UART serial downloader settings

[ko-hey]

Hi all

I'm planning to use UART serial downloader with i.MX6UL.

I understand using USB_OTG port is easier than using UART port.

But, unfortunatlly, my customer's board doesn't have USB_OTG port.

So we have to try UART serial downloader and please advise me.

Add info:

I know EVK only support USB_OTG serial downloader from following thread.

https://community.nxp.com/thread/430063

https://community.nxp.com/thread/397195

1.

Is there any reference schematic to use UART serial downloader with i.MX6UL ?

2.

If there are no reference schematic, please tell me following question.

2-1 Which pins do I uset for using UART serial downloader ?

2-2 How to connnect the pins ?

2-3 What register configuration is correct ?

Ko-hey

[Yuri]

Hello,

   Please look at my comments below.

1.

Yes, USB Loader requires RTS/CTS for USB/UART converter.

2.

> Furthermore, if user remove the function of checking RTS and CTS signals
> from iMX USB Loader, user don't need those signals.

This is not obvious - it depends on application and USB/UART converter.

Regards,

Yuri.

[igorpadykov]

Hi Ko-hey

for description of UART serial downloader mode

please refer to Figure 8-2. Serial Download Boot Flow

sect.8.9.2 UART, sect.8.9.2.3 IOMUX Configuration for UART

i.MX6UL Reference Manual

http://cache.freescale.com/files/32bit/doc/ref_manual/IMX6ULRM.pdf

Best regards

igor

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[ko-hey]

Hi Igor

Thank you for reply.

I have to answer those question quickly because building process for their custom board have stopped due to this problem.

Could you answer following questions as soon as possible ?

I want to talk in the case of using UART1 and confirm all we have to do for UART serial downloader.

1. settings for serial download

1-1

User must set BOOT_MODE[1:0] to "01".

This refers to Table 8-1 of RM.

1-2

User must set WDOG_ENABLE to "1".

This refers to chapter 8.2.4 of RM.

1-3

User must set UART Serial Download Disable fuse (Fuse address is 0x470[3]) to "0".

This refers to Table 8-40 of RM.

2. external signal selection

Let me talk in the case of using UART1.

Is the following understanding correct ?

User can select either GPIO1_IO06 and UART1_CTS_B for UART1_CTS_B signal.

User can select either GPIO1_IO07 and UART1_RTS_B for UART1_RTS_B signal.

User can select only UART1_RX_DATA pad for UART1_RX_DATA pad.

User can select only UART1_TX_DATA pad for UART1_TX_DATA pad.

3. Pad control register settings

Let me talk in the case of using UART1.

The following register settings are up to customer. Is it correct ?

Do you have any reference for it ?

IOMUXC_SW_PAD_CTL_PAD_UART1_CTS_B or IOMUXC_SW_PAD_CTL_PAD_GPIO1_IO06

IOMUXC_SW_PAD_CTL_PAD_UART1_RTS_B or IOMUXC_SW_PAD_CTL_PAD_GPIO1_IO07

IOMUXC_SW_PAD_CTL_PAD_UART1_TX_DATA

IOMUXC_SW_PAD_CTL_PAD_UART1_RX_DATA

4. How to detect UART activity ?

How to detect UART activity after "Poll UART 1/2" ?

According to the serial download boot flow (Figure 8-2), it'll detect something after "Poll UART 1/2".

What activity does i.MX check ?

Is it register or other activities which are from external device ?

ko-hey

[igorpadykov]

Hi Ko-hey

only UART1_TX_DATA.alt0, UART1_RX_DATA.alt0, no rts/cts

signals are needed. Also pad control register settings are not

needed (default can be used). ROM checks UART USR1 RRDY bit

to check activity.

Best regards

igor

[ko-hey]

Hi Igor

We don't have to do anything for following register.

Is it correct ?

1-1

User must set BOOT_MODE[1:0] to "01".

This refers to Table 8-1 of RM.

1-2

User must set WDOG_ENABLE to "1".

This refers to chapter 8.2.4 of RM.

1-3

User must set UART Serial Download Disable fuse (Fuse address is 0x470[3]) to "0".

This refers to Table 8-40 of RM.

Ko-hey

[igorpadykov]

Hi Ko-hey

yes this is right

Best regards

igor

[ko-hey]

Hi Igor

Let me confirm about rts/cts signals.

I got answer that i.MX6UL uses RTS/CTS for UART serial download from Yuri.

Please check a following thread.

Want to serial download from UART of MCIMX6UL-EVK

Which is correct ?

Does i.MX6UL need RTS/CTS signals for UART serial download ?

Ko-hey

[Yuri]

Hello,

RTS/CTS should be used with UART/USB converter for USB_loader application.

The i.MX6 UART bootloader in itself does not use  RTS/CTS.

Regards,

Yuri.

[ko-hey]

Hi Yuri

Thank you for reply.

Let me confirm about following question.

1.

User need RTS and CTS when user use i.MX USB Loader ​ as reference.

Because the application check RTS and CTS.

Is it correct ?

Furthermore, if user remove the function of checking RTS and CTS signals from iMX USB Loader, user don't need those signals.

Is it correct ?

2.

i.MX6UL don't need RTS and CTS for UART serial download.

So if user make their own loader application without checking RTS and CTS signals, they don't need RTS and CTS signals.

Ko-hey

[ko-hey]

Hi Igor

Thank you for your cooperation.

I'll try it.

Ko-hey