KL03z LPUART & IrDA Questions

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KL03z LPUART & IrDA Questions

Contributor I



I plan to use 2 KL03z to transfer lpuart serial data between each other, one as a Transmitter and another as a Receiver. Since the KL03z has IrDA capability, I want to experiment with transferring serial data using IR LED from the transmitting KL03z to a photodiode on the receiving KL03z.  

Currently, I'm using the lpuart_non_blocking example from ksdk 1.3 to debug serial communication from PC. Though it seems the lpuart is set in internal loopback mode. How can I change the mode to test loopback using a jumper from Tx to Rx pin?

For IrDA, I would need to know how to change the SIM_SOPT5 to set the Tx pin output to TPM_Ch0 and Rx pin to receive from CMP0.

But there haven't been many examples of an IrDA code for ksdk 1.3, so I'm still unsure how to change the SIM_SOPT5 and the correct TPM or CMP initialization. Can anybody give a pointer?

I am also curious about the part number of the lpuart module that the KL03z uses. To check which voltage level it considers TTL high or low.

I appreciate any help or guidance. Thank you!

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NXP TechSupport
NXP TechSupport

Hi @SantoRy 

As Bob pointed out,  the KSDK is no longer recommend,  you may shift to the MCUxpresso SDK. As much I would like to share a ilustrative example,   unfortunately , we do not have any irDA example using the KL03Z MCUs in our most recent SDK.

Also, there are application demos using the TPM and a ACMP for infrared communication. Altougth they are made for legacy technologies you may check them as a reference.

Using the MCF51EM Family for Infrared Communication

IrDA Driver and SD Card File System on MM/JE Flexis Families

Of course, there are implementations of the irDA for the KE and KM families , however this series of MCUs use a more advance  peripherals like the Flextimer, which  is continuation of the TPM timer.

Implementing infrared functions on UART0 with  FRDM-KE02Z platform.

Regarding your questions

  • You can enable loop test using the  LPUARTx_CTRL [LOOPS] and [RSRC} bits.
  • In the following post, you will find general details of the the application with the same MCU : KL03Z IrDA support 
  • UART pins are digital. So the operation voltage depends on VDD voltage value. The VDD can go up to 3.6v as mentioned in the KL03Z datasheet table 8.  You can check the following post as reference: KL03Z inputs of KL03Z 5V tolerant?


Many apologies for the delay!  I hope this information could help you.

All the best,



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Senior Contributor III

Vishay still makes IrDA modules:


Using a regular IR LED will not have the recommended eye safety technology that the modules have.

The KSDK is no longer recommended in favor of MCUXpresso.
It may have a better example.

I've not used the KL03 so, alas, can't speak the rest of your questions.


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