uart3 can't work on dm814x

sphone pan

I am trying to connect to bt modules on dm814x board using UART3 interface.

I try the cmd : "#echo 1111111111111111 >> /dev/ttyO0 ", oscilloscope can grasp signal from uart0-tx pin,

I try the cmd : "#echo 1111111111111111 >> /dev/ttyO3 ",but none signal oscilloscope can grasp from uart3-tx pin,

when boot board，the following msg print

omap_uart.0: ttyO0 at MMIO 0x48020000 (irq = 72) is a OMAP UART0
omap_uart.1: ttyO1 at MMIO 0x48022000 (irq = 73) is a OMAP UART1
omap_uart.2: ttyO2 at MMIO 0x48024000 (irq = 74) is a OMAP UART2
omap_uart.3: ttyO3 at MMIO 0x481a6000 (irq = 44) is a OMAP UART3
omap_uart.4: ttyO4 at MMIO 0x481a8000 (irq = 45) is a OMAP UART4
omap_uart.5: ttyO5 at MMIO 0x481aa000 (irq = 46) is a OMAP UART5

when i have the problem ,i try to fix it use following process,but it does not help.

#if 0
omap_up.uartclk = clk_get_rate(uart_clk);
#else
omap_up.uartclk = OMAP24XX_BASE_BAUD * 16;
#endif

uart pinmux config is ok on uboot,because i can grasp signal use oscilloscope when i send msg use uart3 on uboot

why I try the cmd : "#echo 1111111111111111 >> /dev/ttyO3 ",

but none signal oscilloscope can grasp from uart3-tx pin,

who can help me?

tks!

over 11 years ago

0 Pavel Botev over 11 years ago

TI__Guru**** 170625 points

Hello,

UART0 and UART3 works on different clocks, that might be the issue here. See the below e2e threads for more info:

http://e2e.ti.com/support/dsp/davinci_digital_media_processors/f/716/p/191218/712451.aspx#712451

http://e2e.ti.com/support/dsp/davinci_digital_media_processors/f/716/t/253307.aspx

See also the below wiki page, might be in help:

http://processors.wiki.ti.com/index.php/TI81xx_PSP_Porting_Guide#Using_different_UART_than_the_default_EVM_configuration_as_console

Regards,
Pavel

0 sphone pan over 11 years ago in reply to Pavel Botev

Prodigy 180 points

thanks Pavel Botev for you reply.

i have reference following 2 Forum to change uart3 functional clock from sysclk8_ck (192MHz) to sysclk10_ck (48 MHz),but it does not work.

http://e2e.ti.com/support/dsp/davinci_digital_media_processors/f/716/p/191218/712451.aspx#712451

http://e2e.ti.com/support/dsp/davinci_digital_media_processors/f/716/t/253307.aspx

The UART3 pins are muxed with UART0 pins on our board.And i try to set up to use UART0 pins as UART3 pins by:

 static struct omap_board_mux board_mux[] __initdata = {
        TI814X_MUX(UART0_DSRN, OMAP_MUX_MODE1), /* Set up pin as TXD */  
        TI814X_MUX(UART0_DCDN, OMAP_MUX_MODE1), /* Set up pin as RXD */

        /* More entries for other peripheral pins .... */

        { .reg_offset = OMAP_MUX_TERMINATOR },
 };

But when I check the uart0_dcdn &  uart0_dsrn val ,they are still  TI81XX_MUX_MODE5 ,is it right????

Uart3 still does not work,

please help me!

0 sphone pan over 11 years ago in reply to Pavel Botev

Prodigy 180 points

thanks Pavel Botev, for your answer, i fix the problem ,and uart3 can work now.

The way to make a fix for me was modify arch\arm\mach-omap2\devices.c

static void __init ti81xx_video_mux(void)

{

....................................

#if 0 //
omap_mux_init_signal("i2c2_scl_mux0",
TI814X_PULL_UP | TI814X_INPUT_EN);
omap_mux_init_signal("i2c2_sda_mux0",
TI814X_PULL_UP | TI814X_INPUT_EN);
#endif

.................

}

make sure pin mux setting is right to use UART0 pins as UART3 pins ,not i2c2

excuse my english is pool , ^_^

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uart3 can't work on dm814x