Linux/TMDSICE3359: UART4 Configuration

Vahagn Mkhitaryan14

Part Number: TMDSICE3359
Other Parts Discussed in Thread: AM3359

Tool/software: Linux

Dear all,

I am running Linux RT on AM3359 ICE v2 board.

I need to use UART connection in order to communicate with another device. I found in a link below that this board has UART4 RX and TX lines on connector J3.

http://processors.wiki.ti.com/index.php/AM335x_Industrial_Communication_Engine_EVM_Rev2_1_HW_User_Guide

However, I was not able to send or receive any data through this interface. Even when I try to use simple write (from Linux terminal I receive an error). I think I miss something out.

Belowthe is output of the from /proc/tty/driver/serial file. And as you can see UART 4 is not configured and has no driver. But I cant figure out how to do that.

root@am335x-evm:~# cat /proc/tty/driver/serial
serinfo:1.0 driver revision:
0: uart:unknown port:00000000 irq:0
1: uart:unknown port:00000000 irq:0
2: uart:unknown port:00000000 irq:0
3: uart:8250 mmio:0x481A6000 irq:30 tx:27571 rx:1068 RTS|CTS|DTR|DSR
4: uart:unknown port:00000000 irq:0
5: uart:unknown port:00000000 irq:0
6: uart:unknown port:00000000 irq:0
7: uart:unknown port:00000000 irq:0
8: uart:unknown port:00000000 irq:0
9: uart:unknown port:00000000 irq:0

Thanks in advance Vahagn M.

over 6 years ago

0 Pavel Botev over 6 years ago

TI__Guru**** 170625 points

Hi Vahagn,

In PSDK Linux-RT, only UART3 (used for console) is enabled in AM335x ICE DTS files. You need to enable UART4 in these files, you can check how UART3 is enabled and reuse the same approach for UART4.

linux-kernel/arch/arm/boot/dts/am335x-icev2.dts
linux-kernel/arch/arm/boot/dts/am335x-icev2-common.dtsi

&am33xx_pinmux {
uart3_pins_default: uart3_pins_default {
pinctrl-single,pins = <
AM33XX_IOPAD(0x934, PIN_INPUT_PULLUP | MUX_MODE1) /* (L17) gmii1_rxd3.uart3_rxd */
AM33XX_IOPAD(0x938, PIN_OUTPUT_PULLUP | MUX_MODE1) /* (L16) gmii1_rxd2.uart3_txd */
>;
};

&uart3 {
pinctrl-names = "default";
pinctrl-0 = <&uart3_pins_default>;
status = "okay";
};

Regards,
Pavel

0 Vahagn Mkhitaryan14 over 6 years ago in reply to Pavel Botev

Prodigy 100 points

Hi Pavel,
Thanks for help. As I understand I will need to rebuild kernel after that and make another sd card image??

0 Pavel Botev over 6 years ago in reply to Vahagn Mkhitaryan14

TI__Guru**** 170625 points

Vahagn,

Yes, kernel (zImage) and DTB (am335x-icev2.dtb). Refer to the below user guide:

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

Regards,
Pavel

0 Vahagn Mkhitaryan14 over 6 years ago in reply to Pavel Botev

Prodigy 100 points

Hi Pavel,

I was able to compile kernel and device tree file. After that, I replaced files on SD card with new ones.

When I tried to start Linux on the device. The following is log from the terminal. Can you please help me out on this one.

U-Boot 2018.01-g131dc82830 (Jul 25 2018 - 15:16:37 +0000)

CPU : AM335X-GP rev 2.1
Model: TI AM3359 ICE-V2
DRAM: 256 MiB
ETH0, CPSW
ETH1, CPSW
NAND: 0 MiB
MMC: OMAP SD/MMC: 0
*** Warning - bad CRC, using default environment

<ethaddr> not set. Validating first E-fuse MAC
Net: cpsw, usb_ether
Hit any key to stop autoboot: 0
switch to partitions #0, OK
mmc0 is current device
SD/MMC found on device 0
** Unable to read file boot.scr **
** Unable to read file uEnv.txt **
switch to partitions #0, OK
mmc0 is current device
Scanning mmc 0:1...
switch to partitions #0, OK
mmc0 is current device
SD/MMC found on device 0
6226432 bytes read in 631 ms (9.4 MiB/s)
37296 bytes read in 47 ms (774.4 KiB/s)
## Flattened Device Tree blob at 88000000
Booting using the fdt blob at 0x88000000
Loading Device Tree to 8df03000, end 8df0f1af ... OK

Starting kernel ...

0 Pavel Botev over 6 years ago in reply to Vahagn Mkhitaryan14

TI__Guru**** 170625 points

Vahagn,

refer to the below pointers:

e2e.ti.com/.../700251
e2e.ti.com/.../347095
e2e.ti.com/.../2546170

developer.ridgerun.com/.../Common_Problems_-_Linux_kernel_doesnt_boot

Regards,
Pavel

0 Pavel Botev over 6 years ago in reply to Pavel Botev

TI__Guru**** 170625 points

If you have no more questions related to the subject of this e2e thread, pelase close/verify/resolve this thread.

Regards,
Pavel

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Linux/TMDSICE3359: UART4 Configuration