USB cdc_acm questions

[AndyM]

Hello 

I have some questions about USB CDC ACM support under Zephyr

I need the shell on one CDC ACM device and to print print large chunks of data  to the console ( > 1024 bytes ) to another one

I am using cdc_acm_composite sample found in zephyr/samples

Questions

1, I was able to set up the shell to use the first cdc_acm device - that works fine. However the RTT log messages are also printed to the shell console -how do I get rid of them?

Obviously I need logging - but I just don't need to see the log messages in the shell, only in the RTT viewer. 
Here is my proj.conf file

CONFIG_LOG=y

CONFIG_UART_LINE_CTRL=y

CONFIG_UART_ASYNC_API=y

CONFIG_USB_DEVICE_STACK=y

CONFIG_USB_DEVICE_PRODUCT="Zephyr CDC ACM Composite sample"

CONFIG_USB_DEVICE_VID=0XABCD

CONFIG_USB_DEVICE_PID=0x0002

CONFIG_USB_COMPOSITE_DEVICE=y

CONFIG_SERIAL=y

# Redirect console to CDC

CONFIG_USB_SELF_POWERED=n

CONFIG_USB_WORKQUEUE=y

CONFIG_USB_WORKQUEUE_STACK_SIZE=1024

CONFIG_USB_WORKQUEUE_PRIORITY=-1

CONFIG_USB_CDC_ACM=y

CONFIG_USB_CDC_ACM_RINGBUF_SIZE=1024

CONFIG_SHELL_BACKEND_SERIAL_TX_RING_BUFFER_SIZE=1024

CONFIG_SHELL_BACKEND_SERIAL_INIT_PRIORITY=51

#Shell through COM port

CONFIG_SHELL=y

CONFIG_SHELL_BACKEND_SERIAL=y

CONFIG_SHELL_BACKENDS=y

What do I need to do to disable printing log messages to the cdc_acm device but still have them printed in the RTT log?

2. My main problem is with the second cdc_acm device where I need to print large chunks of data from my application

-If I use uart_poll_out - the newline characters are ignored in the console and everything appears on one line - tried CR, LF, CRLF

-If I use uart_fifo_fill -the new text is printed on the new line but not at the beginning of it - a number empty spaces printed before it

Also, the comment in the uart_fifo_fill declaration states
"This function is expected to be called from UART interrupt handler (ISR), if uart_irq_tx_ready() returns true.

 Result of calling this function not from an ISR is undefined (hardware-dependent)"

 Is it OK to call uart_fifo_fill from the application context on nRF52840?

If not - what's the right solution here?

Thank you

 

[Kenneth]

Try:

CONFIG_LOG_BACKEND_UART=n
CONFIG_LOG_BACKEND_RTT=y

Kenneth

[AndyM]

That did not help. I still see RTT log messages in the shell  console

Could you please provide answers to the other questions - about using uart_fifo_fill() and each new line printed at an offset like so

text 
      text

           text

Update

Did more testing

Apparently "\n" character at the end of the string causes the above behavior

"\r" character causes the current line to be overwritten so only the last line is printed. The cursor stays in the leftmost position

"\r\n" prints the lines correctly. 

I'm on Windows using putty

Thank you

[Kenneth]

AndyM said:

That did not help. I still see RTT log messages in the shell  console

I guess I should try this myself, but maybe you can try something like:

CONFIG_LOG=y
CONFIG_LOG_BACKEND_UART=n
CONFIG_LOG_BACKEND_RTT=y
CONFIG_USE_SEGGER_RTT=y
CONFIG_UART_CONSOLE=n
CONFIG_RTT_CONSOLE=y

AndyM said:

text 
      text

           text

Typicallly this is controlled by the terminal window, see New-line:

Kenneth

[AndyM]

I will test the config settings and let you know.

What about that comment in the uart_fifo_fill() function description?

It says that the function should only be used from an ISR. I'm using it from the main application thread  on an nRF52840 DK and don't see any ill effects. Simulated sending large data chunks and it seems to be working normally. Anything I'm overlooking here?

[AndyM]

Update

No luck with config settings. The log output still appears in the shell console

[AndyM]

Any updates? Thank you

[Kenneth]

It's not that much to say really, if I open the cdc acm composite example unmodifed and use:

CONFIG_LOG_BACKEND_UART=n
CONFIG_LOG_BACKEND_RTT=y

Then it prints to RTT, and similiar the following to UART:

CONFIG_LOG_BACKEND_UART=y
CONFIG_LOG_BACKEND_RTT=n

Edit: But when I enable Shell then I can see the log pops up. Let me look into it.

Kenneth