LPC812 UART in Polling mode does not works

[ashokfair]

Hi Everyone,

Im using LPC812 MAX board,

Initially i have configured the board for two UARTs (UART0 as Debug port and UART1 as external) and it works.

later i m in need of switching the external UART into polling mode (refer to lpcOpen_3_01-> periph_uart_rom_polling)

after that Debug UART stopped working. my suspect is  "Init_UART_PinMux" something going wrong here.

i have attached the polling example , please help me asap.

any other good suggestion to communicate with esp8266 without polling ?

Thanks,

Ashok r

[jeremyzhou]

Hi Ashok Ra,

How is going on about this issue? whether you had already fixed it.
Have a great day,
TIC

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[ashokfair]

HI Zhou,

Now the things are changed , after an release of LPC812 SDK. im trying in interrupt mode. unfortunately this time changing baud-rate did not works. 

[jeremyzhou]

Hi Ashok Ra,
Thanks for your reply.
I was wondering if you can introduce the issue in details, the more information can help me to figure it out.
Have a great day,
TIC

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[ashokfair]

HI Zhou,

Thank you, sure i can explain

I am using XpressoIDE 10.2 and downloaded LPC812MAX SDK. THe default UART example baud-rate is set to 9600 for all projects (polling/interrupt/terminal). I tried to change the baud-rate in UART_Init() like below. But did not works

    USART_GetDefaultConfig(&config);
    config.baudRate_Bps = 115200;
    config.enableRx = true;
    config.enableTx = true;

    /* Initilize the USART with configuration. */
    USART_Init(EXAMPLE_USART, &config, EXAMPLE_USART_CLK_FREQ);

I believe some clock things needs to be modified , but not sure about it. please help me.

[jeremyzhou]

Hi Ashok Ra,
I'd like to suggest that you need to do some hardware circuit modification as the figure shows and give a try again.

Have a great day,
TIC

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Note: If this post answers your question, please click the Correct Answer button. Thank you!
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[ashokfair]

HI Zhou,

Thank you! But with my same LPC MAX board previously 115200 baudrate works with LPCOpen8xx Libraries.

[jeremyzhou]

Hi Ashok Ra,
Please give the modified USART_SetBaudRate()  try, it works on my site.
Have a great day,
TIC

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Note: If this post answers your question, please click the Correct Answer button. Thank you!
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status_t USART_SetBaudRate(USART_Type *base, uint32_t baudrate_Bps, uint32_t srcClock_Hz)
{
    /* check arguments */
    assert(!((NULL == base) || (0 == baudrate_Bps) || (0 == srcClock_Hz)));

#if defined(FSL_FEATURE_USART_HAS_OSR_REGISTER) && (FSL_FEATURE_USART_HAS_OSR_REGISTER)
    uint32_t best_diff = (uint32_t)-1, best_osrval = 0xf, best_brgval = (uint32_t)-1;
    uint32_t diff = 0U, brgval = 0U, osrval = 0U, baudrate = 0U;

    /* If synchronous is enable, only BRG register is useful. */
    if (base->CFG & USART_CFG_SYNCEN_MASK)
    {
        brgval = srcClock_Hz / baudrate_Bps;
        base->BRG = brgval - 1;
    }
    else
    {
        for (osrval = best_osrval; osrval >= 8; osrval--)
        {
            brgval = (srcClock_Hz / ((osrval + 1) * baudrate_Bps)) - 1;
            if (brgval > 0xFFFF)
            {
                continue;
            }
            baudrate = srcClock_Hz / ((osrval + 1) * (brgval + 1));
            diff = baudrate_Bps < baudrate ? baudrate - baudrate_Bps : baudrate_Bps - baudrate;
            if (diff < best_diff)
            {
                best_diff = diff;
                best_osrval = osrval;
                best_brgval = brgval;
            }
        }

        /* value over range */
        if (best_brgval > 0xFFFF)
        {
            return kStatus_USART_BaudrateNotSupport;
        }

        base->OSR = best_osrval;
        base->BRG = best_brgval;
    }
#else
    uint32_t brgval = 0U;
    /* If synchronous is enable. */
    if (base->CFG & USART_CFG_SYNCEN_MASK)
    {
        brgval = srcClock_Hz / baudrate_Bps;
        base->BRG = brgval - 1;
    }
    else
    {
        /* In asynchronous mode, The baud rate divider divides the common USART
         * peripheral clock by a factor of 16 multiplied by the baud rate value
         * to provide the baud rate.
         */
         brgval = srcClock_Hz / (baudrate_Bps * 16);
         if (brgval == 0) {
              brgval = 1;
         }
         SYSCON->UARTCLKDIV = brgval;

         uint32_t uart_fra_multiplier;
         RESET_PeripheralReset(kUARTFRG_RST_N_SHIFT_RSTn);
         SYSCON->UARTFRGDIV = 0xFF;
         uart_fra_multiplier = ((srcClock_Hz / brgval) * 256)/(baudrate_Bps * 16);
         SYSCON->UARTFRGMULT=uart_fra_multiplier;

        //base->BRG = brgval - 1;
    }
#endif /* FSL_FEATURE_USART_HAS_OSR_REGISTER */

    return kStatus_Success;
}‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍

[ashokfair]

Thanks TIC & Zhou

[vojtechhavlicek]

Hi,

When you initliazed these 2 uarts - this was via ROM API - interrupt mode / polling mode?

You generally dont need polling mode to communicate with device. 

[ashokfair]

I tried with below fn call..

 Chip_UART_ReadBlocking(UART1,data,length);

but not reading all bytes.

only works with length as 1,