5 years, 1 month ago.

FRDM-K64F USART Transmit Voltage

I am thinking about using a Wifi Module (ESP8266) and connecting it to my FRDM-K64F. However the Wifi Module pin needs to receive 3.3v over the USART. I looked at the information regarding my platform, however I could not find the voltage level that my micro-controller uses for USART. Could someone tell me what the USART voltage level is? If it is 5v, then I will use a voltage divider.


1 Answer

5 years, 1 month ago.


According to the K64P144M120SF5 datasheet (K64F), the table on page 6 states that all DIO pins have a maximum input voltage range of -0.3V to +5.5V. So, your ESP8266 output signal should be ok. Not every MPU can tolerate 5V on their input pins. I'm glad that Freescale took that into account.

The K64F output will be from 0 to 3.3V so, your ESP8266 should be ok with that too.