topic UART Configuration in i.MX Processors

UART Configuration

deepanrajanbara — Mon, 01 Sep 2014 07:32:38 GMT

Hi,

Ours is a custom board based on imx6 SBC.we are to configure the UART3(not debug UART) with 4Mbps speed .Can Anyone please tell where to set the UART speed in u-boot and Linux Kernel.

Thankyou,

Deepanraj.A

Re: UART Configuration

igorpadykov — Wed, 03 Sep 2014 10:03:28 GMT

Hi Deepanraj

in Uboot you can try to set in uboot/include/configs/mx6q_sabresd.h

#define CONFIG_BAUDRATE

4000000

and check

Best regards

chip

Re: UART Configuration

deepanrajanbara — Wed, 03 Sep 2014 10:37:20 GMT

Hi,

I Have tried that but am not able to check its working in minicom or teraterm.which serial terminal is possible to check .

Thankyou

Re: UART Configuration

saurabh206 — Wed, 03 Sep 2014 11:30:40 GMT

Hi,

Deep

Use oscilloscope and check signals on pins.

Saurabh

Re: UART Configuration

igorpadykov — Wed, 03 Sep 2014 14:23:37 GMT

Hi Deepanraj

you can add debug printf to function serial_setbrg() in

uboot/drivers/serial/serial_mxc.c

to check what exact baudrate is set to UART:

void serial_setbrg (void)

{

u32 clk = mxc_get_clock(MXC_UART_CLK);

if (!gd->baudrate)

gd->baudrate = CONFIG_BAUDRATE;

__REG(UART_PHYS + UFCR) = 4 << 7; /* divide input clock by 2 */

__REG(UART_PHYS + UBIR) = 0xf;

__REG(UART_PHYS + UBMR) = clk / (2 * gd->baudrate);

}

Best regards

chip

Re: UART Configuration

alejandrolozan1 — Thu, 04 Sep 2014 14:38:46 GMT

Hi,

I would use an scope or a logic analyzer to check the baudrate. I am not sure if those serial terminals support that baudrate.

It might be possible that even the clock source needs to be changed. But please measure that before and let us know.

Best Regards,

Alejandro