Making UART work on CC2541

andrey goverdovskiy

So i'm trying to add UART functionality to my project on SensorTag board.

Here's how the initialisation happens:

First, main() function calls HalDriverInit(), which calls HalUARTInit(), which calls HalUARTInitDMA(), since i've configured UART to work in DMA mode using HAL_UART_DMA = 2 symbol.

Then i initialise UART parameters in MyApplication_Init() function the following way:

  {
    halUARTCfg_t uartConfig;

    uartConfig.configured           = TRUE;
    uartConfig.baudRate             = HAL_UART_BR_9600;
    uartConfig.flowControl          = FALSE;
    uartConfig.flowControlThreshold = 0;
    uartConfig.rx.maxBufSize        = 128;
    uartConfig.tx.maxBufSize        = 128;
    uartConfig.idleTimeout          = 10;
    uartConfig.intEnable            = TRUE;
    uartConfig.callBackFunc         = (halUARTCBack_t)UART_CB;

    // start UART
    // Note: Assumes no issue opening UART port.
    if ( HalUARTOpen( HAL_UART_PORT_1, &uartConfig ) != HAL_UART_SUCCESS )
      HalLedBlink( HAL_LED_2, 15, 50, 50 );
    else
    {
      uint8 *msg = "UART configured";
      uint8 msgLen = strlen(msg);
      if (HalUARTWrite(HAL_UART_PORT_1, msg, msgLen) != msgLen)
        HalLedBlink( HAL_LED_2, 15, 50, 50 );
    }
  }

No blinking happens, so i know the configuration is successful and the message has been sent. However, i can see no signal on the Tx pin (P1.5). Why?

over 10 years ago

0 Arun Menon over 10 years ago

TI__Expert 6505 points

Hi,

SensorTag exposes only USART0 only with Alt-2 lines. Defining HAL_UART_DMA alone will not do the trick. So you need changes in your pin mapping configuration to reflect the correct pins and configure your registers accordingly.

Please apply the following settings

/* Test USART 0 on P1.4 and P1.5 */

PERCFG |= 0x01; // Set UART0 to Alternative 2 location

P1SEL |= 0x30;

U0CSR |= 0x80; // USART mode = UART (UxCSR.MODE = 1)

U0UCR |= 0x01; // Start bit level = high => Idle level = low (U1UCR.START = 1)

U0UCR &= ~0x02; // Stop bit level = low (U1UCR.STOP = 0)

U0UCR &= ~0x04; // Number of stop bits = 1 (U1UCR.SPB = 0)

U0UCR |= 0x08; // Parity = enabled (U1UCR.PARITY = 1)

U0UCR &= ~0x10; // 9-bit data disable = 8 bits transfer (U1UCR.BIT9 = 0)

U0UCR |= 0x20; // Parity = Even (U1UCR.D9 = 0)

U0UCR &= ~0x40; // Flow control = disabled (U1UCR.FLOW = 0)

U0GCR &= ~0x20; // Bit order = LSB first (U1GCR.ORDER = 0) => For PC/Hyperterminal

U0BAUD = 59; // BAUD_M = 59 and BAUD_E = 8 => Baud rate of 9600

U0GCR &= ~0x1F; // Clear BAUD_E bits

U0GCR |= 0x08; // BAUD_E = 8

Also disable UART flow control UART_FC = FALSE( in NPI.h)

Regards,

Arun

0 Arun Menon over 10 years ago in reply to Arun Menon

TI__Expert 6505 points

Please make the changes as given below

While building the project, we had the following symbols enabled in our pre processor.

HAL_DMA=TRUE

HAL_LCD=FALSE

HAL_UART=TRUE

HAL_UART_DMA=1

HAL_KEY=FALSE

NPI_UART_PORT=HAL_UART_PORT_0

We had turned of the flow control in NPI.h - #define NPI_UART_FC FALSE

Also in _hal_uart_dma.c we did the following register changes.

#if (HAL_UART_DMA == 1)

#define PxSEL P1SEL
#define HAL_UART_PERCFG_BIT 0x01 // USART0 on P1, Alt-2;
#define HAL_UART_PRIPO 0x00 // USART0 priority over UART1.
#define HAL_UART_Px_CTS 0x04 // Peripheral I/O Select for CTS flow control.
#define HAL_UART_Px_RTS 0x08 // Peripheral I/O Select for RTS must be manual.
#define HAL_UART_Px_SEL 0x30 // Peripheral I/O Select for Rx/Tx.

#if (HAL_UART_DMA == 1)
#define PxDIR P1DIR
#define PxIEN P1IEN
#define PxIFG P1IFG
#define PxIF P1IF
#define DMA_RDYIn P1_2
#define DMA_RDYOut P1_3

Also in HalUARTInitDMA() set PERCFG |= HAL_UART_PERCFG_BIT

Regards,

Arun

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Making UART work on CC2541