Question about the USB CDC ACM Example

RE: Question about the USB CDC ACM Example

ovrebekk — Thu, 17 Feb 2022 16:48:25 GMT

Hi Sami

Did you test the standard CDC only example?

Is this working well while the combined example is not?

Anyway please open a new ticket on this. The devzone system is not really designed to handle multiple problems in the same ticket.

As long as you mention my example I am sure it will be assigned to me ;)

Best regards
Torbjørn

RE: Question about the USB CDC ACM Example

Sami Ul Haq — Thu, 17 Feb 2022 05:34:50 GMT

Hi Torbjørn

Hello Sir, I hope this message finds you well. Sir, I have implemented MSC and CDC functionality as per your nice instruction listed in #usbd_msc_cdc_asm_hands_on.zip. When I compile my program, it shows me the Mass storage and also virtual COM port(which I am looking for) but the problem is that when I am trying to open the virtual COM port in putty it shows me an error as you can see in an attached picture. And one other issue is that after some time, both virtual COM Port and Mass Storage got disconnected on their own. I don't know what's the problem, Any help regarding this will be very appreciated.
I am using nRF5_SDK_17.0.2_d674dde and NRF52840.

Regards: SamiUlHaq

RE: Question about the USB CDC ACM Example

ovrebekk — Fri, 13 Mar 2020 10:38:35 GMT

Hi Ryan

These hands on examples are mostly one off examples made for a particular training session, and not considered official Nordic deliveries.

If you search for hands_on on the NordicPlayground github account you will find a couple, and my colleague Bjørn made a really good Bluetooth service tutorial some years ago that he put on his personal Github account:
https://github.com/bjornspockeli/custom_ble_service_example

It is important to note that many of these hands on examples are quite old, running on old SDK versions, and they are not actively maintained.

Best regards
Torbjørn

RE: Question about the USB CDC ACM Example

ryerye120 — Wed, 11 Mar 2020 20:56:40 GMT

Hi Torbjørn,

Thank you so much for the in depth response. The hands_on_solution's readme is really useful. Are there more of these readmes/hands_on_solutions?

Thanks,

Ryan

RE: Question about the USB CDC ACM Example

ovrebekk — Fri, 08 Mar 2019 08:41:51 GMT

Hi Jeff

Thanks for the patience and the kind words ;)

To save some time I didn't copy in all the fatfs functionality from the MSC example when I set up the project. I only copied the basic USB configuration and setup. This is probably the reason why you can't properly use the drives.

If you compare the main.c file to that of the usbd_msc example you will see that it runs some fatfs initialization code before the USB is initialized:

if (fatfs_init())
{
fatfs_ls();
fatfs_file_create();
}

Also, there are various function triggered by button presses for doing things like creating new files or listing the existing ones.

Please try to copy in this code from the example and see if it works as expected. If you are having issues with it just let me know, and I will take a look myself.

Best regards
Torbjørn

RE: Question about the USB CDC ACM Example

JeffW — Thu, 07 Mar 2019 21:19:09 GMT

Torbjørn,

Your thorough response is well worth the wait! :)

I was able to run the project you provided. It seems to show up as a COM port and USB MSC as expected. However, I had issues actually trying to use the file storage part of the application. The drive successfully mounted but I wasn't able to write files or open it the drive.

It may have been an issue on my side but, when I tried to implement the interface change you listed on my project previously posted, I came across the same results.

I would be very curious if that portion works on your end.

Thank you for your extended help,
Jeff

RE: Question about the USB CDC ACM Example

ovrebekk — Wed, 06 Mar 2019 12:31:36 GMT

Hi again

Apparently the problem with my example was a conflict with the interfaces. By changing the interface assigned to the MSC class from 0 to 2 I was able to get it to work:

DZ122153_190305_usbd_cdc_acm.zip

Can you please give my example a try and see if it enumerates successfully both the comport and the MSC drives?

There is a local git repo in the zip, so you can see the changes I have made from the original example.

Best regards
Torbjørn

RE: Question about the USB CDC ACM Example

ovrebekk — Wed, 06 Mar 2019 07:47:08 GMT

Hi Jeff

Sorry for the slow response, I was out in vacation for the last couple of weeks.

I tried adding the MSC class to the CDC example (rather than the opposite), but I still have similar issues. I will ask the developer to have a look at my code and see if he can spot the problem, and get back to you.

Best regards
Torbjørn

RE: Question about the USB CDC ACM Example

JeffW — Fri, 15 Feb 2019 13:41:48 GMT

Torbjørn,

I was eventually able to get it to enumerate as a com port but with an error.
Seemingly changing the APP_USBD_PID to 0x520D the device would allow a removable drive to show up, with no COM port.
But with APP_USBD_PID 0x520F it would enumerate a COM port with error: "This device cannot start. (Code 10)" and a secondary 'Other device': nRF52 USB MSC Demo that does not mount as a drive. Photo attached.

Maybe that's a clue, but I fail to understand how the Product ID would change this behaviour unless the underlying drivers are changing this behaviour.

Thank you for the input, looking forward to hearing back from a developer,
Jeff

RE: Question about the USB CDC ACM Example

ovrebekk — Fri, 15 Feb 2019 13:30:26 GMT

Hi Jeff

Are you not seeing the virtual comport at all?

For me it shows up, but I get an error when I try to connect to it.

I looked through your code and tried to figure out what the problem is, but I can't see any critical difference between the original example and yours.

I will try to get some feedback from the developer if he has some pointers.

Best regards
Torbjørn

RE: Question about the USB CDC ACM Example

JeffW — Thu, 14 Feb 2019 13:07:17 GMT

Made a fresh project from usbd_msc included.
The other change I noticed is needing the inclusion of:

// <q> APP_USBD_CDC_ACM_ENABLED  - Enabling USBD CDC ACM Class library
 

#ifndef APP_USBD_CDC_ACM_ENABLED
#define APP_USBD_CDC_ACM_ENABLED 1
#endif

// <q> APP_USBD_CDC_ACM_ZLP_ON_EPSIZE_WRITE  - Send ZLP on write with same size as endpoint
 

// <i> If enabled, CDC ACM class will automatically send a zero length packet after transfer which has the same size as endpoint.
// <i> This may limit throughput if a lot of binary data is sent, but in terminal mode operation it makes sure that the data is always displayed right after it is sent.

#ifndef APP_USBD_CDC_ACM_ZLP_ON_EPSIZE_WRITE
#define APP_USBD_CDC_ACM_ZLP_ON_EPSIZE_WRITE 1
#endif

Attached is the project. Note: I used Segger Embedded Studio.

Thanks,
Jeff
devzone.nordicsemi.com/.../usbd_5F00_msc_5F00_cdc.zip

RE: Question about the USB CDC ACM Example

JeffW — Thu, 14 Feb 2019 12:36:55 GMT

Yes, CDC works on it's own.
SDK15.2 SD 6.1 with PCA10056 V1.0.0

The only difference in porting as per your word document was:

 APP_USBD_CDC_ACM_GLOBAL_DEF(m_app_cdc_acm,
                            cdc_acm_user_ev_handler,
                            CDC_ACM_COMM_INTERFACE,
                            CDC_ACM_DATA_INTERFACE,
                            CDC_ACM_COMM_EPIN,
                            CDC_ACM_DATA_EPIN,
                            CDC_ACM_DATA_EPOUT,
                            APP_USBD_CDC_COMM_PROTOCOL_AT_V250);

instead of:

#define CDC_ACM_INTERFACES_CONFIG()                 \
    APP_USBD_CDC_ACM_CONFIG(CDC_ACM_COMM_INTERFACE, \
                            CDC_ACM_COMM_EPIN,      \
                            CDC_ACM_DATA_INTERFACE, \
                            CDC_ACM_DATA_EPIN,      \
                            CDC_ACM_DATA_EPOUT)


static const uint8_t m_cdc_acm_class_descriptors[] = {
        APP_USBD_CDC_ACM_DEFAULT_DESC(CDC_ACM_COMM_INTERFACE,
                                      CDC_ACM_COMM_EPIN,
                                      CDC_ACM_DATA_INTERFACE,
                                      CDC_ACM_DATA_EPIN,
                                      CDC_ACM_DATA_EPOUT)
};

/**
 * @brief CDC_ACM class instance
 * */
APP_USBD_CDC_ACM_GLOBAL_DEF(m_app_cdc_acm,
                            CDC_ACM_INTERFACES_CONFIG(),
                            cdc_acm_user_ev_handler,
                            m_cdc_acm_class_descriptors
);

Is it possible to take a look at this with the new SDK to see if i'm missing something?
I will try to upload a project in a few minutes.

Regards,
Jeff

RE: Question about the USB CDC ACM Example

ovrebekk — Thu, 14 Feb 2019 08:47:13 GMT

Hi Jeff

Have you got the CDC_ASM example to work on its own?

Can you let me know what version of the nRF52840 DK you have?

Best regards
Torbjørn

RE: Question about the USB CDC ACM Example

JeffW — Wed, 13 Feb 2019 20:42:13 GMT

Torbjørn,

I am trying to get this example to work using SDK 15.2, however the COM port does not enumerate after following your instructions of adding CDC onto the existing MSC example. The MSC part works, but the COM port does not initialize even though no errors show up while the application is running. I have tried in two different projects, with the same result.

Any help would be appreciated.

Thanks,
Jeff

RE: Question about the USB CDC ACM Example

ovrebekk — Tue, 12 Feb 2019 09:40:39 GMT

Hi again

There is no plan to add a CDC_ACM backend to the LOG module unfortunately, but the developer pointed me to a different solution:

It is possible to use the CLI module for logging rather than the normal log backends, and the CLI module has a CDC_ACM backend.

In other words if you first switch to using the CLI module for logging then you should be able to get logging running over CDC.

Best regards
Torbjørn

RE: Question about the USB CDC ACM Example

ovrebekk — Mon, 11 Feb 2019 13:24:04 GMT

The supported backends for the LOG module is UART, RTT and flash. USB_CDC is not supported unfortunately.

I can check with the software team if we are planning to add support for this in a later update.

Best regards
Torbjørn

RE: Question about the USB CDC ACM Example

ratnakar1978 — Tue, 05 Feb 2019 05:33:41 GMT

Hi Torbjorn, I am able to flash the program with debug USB port on the EVK but I am not able to get LOG information back to host PC (on putty prompt) . Even I tried to connect with USB connector closer to Nordic chipset , but I am not able to get log data from EVK nor from chipset to host PC . Can you please share any example or configuration do I need to do in the application for getting NRF_LOG works fine on USB interface.

RE: Question about the USB CDC ACM Example

ovrebekk — Thu, 19 Apr 2018 10:26:38 GMT

This example has not been updated to SDK v15, no.

Have you tried opening the MSC example in SDK v15 and following the instructions provided in usbd_msc_cdc_asm_hands_on.zip?

Best regards
Torbjørn

RE: Question about the USB CDC ACM Example

Panchen — Wed, 18 Apr 2018 14:04:11 GMT

I can not compile usbd_msc_cdc_asm_hands_on_solution.zip in SDK15.0.0. Do you have any updated file?

RE: Question about the USB CDC ACM Example

ovrebekk — Tue, 23 May 2017 07:21:01 GMT

My bad, I forgot the repo was private. I have attached the files in my original reply.
BR, Torbjørn

RE: Question about the USB CDC ACM Example

MANGO — Tue, 23 May 2017 07:00:12 GMT

Hello, Torbjørn. Wow, a hands on example, I'm deeply touched!

Although that GitHub link shows a 404 error, I will check the code soon.

Thanks for your time.

-Best Regards, MANGO

RE: Question about the USB CDC ACM Example

ovrebekk — Tue, 23 May 2017 06:47:16 GMT

Hi Mango

I made a hands on example showing you how to combine MSC and CDC a while back, and put it on github: CDC MSC hands on
I never got past the first task, but this is what you need (combining two USB classes into one example).
No, my point was that the MSC example essentially shows of two things:

We finally have USB support in the 52 family, and MSC is supported.
We have a new QSPI interface in the 52840 that is very well suited to connecting external memory chips.
Best regards
Torbjørn

RE: Question about the USB CDC ACM Example

MANGO — Fri, 19 May 2017 09:23:33 GMT

Wow. Thanks for the detailed answer, Torbjørn!

If you want to transfer files you should probably consider the MSC examples instead

Then can I use both MSC example and CDC ACM example?

I want to both send UART data (or ASCII data packets, maybe?) to the connected PC

and receive files from the PC with the single nRF52840 chip by merging both examples.

Is this possible?

showcasing the new QSPI interface in the chip

You mean there was a video demo that used QSPI?

The infocenter tells that The nRF52840 Preview DK board has a 64-Mb external flash memory. The memory is a multi-I/O memory supporting both regular SPI and Quad SPI. and this feature might be the thing I was looking for.

-Best Regards, MANGO

RE: Question about the USB CDC ACM Example

ovrebekk — Fri, 19 May 2017 08:14:42 GMT

Hi Mango

Yes. The USB interface in the nRF52840 allows it to implement FT232 like functionality without any additional hardware.
Since the USB interface is fully programmable it can also do a lot more, as you can see by all the different USB examples available in the SDK.
Just keep in mind that you need to connect to the second USB connector on the nRF52840 PDK to get access to the Nordic USB interface, otherwise you are just connecting to the Segger programming chip. From your terminal program the comport should look like any other, yes, and both read and write is supported.
The USB interface has dedicated pins that are separate from the standard GPIO ports, and they can not be relocated to any other pins. The reason for this is that the USB interface pins require dedicated hardware that would be expensive and impractical to duplicate on multiple pins.

The physical UART is only used for logging in this example, and the default configuration of UART0 (which allows it to connect to the UART interface in the Segger chip) is printed on the back of the nRF52840 PDK. This is the same configuration that we have always used, even before we got USB support in the chip, and it uses the CDC ACM functionality of the Segger chip to make the UART available on the PC.

If you want to connect the Nordic CDC interface to a physical UART you could potentially use UART1 for this, allowing you to keep using UART0 for logging and debugging purposes.

The J-Link USB connector is only used for programming/debugging and logging. To connect to the CDC in the Nordic you should add a second USB connection to the USB connector on the side of the kit, closer to the Nordic chip. You can connect both at the same time, or just connect to the Nordic connector (if you don't need logging or debugging).

Regarding the layout you should refer to the reference schematic.
As you can see the VBUS, D+ and D- lines should just be connected directly to the connector.

If you want to transfer files you should probably consider the MSC examples instead, as they make the nRF52840 enumerate as a disk drive on the PC side. By default the example is configured to use the external memory chip on the nRF52840 PDK to store the files (showcasing the new QSPI interface in the chip), but it can also be configured to store to an external SD card.

Edit: I have attached the CDC MSC hands on examples here:
usbd_msc_cdc_asm_hands_on.zip
usbd_msc_cdc_asm_hands_on_solution.zip

Best regards
Torbjørn