The objective of this blog is to show you the steps necessary to use an existing Micrium OS USBD example and add CDC-ACM class and demo using the EFM32GG11.

Baseline Project

Since the Gecko SDK currently ships with a ‘micriumos_usbdhidmouse’ project for the SLSTK3701A_EFM32GG11 board, we can make a copy of it and rename it ‘micriumos_usbdcdcacm’. The convenience of making a copy of the project is to modify it according to our needs without breaking the Gecko SDK default projects.

Start by locating the ‘micriumos_usbdhidmouse’ folder in your Simplicity Studio installation. The project location is at ‘C:\SiliconLabs\SimplicityStudio\v4\developer\sdks\gecko_sdk_suite\v2.4\app\mcu_example\SLSTK3701A_EFM32GG11’

Once you found the folder, make a copy of it and rename it ‘micriumos_usbdcdcacm’. Please make sure to keep the new folder at the same path location of the original.

Locate the ‘SLSTK3701A_micriumos_usbdhidmouse.slsproj’  file inside your New Folder  ‘micriumos_usbdcdcacm\SimplicityStudio’ and rename it ‘SLSTK3701A_micriumos_usbdcdcacm.slsproj’ 

We will be adding our new workspace, so launch Simplicity Studio and connect the SLSTK3701A_EFM32GG11 board to the PC.

Add workspace by right-clicking anywhere inside the Project Explorer box and Select Import > MCU Project

Use the Browse button to locate the ‘SLSTK3701A_micriumos_usbdcdcacm.slsproj’ and click Next>

File location: 'C:\SiliconLabs\SimplicityStudio\v4\developer\sdks\gecko_sdk_suite\v2.4\app\mcu_example\SLSTK3701A_EFM32GG11\micriumos_usbdcdcacm\SimplicityStudio'

Since you already have your board connected, it should all be auto-detected. Leave everything by default making sure that there is an SDK selected, then click Next>

You can either change the name of the project or keep the default, then click Finish.

Configuration Files

 We will now need to modify the project configuration files in order to include Micrium OS USBD CDC-ACM class as part of our build.

Start by expanding the Includes section in the Project Explorer panel, then expand the configuration folder as shown in the image below. After that, double-click on the rtos_configuration.h to open it in the editor.

As soon as you try to edit the rtos_description.h, you will be presented a Warning indicating you are editing an SDK file. Click on Edit in SDK.

Add the following #define in rtos_description.h to indicate Micrium OS that you want to use CDC ACM class.

#define  RTOS_MODULE_USB_DEV_ACM_AVAIL
#define  RTOS_MODULE_USB_DEV_CDC_AVAIL

Remove the following #define in rtos_decription.h

#define  RTOS_MODULE_USB_DEV_HID_AVAIL

Tell Micrium OS you want to use the USBD CDC-ACM demo by modifying ex_description.h. Expand the Includes section in the Project Explorer panel, then expand the project folder as shown in the image below. After that, double-click on the ex_description.h to open it in the editor.

As soon as you try to edit the ex_description.h, you will be presented a Warning indicating you are editing an SDK file. Click on Edit in SDK.

Remove the following #define in ex_decription.h

#define  RTOS_MODULE_USB_DEV_HID_AVAIL

Add the following #define in ex_description.h to indicate Micrium OS that you want to use CDC-ACM class.

#define  RTOS_MODULE_USB_DEV_ACM_AVAIL

Adding USBD Class and Demo

Expand the src section in the Project Explorer panel and remove the ‘ex_usbd_hid_mouse.c’ linked file.

Select Import > MCU Project by right-clicking on src section as shown on image below

Choose ‘More Import Options…’  and select File System  on the next window that pops-up as shown on the images below

Use Browse button and add ‘ex_usbd_cdc_acm_terminal.c’ example as shown on image below, and click Finish.

File location: `C:\SiliconLabs\SimplicityStudio\v4\developer\sdks\gecko_sdk_suite\v2.4\app\micrium_os_example\usb\device\all`

Expand the usb>source>device>class section in the Project Explorer  panel and right-click on class. Select Import > MCU Project  and add the USBD CDC ACM class file as shown on images below

Use the Browse button to locate the CDC-ACM files to be added as shown below.

File location: `C:\SiliconLabs\SimplicityStudio\v4\developer\sdks\gecko_sdk_suite\v2.4\platform\micrium_os\usb\source\device\class`

Running the Example

You can now build your application and flash it on the board. Once the application starts running, you should see LED0 on the board blinking which means all the initialization was done correctly; therefore, we can now test the USBD CDC-ACM demo.

Open Windows Device Manager and expand the 'Ports (COM & LPT)' section. 

Use a Micro-USB B cable to connect the PC to the EFM32GG11 board. As soon as you connect it, Windows will enumerate the device and display it in 'Ports (COM & LPT)' as shown in the image below. Keep in mind that Windows is the one assigning the port number (COM7)  to my device.

Once you know the serial port number, we can use any serial terminal application and  open a terminal window.  The images below shows the terminal configurations and the CDC-ACM demo output.