View source for How to enable trace feature on i.MX RT

{{PageHeader|How to enable trace feature on i.MX RT}}

By default, trace pins are configured as GPIO.
To use trace functionality, it is necessary to configure pinmux and enable clock to trace unit.
This operation has to be done as early as possibly in init code.

Best way is to use ''SystemInitHook'' function, which is called in early init steps.
By default, there is an empty ''SystemInitHook'' defined in CMSIS files, with ''__weak__'' linking attribute.
If linker finds ''SystemInitHook'' in any user files it will be used instead of default one.

So, to enable trace support, we need to define following function in any *.c file:

 void SystemInitHook (void)
 {
    // configure trace port
    // configure pinmux
    IOMUXC_SetPinMux(IOMUXC_GPIO_B0_04_ARM_CM7_TRACE00, 0U);
    IOMUXC_SetPinMux(IOMUXC_GPIO_B0_05_ARM_CM7_TRACE01, 0U);
    IOMUXC_SetPinMux(IOMUXC_GPIO_B0_06_ARM_CM7_TRACE02, 0U);
    IOMUXC_SetPinMux(IOMUXC_GPIO_B0_07_ARM_CM7_TRACE03, 0U);
    IOMUXC_SetPinMux(IOMUXC_GPIO_B0_12_ARM_CM7_TRACE_CLK, 0U);
 
    // enable clock
    CLOCK_EnableClock(kCLOCK_Trace);
 }


Segger J-Trace trace functionality is supported only by Ozone debugger from Segger.
It is important to properly configure trace parameters in Ozone to make it working, this could be done in menu ''Tools->Trace settings''. Recommended settings are shown on picture below.
[[File:Imxrt_trace_configuration.png|center|338px]]