RE: PROCESSOR-SDK-AM62X: M4F Main Domain UART errors

Hello KC Wong,

I have split your UART question into a separate thread, and I am reassigning it to another team member who is more familiar with the MCU+ UART driver. Please ping the thread if you do not get a response within a couple of business days.

Regards,

Nick

OK, thanks Nick.

Also, I am looking for API to change the UART buad rate, but did not find one.

software-dl.ti.com/.../group__DRV__UART__MODULE.html

Our application is required to support different baud rate configuration. How to change the UART buad rate in M4F core application ?

rgds,

kc Wong

Sorry, I accidentally pressed the "This resolved my issue" button. I found no way to undo that.

We are indeed following the steps that your suggested for the development.




And we have our initial baud rate set using the SysConfig tool in the CCS.

But, we need the baud rate to change at run time and not fixed to this initial baud rate for all the use cases.

Also, can we change the Clock Freq to 50000000 instead of the default 48000000 ???

It is because some of the baud rates that we need has less error with 50MHz clock frequency.

Hi Kiung,

I would suggest to not change the UART baud rate on the go, as this might result in unambiguity down the line when your production code grows.

But if you are interested to do so, I think the best way to do would be by having a gap of lets say 30 seconds, between your last UART write or Read operation and then you can wait for 30 seconds and enter the new baud rate(as its dynamic). If you do not enter the new baud rate in 30 seconds, then the timer has expired and the operation would happen at the original baud rate. If you give the input, the new baud rate will be applied.

This is what I would have preferred to do if I had a use case of Dynamic UART Baud Rate.

Well, currently there is no API which does so, but you can create one. 

I am currently browsing through TRM and will help you by seeing which register is responsible for baud rate.

Please allow me sometime on this.

Regards,

Vaibhav

Hi Vaibhav,

Thanks for the info. I am actually aware of those registers and that formula from spruiv7b reference manual.

I am currently using the UART_close() and UART_open() APIs whenever there is a need to change the baud rate.

AM62x MCU+ SDK: APIs for UART (ti.com)

bool Uart::SetBaudRate(uint32_t baudrate)
{
    switch (baudrate)
    {
        case 300:     
        case 9600:
        case 115000:  
        case 115200:
        case 390625:  
        case 460000:  
        case 781250:  
        case 3000000:
        case 3125000: 
        break;
        default:
            DebugP_logError("Unsupported baud rate %d !!!\r\n", baudrate);
            return false;
    }

    {
        UART_close(gUartHandle[UART1]);

        UART_Params *prms = &gUartParams[UART1];
        prms->baudRate = baudrate;
        prms->operMode = UART_OPER_MODE_16X;

        // Based on SysConfig tool ...
        if (baudrate == 390625 ||
            baudrate == 460000 ||
            baudrate == 781250 ||
            baudrate == 3125000)
        {
            prms->operMode = UART_OPER_MODE_13X;
        }

        gUartHandle[CROSSGUARD_UART] = UART_open(UART1, prms);
        if(NULL == gUartHandle[UART1])
        {
            DebugP_logError("Failed to set baud rate !!!\r\n");
            return false;
        }
    }

    return true;
}

Is the implementation of UART_close() and UART_open() APIs available on the public git repository?

It will be very helpful if TI can share the implementation, especially the UART_open() API. Would like to see the implementation that actually sets the baud rate behind this API.

And I did try to change the Clock Freq to 50000000 in SysConfig tool in the CCS and the M4F application just hang.

Also, the code generated from SysConfig tool in "ti_power_clock_config.c" always uses the "TISCI_DEV_UART1_FCLK_CLK" as the clock source for UART1.

SOC_ModuleClockFrequency gSocModulesClockFrequency[] = {
    { TISCI_DEV_UART1, TISCI_DEV_UART1_FCLK_CLK, 48000000 },
    { TISCI_DEV_MCU_UART0, TISCI_DEV_MCU_UART0_FCLK_CLK, 48000000 },

    { SOC_MODULES_END, SOC_MODULES_END, SOC_MODULES_END },
};

Is it possible to use other clock source as listed below in "tisci_clocks.h".

#define TISCI_DEV_UART1_FCLK_CLK 0
#define TISCI_DEV_UART1_FCLK_CLK_PARENT_USART_PROGRAMMABLE_CLOCK_DIVIDER_OUT1 1
#define TISCI_DEV_UART1_FCLK_CLK_PARENT_HSDIV4_16FFT_MAIN_1_HSDIVOUT1_CLK 2
#define TISCI_DEV_UART1_VBUSP_CLK 5

My understanding that  "TISCI_DEV_UART1_FCLK_CLK"  is fixed to 48000000.

Among the other 3 clock sources, which one is actually 160MHz or 192MHz? Is this clock source frequency is fixed or configurable?

How to configure other clock source to produce 50000000? An actual working code implementation will be helpful.

rgds,

kc Wong

Greetings Kiung,

If you have already installed the MCU PLUS SDK for AM62x, then you do not need to search anywhere else for the API.

Both UART Open and Close implementation is available under source/drivers/uart/v0/uart_v0.c

I hope this reference helps.

Regards,

Vaibhav

So, is it possible to use other clock source for UART1 in M4Fcore ? If yes, how ?

#define TISCI_DEV_UART1_FCLK_CLK 0
#define TISCI_DEV_UART1_FCLK_CLK_PARENT_USART_PROGRAMMABLE_CLOCK_DIVIDER_OUT1 1
#define TISCI_DEV_UART1_FCLK_CLK_PARENT_HSDIV4_16FFT_MAIN_1_HSDIVOUT1_CLK 2
#define TISCI_DEV_UART1_VBUSP_CLK 5

Hi Vaibhav,

Thanks for the infor.

So, what is the value that we can set for the UART1 clock frequency?

Is it just limited to 48 MHz, 92 MHz, 196 MHz and 160 MHz?

Or it can be any value that we want?

rgds,

kc Wong

Hi Kiung,

Thanks for your patience.

I would suggest you to go ahead with the frequencies as mentioned in the table in the previous response.

Regards,

Vaibhav

The baud rate that we need is 3.125Mpbs. And that is requiring UART1 clock frequency to be 50MHz, but 50MHz does not seem to work, the M4F application just hang.

UART 16x mode: Divisor value = Operating frequency / (16 x baud rate)
1.0 = 50e6 / (16 * 3.125e6)

SOC_ModuleClockFrequency gSocModulesClockFrequency[] = {
    { TISCI_DEV_UART1, TISCI_DEV_UART1_FCLK_CLK, 50000000 },
    { TISCI_DEV_MCU_UART0, TISCI_DEV_MCU_UART0_FCLK_CLK, 48000000 },

    { SOC_MODULES_END, SOC_MODULES_END, SOC_MODULES_END },
};

It does not update the "gUartAttrs[]" in "ti_drivers_config.c" file, and it is fixed to 48MHz always. And by which requires a manual update by setting the "example.syscfg" to be excluded from the build.

/* UART atrributes */
static UART_Attrs gUartAttrs[CONFIG_UART_NUM_INSTANCES] =
{
    {
        .baseAddr           = CSL_UART1_BASE,
        .inputClkFreq       = 48000000U,
    },
    {
        .baseAddr           = CSL_MCU_UART0_BASE,
        .inputClkFreq       = 48000000U,
    },
};

Hi Kiung,

I have shared this concern with the developer and raised an internal JIRA to track this issue.

I will update you with further updates once I receive them.

Regards,

Vaibhav

Ok, thanks.

If it only supports a set of limited value, then may be a drop-down list like AM64x SysConfig will be good.

Else if it supports a range of value, then may be a little documentation of the valid clock frequency value will be helpful.

That would be my suggestions.

Hi Kiung,

Thanks for your response.

I have considered your inputs on the dropdown option or a guide on valid clock frequency value.

As said earlier, I will keep an eye on the JIRA and update you with activities on the same.

Thanks for your patience.

Regards,

Vaibhav

Hi Vaibhav,

Thanks for your update.

1. Also, I would like to suggest adding a new UART API to set baud rate.

2. And shouldn't be the "Read and throw Erroneous bytes from RxFIFO" code block checks for "while (0 != errorVal)" instead of checking the errorVal with all the error bits set??? I think it is a defect.

/mcu_plus_sdk_am62x_09_02_00_38/source/drivers/uart/v0/uart.h

static inline uint8_t UART_getCharFifo(uint32_t baseAddr, uint8_t *readBuf)
{
    uint8_t           readByte = 0;
    uint32_t          waitCount = UART_ERROR_COUNT;
    uint32_t          errorVal;
    uint32_t          lcrRegValue = 0;

    /* Preserving the current value of LCR. */
    lcrRegValue = HW_RD_REG32(baseAddr + UART_LCR);

    /* Switching to Register Operational Mode of operation. */
    HW_WR_REG32(baseAddr + UART_LCR, HW_RD_REG32(baseAddr + UART_LCR)
                            & 0x7FU);

    /* Read Rx Error Status */
    errorVal = HW_RD_REG32(baseAddr + UART_LSR) &
             (UART_LSR_RX_FIFO_STS_MASK |
              UART_LSR_RX_BI_MASK |
              UART_LSR_RX_FE_MASK |
              UART_LSR_RX_PE_MASK |
              UART_LSR_RX_OE_MASK);

    /* Restoring the value of LCR. */
    HW_WR_REG32(baseAddr + UART_LCR, lcrRegValue);

    /* Read and throw Erroneous bytes from RxFIFO */
    while ((UART_LSR_RX_FIFO_STS_MASK |
            UART_LSR_RX_BI_MASK |
            UART_LSR_RX_FE_MASK |
            UART_LSR_RX_PE_MASK |
            UART_LSR_RX_OE_MASK) == errorVal)
    {
        readByte = (uint8_t) (HW_RD_REG32(baseAddr + UART_RHR) & 0xFFU);
        waitCount--;
        if (0U == waitCount)
        {
            break;
        }

        /* Preserving the current value of LCR. */
        lcrRegValue = HW_RD_REG32(baseAddr + UART_LCR);

        /* Switching to Register Operational Mode of operation. */
        HW_WR_REG32(baseAddr + UART_LCR, HW_RD_REG32(baseAddr + UART_LCR)
                                & 0x7FU);

        /* Read Rx Error Status */
        errorVal = HW_RD_REG32(baseAddr + UART_LSR) &
                 (UART_LSR_RX_FIFO_STS_MASK |
                  UART_LSR_RX_BI_MASK |
                  UART_LSR_RX_FE_MASK |
                  UART_LSR_RX_PE_MASK |
                  UART_LSR_RX_OE_MASK);

        /* Restoring the value of LCR. */
        HW_WR_REG32(baseAddr + UART_LCR, lcrRegValue);
    }

    /* Read non-erroneous byte from RxFIFO */
    readByte = (uint8_t) (HW_RD_REG32(baseAddr + UART_RHR) & 0xFFU);

    return readByte;
}

rgds,

kc Wong

Hi Kiung,

Thank you for your response.

Kiung Chung Wong said:

1. Also, I would like to suggest adding a new UART API to set baud rate.

2. And shouldn't be the "Read and throw Erroneous bytes from RxFIFO" code block checks for "while (0 != errorVal)" instead of checking the errorVal with all the error bits set??? I think it is a defect.

I have taken your suggestions.

Please expect responses in sometime.

Regards,

Vaibhav

Greetings Kiung,

Thanks for your patience.

Vaibhav Kumar said:

I would like to suggest adding a new UART API to set baud rate.

I would like to comment on this line. If we talk about making anew API for setting UART Baud Rate, then there will be similar requests like creating a API to set frequency/interrupt/polled and so on, so currently we have taken your suggestion into account and we will consider to include the API based on MR.

Currently, I think the best approach would be to simply set it from SysConfig itself, given we are fixing the Frequency UART bug as well.

Vaibhav Kumar said:

And shouldn't be the "Read and throw Erroneous bytes from RxFIFO" code block checks for "while (0 != errorVal)" instead of checking the errorVal with all the error bits set??? I think it is a defect.

I would need to talk about this to a concerned dev, please expect to hear from me once I have confirmed its a bug.

Regards,

Vaibhav