Getting ttyO2 and ttyO3 to work?

Hi Sean,

To check if everything is pinmuxed correctly, do the following:

mount -t debugfs none /sys/kernel/debug/
cat /sys/kernel/debug/omap_mux/spi0_sclk
cat /sys/kernel/debug/omap_mux/spi0_d0
cat /sys/kernel/debug/omap_mux/spi0_cd1
cat /sys/kernel/debug/omap_mux/ecap0_in_pwm0_out

These commands will show you how these pins are muxed.

Also note that the ecap0 pin is used in the gen_purp_evm_dev_cfg[], so please make sure you are not causing any conflicts.

A similar issue was answered here some time ago:

Miroslav Kiradzhiyski XID said:

I just tried Profile 3 on the AM335x EVM board and UART2 works fine. Please try to test UART2 using microcom instead of your application. Microcom is part of the busybox binary, which is included in the Arago filesystem, which is part of the official TI AM335x SDK.

Here are my steps:

On EVM board:

1. I switched to Profile 3 which uses UART0, UART1 and UART2.
2. I started the board (UART0 is used for serial console to the PC).
3. Start serial communication through UART2: microcom -s 115200 /dev/ttyO2

On my host PC:

1. Start serial communication with the board using picocom (you may use minicom or whatever you wish):
sudo picocom -b 115200 /dev/ttyUSB0 (I'm using a RS232 to USB converter - your port may be different)

Whatever you type at either end of the communication, it should appear at the other (no echo to the sender).

Best regards,
Miroslav

Hi Miroslav,

Thanks for the informed comments.  Today I got ttyO1 working in TTL loopback mode.  I am still having problems getting bytes received on ttyO2 and ttyO3 however.  In my current setup I have a test PC generating RS-485 traffic to the ttyO3 port.  This is converted to TTL seemingly OK by the line driver (looked at it on the CRO).  I never see any characters received on ttyO2 or ttyO3 however.

Debugfs settings for ttyO3 are:

root@arm:~# cat /sys/kernel/debug/omap_mux/ecap0_in_pwm0_out
name: ecap0_in_pwm0_out.uart3_txd (0x44e10964/0x964 = 0x0009), b NA, t NA
mode: OMAP_MUX_MODE1 | AM33XX_PULL_DISA
signals: ecap0_in_pwm0_out | uart3_txd | spi1_cs1 | NA | spi1_sclk | mmc0_sdwp | NA | gpio0_7

and the pinmux settings for the three ports are below.  What about pull-ups or pull-downs on the rxd lines, are they required?  Also do we need to set the slow slew control bits on these serial lines?

/* pin mix for SunDAC uart1 */
static struct pinmux_config sundac_uart1_pin_mux[] = {
        {"uart1_rxd", OMAP_MUX_MODE0 | AM33XX_INPUT_EN},
        {"uart1_txd", OMAP_MUX_MODE0},
        {NULL, 0},
};

/* Module pin mux for uart2 */
static struct pinmux_config uart2_pin_mux[] = {
        {"spi0_sclk.uart2_rxd", OMAP_MUX_MODE1 | AM33XX_INPUT_EN},
        {"spi0_d0.uart2_txd", OMAP_MUX_MODE1},
        {NULL, 0},
};

/* Module pin mux for uart3 */
static struct pinmux_config uart3_pin_mux[] = {
        {"spi0_cs1.uart3_rxd",  OMAP_MUX_MODE1 | AM33XX_INPUT_EN},
        {"ecap0_in_pwm0_out.uart3_txd", OMAP_MUX_MODE1},
        {NULL, 0},
};

I've also tried sending a direct 3.3V TTL level serial stream into the RX pin of ttyO5, but get nothing.  Is there some kind of hardware handshaking that needs to be disabled?  Why would it work on ttyO0 an ttyO1 and not the other ports?

Also where exactly is the serial driver for the AM3352?

TI please chime in,

One thing I notice is that in this diff it mentions enabling UART2

http://arago-project.org/git/projects/?p=linux-am33x.git;a=blobdiff;f=arch/arm/mach-omap2/omap_hwmod_33xx_data.c;h=61d6cbaf32e582e23a32f4398418500635b8d7b2;hp=f5b1786f71c03f5fb6aff9915bde1bb6c8be16c5;hb=94082f35882b7da6256c9609e17fa1047d9477c7;hpb=0987862149575e557d50b2fc0cce21e2c04a257b

Looking at

"arch/arm/mach-omap2/omap_hwmod_33xx_data.c"

I notice that the definition for uart5 seems to refer to uart1's DMA settings:

static struct omap_hwmod am33xx_uart5_hwmod = {
        .name           = "uart5",
        .class          = &uart_class,
        .clkdm_name     = "l4ls_clkdm",
        .mpu_irqs       = am33xx_uart5_irqs,
        .main_clk       = "uart5_fck",
        .sdma_reqs      = uart1_edma_reqs,
        .prcm           = {
                .omap4  = {
                        .clkctrl_offs   = AM33XX_CM_PER_UART4_CLKCTRL_OFFSET,
                        .modulemode     = MODULEMODE_SWCTRL,
                },
        },
        .slaves         = am33xx_uart5_slaves,
        .slaves_cnt     = ARRAY_SIZE(am33xx_uart5_slaves),
};

Is this correct or should there be a separate definition for UART5's DMA channels?  If so, what are the numeric values of the DMA channels for UART5?