Debug console on iMX283/iMX287

[SamGandhi]

We are starting a new design using iMX283. We need two I2C buses on this design. And I know one of the I2C bus signal are muxed, which means if I enable both I2C buses I will loose the Debug console.

Is there anything we will loose by not having Debug console?

For linux purpose we will move the console to one of the other UART.

Would appreciate a feedback on this design choice.

-Sam

[JamesRobinson]

Hi Mike and Matt,

We have a design that is using

J6 AUART0_CTS/AUART4_RX/DUART_RX/GPIO3_2 for debug Rx

J7 AUART0_RTS/AUART4_TX/DUART_TX/GPIO3_3 for debug Tx. 

Am I correct that I need to set the value of USE_ALT_DEBUG_UART_PINS to 01? 

Currently the I2C0 is the same as the EVK, but the hardware team have G5 and H5 which are usally the debug Tx/Rx as the ACC_INT1 and ACC_INT2. I almost wounder if it would be better to flip them and keep the Tx/Rx as default. 

Also is there a way to set this up without using the OTP bit's. I am very shy about setting something I can't change if I mess up.....

Thanks for the help,

James

[Matt_ng9]

Just to clear up any other potential confusion, it does not take place of AUART0, just the CTS and RTS pins of AUART0, which you probably won't use anyway.  But as Mike said, the pin mux configuration tool will help a lot for your planning. 

[iMxGuy]

Yes, that is correct. In our design we have two I2C ports and also have the debug UART enabled. It all depends on how you have your pin muxing setup. There is a pin muxing configuration design tool on the Freescale website in the imx28 section.

Sam Gandhi said:

Hello Matt,

Just want to make sure I understand "The debug port can also be configured at the AUART0_CTS/AUART0_RTS pins". This means the Application UART 0 can be used as Debug serial port is that right?

Are you referring to section 12.3.1 that refers to USE_ALT_DEBUG_UART_PINS? so if I set those bits as 01 , AUART0 becomes my debug port?

(Referring to i.MX28 Application Processor Reference manual, Rev 1, 2010 )

[SamGandhi]

Hello Matt,

Just want to make sure I understand "The debug port can also be configured at the AUART0_CTS/AUART0_RTS pins". This means the Application UART 0 can be used as Debug serial port is that right?

Are you referring to section 12.3.1 that refers to USE_ALT_DEBUG_UART_PINS? so if I set those bits as 01 , AUART0 becomes my debug port?

(Referring to i.MX28 Application Processor Reference manual, Rev 1, 2010 )

[Matt_ng9]

The debug port can also be configured at the AUART0_CTS/AUART0_RTS pins.  Can you use that option?

Keep in mind, you can change pin configuration at any time.  And once it goes into production you may not necessarily need debug capabilities.  So maybe you can start with a port configured for debug, and switch it to another purpose after you start using an AUART port.

And you very rarely if ever have to have the capability to send data to the i.MX28 over the debug uart, so worst case you might be able to configure one of the I2C SDA lines as the DUART_TX (as long as you don't need the i2c port before you can switch to an AUART).  If no clock is present on the I2C SCL line, then I think everything on the i2c bus will be fine.