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RS485

Hello, I am working in mdk5. For my application I am writting code for RS485. While debugging I found that my FCR register is not loading its value. The code I have written is show below.
void uart_rs485(void)
{ SCU_PinConfigure(2,3, SCU_CFG_MODE_FUNC2);// p2_3 for U3_TXD SCU_PinConfigure(2,4, SCU_CFG_MODE_FUNC2);// p2_4 for U3_RXD GPIO_SetDir(4,11,GPIO_DIR_OUTPUT);// Set GIO_B1_RS485_DIR as output

LPC_USART3->LCR = 0x83;// Line Control Register LPC_USART3->FCR =0x07;//FIFO buffer LPC_USART3->FDR =0;// Fractional Divide LPC_USART3->DLM =0;//Divide Latch MSB LPC_USART3->DLL =98;//Divide Latch LSB LPC_USART3->LCR =0x03;//Disable DLAB

}
void uart_rs485_transmit(void)
{ GPIO_PinWrite(4,11,1);//Making Transmit Enable high if(LPC_USART3->LSR & 0x20) { LPC_USART3->THR = 83; }
}

void uart_rs485_receive(void)
{ GPIO_PinWrite(4,11,0);//Receive Enable a = LPC_USART3->RBR;
} Please help me in this flow. Thank you in advance

Parents

0 Rajesh Pillai over 8 years ago in reply to Rajesh Pillai

Hi all, While dealing with UART1 of LPC1857 to be used as RS232 I have coded as below.
For providing clock:

void SCI_PortClock (uint32_t clock) {
  if (clock) {
    LPC_CCU1->CLK_M3_UART1_CFG |= 3;
    while (!(LPC_CCU1->CLK_M3_UART1_STAT & 1));
  }
  else {
    LPC_CCU1->CLK_M3_UART1_CFG   &= ~(3);
    while (LPC_CCU1->CLK_M3_UART1_STAT & 1);
  }
}

Pin configuration and UART configuration:

RS232 PINS
U1_TXD = P3_4
U1_RXD = P3_5
*/
const PIN_ID RS232_PIN[] = {
  { RTE_UART1_RX_PORT, RTE_UART1_RX_BIT, (RTE_UART1_RX_FUNC | SCU_SFS_EZI)},
  { RTE_UART1_TX_PORT, RTE_UART1_TX_BIT, (RTE_UART1_TX_FUNC)}
};


void uart_sci(void)
{
        const PIN_ID *pin;
        SCI_PortClock (1);
        for (pin = RS232_PIN; pin != &RS232_PIN[sizeof(RS232_PIN)/sizeof(PIN_ID)]; pin++) {
    if (pin->port == 0x10) {
      SCU_CLK_PinConfigure (pin->num, pin->config_val);
      continue;
    }
    SCU_PinConfigure(pin->port, pin->num, pin->config_val);
  }

        LPC_UART1->LCR = 0x83;     //Line Control Register
        LPC_UART1->FDR = 0;        //Fractional Divide
        LPC_UART1->DLM = 0;        //Divide Latch MSB
        LPC_UART1->DLL = 98;       //Divide Latch LSB
        LPC_UART1->LCR = 0x03;     //Disable DLAB
        LPC_UART1->FCR = 0x07;     //FIFO buffer
}
void uart_sci_transmit(void)
{

        if(LPC_UART1->LSR & 0x20)
        {
                LPC_UART1->THR = 83;
        }
}

void uart_sci_receive(void)
{

        a = LPC_UART1->RBR;
}

While debugging, I came to know that FCR, DLL, DLM are not configured as I have given.
Transmission and reception is unsuccessful. LCR is loaded properly. Inviting your valuable suggestions. I am using Keil MDK5.

Reply

0 Rajesh Pillai over 8 years ago in reply to Rajesh Pillai

Hi all, While dealing with UART1 of LPC1857 to be used as RS232 I have coded as below.
For providing clock:

void SCI_PortClock (uint32_t clock) {
  if (clock) {
    LPC_CCU1->CLK_M3_UART1_CFG |= 3;
    while (!(LPC_CCU1->CLK_M3_UART1_STAT & 1));
  }
  else {
    LPC_CCU1->CLK_M3_UART1_CFG   &= ~(3);
    while (LPC_CCU1->CLK_M3_UART1_STAT & 1);
  }
}

Pin configuration and UART configuration:

RS232 PINS
U1_TXD = P3_4
U1_RXD = P3_5
*/
const PIN_ID RS232_PIN[] = {
  { RTE_UART1_RX_PORT, RTE_UART1_RX_BIT, (RTE_UART1_RX_FUNC | SCU_SFS_EZI)},
  { RTE_UART1_TX_PORT, RTE_UART1_TX_BIT, (RTE_UART1_TX_FUNC)}
};


void uart_sci(void)
{
        const PIN_ID *pin;
        SCI_PortClock (1);
        for (pin = RS232_PIN; pin != &RS232_PIN[sizeof(RS232_PIN)/sizeof(PIN_ID)]; pin++) {
    if (pin->port == 0x10) {
      SCU_CLK_PinConfigure (pin->num, pin->config_val);
      continue;
    }
    SCU_PinConfigure(pin->port, pin->num, pin->config_val);
  }

        LPC_UART1->LCR = 0x83;     //Line Control Register
        LPC_UART1->FDR = 0;        //Fractional Divide
        LPC_UART1->DLM = 0;        //Divide Latch MSB
        LPC_UART1->DLL = 98;       //Divide Latch LSB
        LPC_UART1->LCR = 0x03;     //Disable DLAB
        LPC_UART1->FCR = 0x07;     //FIFO buffer
}
void uart_sci_transmit(void)
{

        if(LPC_UART1->LSR & 0x20)
        {
                LPC_UART1->THR = 83;
        }
}

void uart_sci_receive(void)
{

        a = LPC_UART1->RBR;
}

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