EFM23TG840F32 UART initialise

[Octavian T. (tunea)]

Hello everybody.

I have a microcontroller EFM32TG840F32 and a UART-USB adapter.
I want to connect the UART-USB to a Pc and receive a byte from the 
terminal program from PC (like 5A="Z"in ASCII). When this byte it is 
read from the UART1 by the microcontroller, he should send back a 
character sequence - "Energy Micro". Pd0=Tx and PD1=Rx.

I have used IAR as IDE and I used the example USART from their website. 
But it looks like the initialisation of the UART it is not done and I 
receive no data. I tried also to send back what I receive in the 
receivebuffer and still does not work.

can you give me a hint to what I have done wrong?
does anyone programmed the USART1 or USART2 from this microcontroller? I 
never used it before. I attached also the code and I copy paste also my 
main functions.

///main.c

#include <string.h>
#include "efm32.h"
#include "efm32_chip.h"
#include "efm32_cmu.h"
#include "uart.h"
#include "usart.h"


/* Buffers */
char transmitBuffer[] = "Energy Micro";
#define Zet 0x5A
#define            BUFFERSIZE    (sizeof(transmitBuffer) / sizeof(char))
char receiveBuffer[];

/*********************************************************************** 
*******
 * @brief enables high frequency crystal oscillator (HFXO),
 * Sets HFCLK domain to use HFXO as source
 ************************************************************************ 
*****/
void switchToHFXO(void)
{
  CMU_TypeDef *cmu = CMU;

  /* Turning on HFXO to increase frequency accuracy. */
  /* Waiting until oscillator is stable */
  cmu->OSCENCMD = CMU_OSCENCMD_HFXOEN;

  while (!(cmu->STATUS && CMU_STATUS_HFXORDY)) ;

  /* Switching the CPU clock source to HFXO */
  cmu->CMD = CMU_CMD_HFCLKSEL_HFXO;

  /* Turning off the high frequency RC Oscillator (HFRCO) */
  /* GENERATL WARNING! Make sure not to disable the current
   * source of the HFCLK. */
  cmu->OSCENCMD = CMU_OSCENCMD_HFRCODIS;
}



/*********************************************************************** 
*******
 * @brief initializing uart settings
 *
 ************************************************************************ 
*****/
void init(void)
{
  /* Using HFXO to have max frequency accuracy */
  switchToHFXO();

 // CMU_ClockEnable(cmuClock_GPIO, true);


   /* Setup UART */
  UART_setupUart(USART1_NUM, GPIO_POS1);

    /* Enabling clock to USART 1 and 2*/
  CMU_ClockEnable(cmuClock_USART1, true);
}


/*********************************************************************** 
*******
 * @brief  Main function
 * Main is called from _program_start, see assembly startup file
 ************************************************************************ 
*****/
int main(void)
{
  /* Initialize chip */
  CHIP_Init();

  /* Initalizing */
  init();

/* Clearing the receive buffer */
memset(receiveBuffer, '\0', 1);

  while(receiveBuffer[0]!=Zet)

  {
    /* Transmitting data */
  /* Transmission is polled */
    UART1_receiveBuffer(receiveBuffer,1);
    USART1_sendBuffer(receiveBuffer, 1);
  }
      USART1_sendBuffer(transmitBuffer, BUFFERSIZE);

  /* Done! */
  while (1) ;
}


/*this is my UART.C file*/

#include "efm32.h"
#include "uart.h"
#include "efm32_gpio.h"
#include "uart_project.h"
#include "usart.h"
#include "efm32_cmu.h"

#include <string.h>

/* Buffer pointers and indexes */
char* txBuffer;
char* rxBuffer;
int txBufferSize;
int rxBufferSize;
volatile int txBufferIndex;
volatile int rxBufferIndex;



/*********************************************************************** 
***//**
 * @brief Setup a USART to be used in asynchronous (UART) mode
 * @param usartNumber is the number of the USART to use (e.g. 1 for 
USART1)
 * @param location is the IO location to use
 ************************************************************************ 
*****/
void UART_setupUart(uint8_t uartNumber, uint8_t location)
{
  USART_TypeDef* uart = USART1;


  /* Configure USART as uart - 8-N-1 */
  uart->FRAME &= ~(
    _USART_FRAME_DATABITS_MASK |
    _USART_FRAME_PARITY_MASK |
    _USART_FRAME_STOPBITS_MASK);
  uart->FRAME |= (
    USART_FRAME_DATABITS_EIGHT |
    USART_FRAME_PARITY_NONE |
    USART_FRAME_STOPBITS_ONE
    );


  /* Setting baudrate */
  uart->CLKDIV = 256 * ((UART_PERCLK_FREQUENCY / (16 * UART_BAUDRATE)) - 
1);


  /* Enable RX/TX */
  uart->CMD = USART_CMD_RXEN | USART_CMD_TXEN;

   /* Enable RX and TX pins and set location */
  uart->ROUTE = USART_ROUTE_RXPEN | USART_ROUTE_TXPEN | (1 << 8);

  /* Clear RX/TX buffers */
  uart->CMD = USART_CMD_CLEARRX | USART_CMD_CLEARTX;


  /* Use default location 0: TX - Pin D0, RX - Pin D1 */
  /* To avoid false start, configure output as high */
 GPIO_PinModeSet(gpioPortD, 0, gpioModePushPull, 0);

  /* Define input, no filtering */
 GPIO_PinModeSet(gpioPortD, 1, gpioModeInput, 0);

 GPIO_PinModeSet(gpioPortD, 1, gpioModeInputPull, 0);


}


/*********************************************************************** 
***//**
 * @brief Receiving data from USART1
 * @param receiveBuffer is pointing to where data is to be stored.
 * @param bytesToReceive is the number of bytes to receive
 ************************************************************************ 
*****/
void UART1_receiveBuffer(char* receiveBuffer, int bytesToReceive)
{
  USART_TypeDef *uart = USART1;
  int           ii;

  /* Receiving data */
  for (ii = 0; ii < bytesToReceive;  ii++)
  {
    /* Waiting for the usart to be ready */
 while (!(uart->STATUS & USART_STATUS_RXDATAV)) ;

    /* Writing next byte to USART */
    *receiveBuffer = uart->RXDATA;
    receiveBuffer++;
  }
}

/*********************************************************************** 
*******
 * @brief sends data using USART1
 * @param txBuffer points to data to transmit
 * @param bytesToSend bytes will be sent
 ************************************************************************ 
*****/
void USART1_sendBuffer(char* txBuffer, int bytesToSend)
{
  USART_TypeDef *uart = USART1;
  int           ii;

  /* Sending the data */
  for (ii = 0; ii < bytesToSend;  ii++)
  {
    /* Waiting for the usart to be ready */
  while (!(uart->STATUS & USART_STATUS_TXBL)) ;

    if (txBuffer != 0)
    {
      /* Writing next byte to USART */
      uart->TXDATA = *txBuffer;
      txBuffer++;
    }
    else
    {
      uart->TXDATA = 0;
    }
  }

  /*Waiting for transmission of last byte */
  while (!(uart->STATUS & USART_STATUS_TXC)) ;
}


thank you.

[Ben j. (scarab)]

i dont looked through the whole code but common errors on 
EnergyMicro-Controllers are:

- you dont enabled the peripheral clock (-> all peripherals are 
disabled, you cant even set a GPIO )
- your GPIO-PinModes doesn't match the ROUTE of your UART
- your using the wrong registers to read out the buffer (there i 
register that returns the byte for the UART but doesnt delete this byte 
from the buffer)

maybe u should try to use energyAware Designer to generate the 
Initialisation.

Also the EM support is very fast:
http://support.energymicro.com/anonymous_requests/new

[Octavian T. (tunea)]

Hello.

thank you for the answear. I enabled all clocks - GPIO clock and UART 
clock.
The GPIO pin initialising I took it from the Energy Aware designer which 
generates the code for something you need on this board.
When it comes to registers I am not sure about my code but I do not know 
exactly where to look.

in the datasheet it is written that for transmission I must set 
TxEN(from USARTn_CMD register), disable TxDIS (from USARTn_CMD 
register), load frame - write to  USARtn_TxDATA

for the receive I use RxDATAV to validate data.

I already wrote them also but they say I did something wrong with the 
interrupts, but I use no interrupts or maybe something in the UART 
initialising is not ok.
Thanks

[Jim M. (turboj)]

You need to enable clocks before accessing perpherials in your init() 
function:

  /* Enabling clock to USART 1*/
  CMU_ClockEnable(cmuClock_USART1, true);

  /* Setup UART */
  UART_setupUart(USART1_NUM, GPIO_POS1);

[Octavian T. (tunea)]

I have solved the promblem. the board Tiny gecko had a problem with this 
UART. I tried it on another board - Starter Kit EFM32G890F128 and it 
worked.

I attach the final code. this code sends back the bytes it receives from 
the PC. I tested it with Terminal by br@y.

Have a nice day everybody.