for J10 are filled with solder, it seems the board manufacturing data used the wrong solder mask :-(.

Filled holes for J10

Filled holes for J10

Weller Desoldering Station

Weller Desoldering Station

After painfully removing the solder from HDR J10, I was able to install a 3-pin header:

Removed R64 and added J10 on S32K144EVB

Removed R64 and added J10 on S32K144EVB

With a jumper on 1-2 I have no 3.3V:

S32K144EVB J10 Jumper position for 3.3V VDD

S32K144EVB J10 Jumper place for 3.3V VDD

Another solution would have been to use a solder bridge between 1-2, but having a jumper is a much nicer way, and I can revert back to 5V VDD if I have to.

Happy Leveling 🙂

PS: that project for the SSD1306 OLED display is available on GitHub.

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3 thoughts on “Updating the S32K144EVB to Switch between 5V and 3.3V Logic Levels

    • Hi Juan,
      no, the K64F is a 3.3V microcontroller and cannot be used with 5V. Some Kinetis have ‘5V capable pins’, but I never have used that, as only a few pins implement this. I rather use a 5V CPU or a level shifter if needed.

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