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P4080 UART setting of baudrate

Question asked by sumanth mushigeri on Nov 27, 2013
Latest reply on Nov 28, 2013 by sumanth mushigeri

Hello All,


I am trying to set the buudrate of P4080 UART0, to 115200 for 333Khz DUART INPUT CLOCK.

But the Uboot upon bootup as set UDLB & UMLB  to  115,200  as   "00D9" i.e.,  for 400KHz configuration.


I can change every other DUART register value except for (UDLB & UMLB) and also send & receive data 'perfectly' using a "waiit" function ..


Please can any one tell me, where am I going wrong in it? 

If I remove this "waiit", then I won't have proper communication, I can see something like 1st character and then 6th ..randomly.




P.S : THROUGH T32 debugger have a checked the value of UDLB1 = D9 & UMLB1 = 00.

And also the communicator computer is set to 115200 as standard & is tested many a times.


Here is my code

int write(int file, char *ptr, int len) {

        unsigned int i;

        int de =1;                                  // de = 1 for write & de = 0 for read function



        /* Transmitting a char from UART */

        for (i = 0; i < len; ++i, ++ptr)


                    OUT_8(DUART1_UTHR, *ptr);

//                   waiit(); //TODO: frequency matching is not happening so, either the buffer is getting over written or the receiver is too slow.


    return len;



void waiit(){

    int i;




void initialize_Uart(int);

void initialize_Uart(int de)


#define DUART1_UTHR  0xFE11C500 //transmitter buffer register

#define DUART1_UDLB  0xFE11C500 // to set the baud rate

#define DUART1_UMLB  0xFE11C501 // higher bite of baud rate

#define DUART1_UIER1 0xFE11C501 //  Modem interrupt register  00001111

#define DUART1_UFCR1 0xFE11C502 //FIFO control register  1,0,0,0,0,1,1,1

#define DUART1_ULCR1 0xFE11C503 // Line control register, for parity and other checks

#define DUART1_UMCR1 0xFE11C504    // modem control register  0x12 for loop back & ready to send 0x00 to clear these two

#define DUART1_ULSR1 0xFE11C505 // Line status register

#define DUART1_UMSR1 0xFE11C506 // modem status register -> to check if the peripheral device is ready to transmit.

#define DUART1_UDSR1 0xFE11C510 // Check if the buffer is ready to transmit or receive


#if !defined( OUT_8 )

                #define    OUT_8(p,d)        (*(volatile char *)(p) = (char)(d))


            #if !defined( IN_8 )

                #define    IN_8(p)            ((*(volatile char *)(p)))



    if(de==1)                                                /* Initialization of UART port 1 for writing */



                OUT_8(DUART1_UIER1, 0x00);                         //disable interrupts

                //OUT_8(DUART1_ULCR1, 0x80);                         // Bank select enable

                                                                /*You can change the BAUD RATE HERE, but using default baudrate set by >U-boot is error free */

//                OUT_8(DUART1_UDLB, (baud_rate & 0xff));

//                OUT_8(DUART1_UMLB, ((baud_rate>>8)& 0xff));     //set the baud rate to 115200


                OUT_8(DUART1_UDLB, 0x0000);  // VALUE for 00B5

                OUT_8(DUART1_UMLB, 0xB500);

                OUT_8(DUART1_ULCR1, 0x03);                         // 8 bit data, 1stop, no parity

                OUT_8(DUART1_UMCR1, 0x02);                         // Ready to send/receive

                OUT_8(DUART1_UFCR1, 0x07);                         // FIFO enable | receiver soft reset | transmitter soft reset

                //OUT_8(DUART1_UIER1, 0x0f);                        // enable interrupts

                /* End of Initialization of UART port 1 */



    if(de==0)                                                    /* Initialization of UART port 1 for reading */


                OUT_8(DUART1_UIER1, 0x00);                                 //disable interrupts

                OUT_8(DUART1_UDLB, 0x0000);

                OUT_8(DUART1_UMLB, 0xB500);

                //OUT_8(DUART1_ULCR1, 0x80);                             // Bank select enable

                //OUT_8(DUART1_UDLB, (baud_rate & 0xff));

                //OUT_8(DUART1_UMLB, ((baud_rate>>8)& 0xff));             //set the baud rate to 115200

                OUT_8(DUART1_ULCR1, 0x03);                                 // 8 bit data, 1stop, no parity

                OUT_8(DUART1_UMCR1, 0x02);                                 // Ready to receive