Changing Baud Rate & Parity in Run time

[miltongdavid]

I want to change the Baud rate and parity of an UART on reception of some commands. Does MQX has any API to do it

[DavidS]

Hope this helps.  I haven't tried the parity yet but assume it is very similar.

fh_ptr = (pointer)fopen("ittyb:", BSP_DEFAULT_IO_OPEN_MODE); //Interrupt mode uart1
BSP_DEFAULT_IO_OPEN_MODE); //Interrupt mode uart2
   if (fh_ptr == NULL) {
      printf("cannot open file: ittyb\n");  //print to uart1
   } else {
      printf("\nittyb: Device Handler opened successfully\n");  //print to uart1
      fflush(stdout);
   }
   
   write(fh_ptr,(pointer)"\n",1); // write 1 char to uart1 or uart2
   write(fh_ptr,(pointer)"Q",1); // write 1 char to uart1 or uart2
   write(fh_ptr,(pointer)"\n",1); // write 1 char to uart1 or uart2
   write(fh_ptr,(pointer)"QQ",2); // write 2 char to uart1 or uart2
   write(fh_ptr,(pointer)"\n",1); // write 1 char to uart1 or uart2
   write(fh_ptr,(pointer)"QQQ",3); // write 3 char to uart1 or uart2
   write(fh_ptr,(pointer)"\n",1); // write 1 char to uart1 or uart2
   
   err = _io_ioctl(fh_ptr, IO_IOCTL_SERIAL_GET_BAUD, &Old_Baud_rate);      //Get Baud Rate from default to "Baud_rate"
   printf("\nCurrent Baud Rate for alternate UART port is %d\n", Old_Baud_rate); //print to uart0
   err = _io_ioctl(fh_ptr, IO_IOCTL_SERIAL_SET_BAUD, &New_Baud_rate);      //Change/set Baud Rate from default to "Baud_rate"
   printf("\nNew Baud Rate for alternate UART port is %d\n", New_Baud_rate);  //print to uart0
  
Regards,

David

[miltongdavid]

Thanks for the Reply. Baud works but trying to change Parity returns "IO_ERROR_INVALID_IOCTL_CMD" error.

[DavidS · Accepted solution]

The parity IOCTL command isn't fully implemented in FSLMQX3.5.

If you want to add it, try the following steps for polled UART mode.

1) to the mcf522xx_uart.h add the line with comment //DES below:

/*------------------------------------------------------------------------*/
/*
** UART registers
*/
#define MCF52XX_UART_UMR1_RXRTS             (0x80)
#define MCF52XX_UART_UMR1_RXIRQ             (0x40)
#define MCF52XX_UART_UMR1_ERR               (0x20)
#define MCF52XX_UART_UMR1_EVEN_PARITY       (0x00)
#define MCF52XX_UART_UMR1_ODD_PARITY        (0x04)
#define MCF52XX_UART_UMR1_LOW_PARITY        (0x08)
#define MCF52XX_UART_UMR1_HI_PARITY         (0x0C)
#define MCF52XX_UART_UMR1_NO_PARITY         (0x10)
#define MCF52XX_UART_UMR1_MASK_PARITY_BITS (0x1C)  //DES

2) in serl_pol_mcf522xx.c add the following case statements to function _mcf52xx_uart_serial_polled_ioctl():

case IO_IOCTL_SERIAL_SET_PARITY:  //DES
   tmp = io_info_ptr->INIT.UMR1_VALUE & ~(0x1C); //DES should make 0x1c=MCF52XX_UART_UMR1_MASK_PARITY_BITS
         tmp |=                             (*param_ptr == 0x00)
            ? MCF52XX_UART_UMR1_EVEN_PARITY : (*param_ptr == 0x04)
            ? MCF52XX_UART_UMR1_ODD_PARITY :  (*param_ptr == 0x08)
            ? MCF52XX_UART_UMR1_LOW_PARITY :  (*param_ptr == 0x0C)
            ? MCF52XX_UART_UMR1_HI_PARITY :   (*param_ptr == 0x10)
            ? MCF52XX_UART_UMR1_NO_PARITY :  MCF52XX_UART_UMR1_NO_PARITY;
         uart_ptr->WRITE.UCR = MCF52XX_UART_UCR_RESET_POINTER;
         io_info_ptr->INIT.UMR1_VALUE = tmp;
         uart_ptr->WRITE.UMR = io_info_ptr->INIT.UMR1_VALUE;
         break;
      case IO_IOCTL_SERIAL_GET_PARITY:  //DES
         *param_ptr = io_info_ptr->INIT.UMR1_VALUE & 0x1C;
         break;

3) re-compile the build_libs.mcp

4) to your application code you can try the following IOCTL commands:

   err = _io_ioctl(fh_ptr, IO_IOCTL_SERIAL_GET_PARITY, &Old_Parity);      //Get Parity from default to "Baud_rate"
   printf("\nCurrent Parity for alternate UART port is %d\n", Old_Parity);  //print to uart0
   err = _io_ioctl(fh_ptr, IO_IOCTL_SERIAL_SET_PARITY, &New_Parity);      //Change/set Parity from default to "New_Parity"
   printf("\nNew Parity for alternate UART port is %d\n", New_Parity);   //print to uart0

I've attached the source files as well.  The example app came from mqx/examples/io.

NOTE: I've only done limited testing.  You should do additional testing to ensure it does what you want.  I'm also assuming very similar code for the Interrupt UART mode.

Regards,

David

[miltongdavid]

Iam using MCF51CN128. I tried changing in the file under the respective folder. But the port hangs.

[DavidS]

Hope this helps.

fh_ptr = (pointer)fopen("ittyb:", BSP_DEFAULT_IO_OPEN_MODE); //Interrupt mode uart1
   if (fh_ptr == NULL) {
      printf("cannot open file: ittyb\n");  //print to uart1
   } else {
      printf("\nittyb: Device Handler opened successfully\n");  //print to uart1
      fflush(stdout);
   }
   
   write(fh_ptr,(pointer)"\n",1); // write 1 char to uart1 or uart2
   write(fh_ptr,(pointer)"Q",1); // write 1 char to uart1 or uart2
   write(fh_ptr,(pointer)"\n",1); // write 1 char to uart1 or uart2
   write(fh_ptr,(pointer)"QQ",2); // write 2 char to uart1 or uart2
   write(fh_ptr,(pointer)"\n",1); // write 1 char to uart1 or uart2
   write(fh_ptr,(pointer)"QQQ",3); // write 3 char to uart1 or uart2
   write(fh_ptr,(pointer)"\n",1); // write 1 char to uart1 or uart2
   
   err = _io_ioctl(fh_ptr, IO_IOCTL_SERIAL_GET_BAUD, &Old_Baud_rate);      //Get Baud Rate from default to "Baud_rate"
   printf("\nCurrent Baud Rate for alternate UART port is %d\n", Old_Baud_rate); //print to uart0
   err = _io_ioctl(fh_ptr, IO_IOCTL_SERIAL_SET_BAUD, &New_Baud_rate);      //Change/set Baud Rate from default to "Baud_rate"
   printf("\nNew Baud Rate for alternate UART port is %d\n", New_Baud_rate);  //print to uart0
  
I assume the parity works similarly but haven't tried it yet.