Finally, I found out that the firmware is loading and starting correctly with the procedure I outlined above.
My first mistake was a wrong MCUXpressoIDE project configuration to compile. Althoug I was getting a binary, this code wasn’t starting.
Later I tried with the .bat scripts included in example projects and I was able to view the blink led in the pin mapped for gpio example.
In other topics (Colibri iMX8X Cortex M4 FreeRTOS - #8 by benjamin.tx) I suspect that were given incomplete information, since debug UART is not configured throug “pin_mux” files.
Instead, debug uart for log messages are configured by BOARD_InitDebugConsole(void) in “board.c”.
I point to the changes I made to get UART output in B port for Iris Carrier Board here
/* Initialize debug console. */
uint32_t freq = SC_133MHZ;
/* Power on Local LPUART for M4 Core0. */
sc_pm_set_resource_power_mode(ipcHandle, SC_R_UART_0, SC_PM_PW_MODE_ON);
/* Enable clock of Local LPUART for M4 Core0. */
/* Set clock Frequncy of Local LPUART for M4 Core0. */
freq = CLOCK_SetIpFreq(kCLOCK_DMA_Lpuart0, freq);
/* Initialize Debug Console using local LPUART for M4 Core0. */
DbgConsole_Init(BOARD_DEBUG_UART_INSTANCE, BOARD_DEBUG_UART_BAUDRATE, BOARD_DEBUG_UART_TYPE, freq);
/* The UART to use for debug messages. */
#define BOARD_DEBUG_UART_TYPE kSerialPort_Uart
#define BOARD_DEBUG_UART_BAUDRATE 115200u
#define BOARD_DEBUG_UART_BASEADDR (uint32_t) ADMA__LPUART0
#define BOARD_DEBUG_UART_INSTANCE 0U
#define BOARD_DEBUG_UART_SC_RSRC SC_R_UART_0
#define BOARD_DEBUG_UART_CLK_FREQ 6000000u
#define BOARD_UART_IRQ M4_LPUART_IRQn
#define BOARD_UART_IRQ_HANDLER ADMA_UART0_INT_IRQn
#define BOARD_DEBUG_UART_CLKSRC kCLOCK_DMA_Lpuart0
#define BOARD_M4_CPU_RSRC SC_R_M4_0_PID0 //?
#define BOARD_BASEBOARD_PWR_GPIO LSIO_GPIO5
#define BOARD_BASEBOARD_PWR_GPIO_PIN 9U
I hope this would help another users.
I am a little sad about not receiveing response at this point…
I also add how to load with a TFTP server called Tftpd64 in windows 10
U-boot dhcp command seems to have a weird behavior (tries to load a default image), but setting connection ip manually loading works fine