topic Re: MX6UL UART2 RXProblem in i.MX Processors

MX6UL UART2 RXProblem

nachodiz — Tue, 22 Aug 2017 10:18:36 GMT

Dear all

UART2 from our custom MX6UL board is attached to a RN4871 Bluetooth Module

UART2 TX works fine but RX is not working

How can i configure uart2 rx properly?

King Regards

Re: MX6UL UART2 RXProblem

Yuri — Wed, 23 Aug 2017 03:23:06 GMT

Hello,

Please check (and modify if needed) under Linux :
1) IOMUXC_SW_MUX_CTL_PAD_UART2_RX_DATA register (0x20E_0098) :
if bit field mux_mode = 0.
2) IOMUXC_UART2_RX_DATA_SELECT_INPUT ( 0x20E_062C) :
if bit field DAISY = 01.

You may use memtool utility, located in /unit_tests directory of NXP BSP.

Have a great day,
Yuri

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Re: MX6UL UART2 RXProblem

Yuri — Thu, 24 Aug 2017 02:53:34 GMT

Hello,

Please read the dtb (as is, in binary) from the board and send me.

Regards,

Yuri.

Re: MX6UL UART2 RXProblem

Yuri — Fri, 25 Aug 2017 04:59:10 GMT

Hello, nachodiz !

from Your dtb configuration for UART2 :

serial@021e8000 {
compatible = "fsl,imx6ul-uart", "fsl,imx6q-uart", "fsl,imx21-uart";
reg = <0x21e8000 0x4000>;
interrupts = <0x0 0x1b 0x4>;
clocks = <0x1 0xbf 0x1 0xc0>;
clock-names = "ipg", "per";
dmas = <0x7 0x1b 0x4 0x0 0x7 0x1c 0x4 0x0>;
dma-names = "rx", "tx";
status = "okay";
pinctrl-names = "default";
pinctrl-0 = <0x37>;
fsl,uart-has-rtscts;
};

First - RTS/CTS is not used on Your scheme, therefore line "fsl,uart-has-rtscts;"

should be removed. Further - DMA cannot be used without RTS/CTS, so lines "dmas"

and "dma-names" should be removed too. You may try enclosed dtb file.

Note - high speeds cannot be used without DMA.

Regards,

Yuri.

Re: MX6UL UART2 RXProblem

stevenyu — Wed, 24 Jan 2018 11:03:52 GMT

Dear Yuri,

Recently, we use i.mx6ull and try to enable UART5, and then initialize it to be RS-232.

We can have TX working by echo "hello" > /dev/ttymxc4, and the "hello" will be show on PC console.

However, the RX path from PC console to i.mx6ull does not work.

We want to try the comment you mentioned. Would you please advise where can we configure these two parameters ?

IOMUXC_SW_MUX_CTL_PAD_UART2_RX_DATA / IOMUXC_UART2_RX_DATA_SELECT_INPUT

1) IOMUXC_SW_MUX_CTL_PAD_UART2_RX_DATA register (0x20E_0098) :
if bit field mux_mode = 0.
2) IOMUXC_UART2_RX_DATA_SELECT_INPUT ( 0x20E_062C) :
if bit field DAISY = 01.

Do you have any experience to configure UART on i.mx6ul to be RS-232/RS-485 ?

Regards,

Steven Yu