UART2 clock configuration in TWR-K53N512

[communitycommun]

How to setup the clock configuration for uart 2 in TWR K53N512 in IAR,i we have selected the default core clock as 50 Mhz later its calculated in peripheral clock and then that its pushed into uart_init for further processing..

But at the Real term and the tera term are showing the junk value....

#define REF_CLK	XTAL8	//XTAL8
#define CORE_CLK_MHZ	PLL50	/* system/core frequency in MHz */

main()

{

          core_clk_mhz = pll_init(CORE_CLK_MHZ, REF_CLK);

                  core_clk_khz = core_clk_mhz * 1000;

         periph_clk_khz = core_clk_khz / (((SIM_CLKDIV1 & SIM_CLKDIV1_OUTDIV2_MASK) >> 24)+ 1);

       /* Enable the UART2_TXD function on PTD3 */

          PORTD_PCR3 = PORT_PCR_MUX(0x3); // UART is alt3 function for this pin

          /* Enable the UART2_RXD function on PTD2 */

         PORTD_PCR2 = PORT_PCR_MUX(0x3); // UART is alt3 function for this pin 

       uart_init (UART2_BASE_PTR, periph_clk_khz, 115200 );

while(1)

{

uart_putchar(UART2_BASE_PTR ,'a');

}

}

void uart_init (UART_MemMapPtr uartch, int sysclk, int baud)

{

    register uint16 sbr, brfa;

    uint8 temp;

    /* Enable the clock to the selected UART */   

    if(uartch == UART0_BASE_PTR)

        SIM_SCGC4 |= SIM_SCGC4_UART0_MASK;

    else

        if (uartch == UART1_BASE_PTR)

            SIM_SCGC4 |= SIM_SCGC4_UART1_MASK;

        else

            if (uartch == UART2_BASE_PTR)

                SIM_SCGC4 |= SIM_SCGC4_UART2_MASK;

            else

                if(uartch == UART3_BASE_PTR)

                    SIM_SCGC4 |= SIM_SCGC4_UART3_MASK;

                else

                    if(uartch == UART4_BASE_PTR)

                        SIM_SCGC1 |= SIM_SCGC1_UART4_MASK;

                    else

                        SIM_SCGC1 |= SIM_SCGC1_UART5_MASK;

    /* Make sure that the transmitter and receiver are disabled while we

     * change settings.

     */

    UART_C2_REG(uartch) &= ~(UART_C2_TE_MASK

                | UART_C2_RE_MASK );

    /* Configure the UART for 8-bit mode, no parity */

    UART_C1_REG(uartch) = 0;    /* We need all default settings, so entire register is cleared */

    /* Calculate baud settings */

    sbr = (uint16)((sysclk*1000)/(baud * 16));

    /* Save off the current value of the UARTx_BDH except for the SBR field */

    temp = UART_BDH_REG(uartch) & ~(UART_BDH_SBR(0x1F));

    UART_BDH_REG(uartch) = temp |  UART_BDH_SBR(((sbr & 0x1F00) >> 8));

    UART_BDL_REG(uartch) = (uint8)(sbr & UART_BDL_SBR_MASK);

    /* Determine if a fractional divider is needed to get closer to the baud rate */

    brfa = (((sysclk*32000)/(baud * 16)) - (sbr * 32));

    /* Save off the current value of the UARTx_C4 register except for the BRFA field */

    temp = UART_C4_REG(uartch) & ~(UART_C4_BRFA(0x1F));

    UART_C4_REG(uartch) = temp |  UART_C4_BRFA(brfa);   

    /* Enable receiver and transmitter */

    UART_C2_REG(uartch) |= (UART_C2_TE_MASK

                | UART_C2_RE_MASK );

        /* Enable interrupt on reception*/

         // UART_C2_REG(UART_C2_RIE_MASK) |= UART_C2_RIE_MASK;

         /* UART3_C2 |= UART_C2_RIE_MASK;  */ // old code was previously enabled

}

[Robin_Shen]

Hi,

Please try to use below pads.

Best Regards,

Robin

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[Alice_Yang]

Hello Binbin,

When you use the UART3, do you connect the UART port of TWR-SER board , the J8 port.

This is link to UART3, while the  UART2 not connected to J8 of TWR-SER .

So if you want to use the UART2, you need connect the pins by yourself .

BR

Alice

[Alice_Yang]

Hello ,

Only from the code you show is no error.

Which clock mode does your chip run ? How do you know the core clock is 50M?

There is TWR-K53 demo , including UART, you can run this on your board to check.

K53 example code

And it run on CW, you can create one IAR project ,then copy the application to the project .

Pay attention that , it use the UART5, the clock method configuration is the same.

Hope it helps

Have a great day,
Alice

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[communitycommun]

Thanks for the reply....
i have copied by code from that file only ,the think is when uart3 is given with peripheral clock its working ,but the same peripheral clock applied to uart2 is not ...
in my project already uart3 is in use so i can't use it that's why i am trying with uart2...
in uart2 case the data are transmitting but it's a type of junk,its definitely due mismatch of clock WRT core and peripheral...
still under confusion how to check and work with this

Thanks for the help

[Alice_Yang]

Hello ,

If the UART3 can work well use the same bus clock source , while the UART2 can

not work ,  i recommend you check the hardware , on TWR-K53, how do you use the  UART2？

BR

Alice