Operating KW36 with a 26MHz XTAL

Document created by Luis Antonio Burgos Lopez Employee on Oct 1, 2018
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By default, FRDM-KW36 board includes a 32MHz XTAL (YI) as shown in Figure 1 but there are cases where a 26MHz XTAL is needed instead of 32MHz XTAL for FRDM-KW36 or a custom KW36 board.

 

Y1

Figure 1. 32MHz XTAL from FRDM-KW36 schematics

 

Wireless connectivity demos from FRDM-KW36 Sofware Development Kit are configured to run with a 32MHz XTAL by default, but it's very easy to modify the software to operate with a 26MHz XTAL.

 

Follow next steps to configure a FRDM-KW36 wireless connectivity demo to operate with a 26MHz XTAL:

 

1. In clock_config.h file, change BOARD_XTAL0_CLK_HZ define from 32000000U to 26000000U as shown in Figure 2.

 

Figure 2. BOARD_XTAL0_CLK_HZ define in clock_config.h

 

 

2. Add RF_OSC_26MHZ=1 line in preprocessor:

 

If using IAR IDE:

  • Right click on your project, then click options (Figure 3).

Figure 3. IAR project options

 

  • Go to C/C++ Compiler tab, then Preprocessor, and add RF_OSC_26MHZ=1 line in defined symbols window (Figure 4).

 

Figure 4. IAR Preprocessor

 

If using MCUXpresso IDE:

 

  • Right click on your project, select Properties, go to Settings under C/C++ Build, then Preprocessor under MCU C Compiler (Figure 5).

 

Figure 5. MCUXpresso Preprocessor

 

  • Click on add button from Defined symbols, write RF_OSC_26MHZ=1 and click OK to finish (Figure 6).

 

Figure 6. MCUXpresso Defined symbols

 

To finish, re-compile your project and it will be ready to operate with a 26MHz XTAL.

 

FRDM-KW36 SDK can be downloaded from the MCUXpresso webpage.

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