Question, i.MX6 UART re-initialization

[Aemj]

Dear TIC team,

I would like to ask about re-initializing of i.MX6 UART.

My customer is using i.MX6S UART and they need to change UART settings in their application.

When they implemented the re-initialization software without disabling interrupt, they saw the UART did not work as expected after the re-init due to the behavior of interrupt.

Then they added disabling RX interrupt before the re-init process, and UART worked fine after the re-init.

Could you show me whether the adding disabling RX int right before the re-init is reasonable?

Thanks,

Miyamoto

[fabio_estevam]

Miyamoto,

Could you please tell which OS is your customer using and also:

- The exact steps to reproduce the problem?

- The patch with their fix

Thanks

[Aemj]

Hi Fabio,

OS: i-Tron base

Re-init procedure:

              HW_UART_UCR1_CLR(instance,BM_UART_UCR1_RRDYEN);      // disable UART RX interrupt

             uart_init( instance, baudrate, PARITY_NONE, stopbits, EIGHTBITS, FLOWCTRL_OFF );

              uart_set_FIFO_mode( instance, RX_FIFO, 1, IRQ_MODE );

Without the 1st step, disabling RX int, the re-init does not work fine.

Without disabling rx int, interrupt seems to occur repeatedly after the re-init.

the uart_init() function came from your SDK.

BR,

Miyamoto

[Aemj]

Hi Fabio,

The customer wants to clarify whether the disabling interrupt is needed when changing UART settings(baud-rate, stop-bit length change).

Do you think the disabling int is not needed always?

BR,

Miyamoto

[fabio_estevam]

Hi Miyamoto,

I thought initially your customer was using linux, but this issue I have never seen with linux.

I am not familiar with SDK or i-Tron OS, sorry.

Regards,

Fabio Estevam

[igorpadykov]

Hi AVNET JAPAN FAE

what UART bits they changed during "re-init process",

had UARTEN, RXEN changed?

Best regards

igor

[Aemj]

Hi Igor,

Baudrate and length of stop-bit were changed.

BR,

Miyamoto

[igorpadykov]

Hi AVNET JAPAN FAE

seems it may be caused below

Re: i.MX6 UART hardware misbehaves on baudrate mismatch

fixed if bit 7 of UCR3 (ADNIMP in the reference manual) is set.

Best regards

igor