STM32L073 Unable to connect as USB Device

[RSoen.1]

We have a design that uses USB CDC device. We have used this with no problems on the 192KB version of the STM32L073 but when we switched to the 128KB version we get a "device not recognized" from the host PC. Before I do a lot of troubleshooting I wanted to make sure there is no difference in USB functionality between the two devices. I believe the RAM size is the same...

Thanks

Rich

[Imen GH]

​Hello @RSoen.1​ ,

I recommend you to follow this article : https://community.st.com/s/article/FAQ-USB-device-not-recognized

Imen

[RSoen.1]

Thank you for the suggestion, it still won't connect with the heap size increased to 0x1000.

[RSoen.1]

I am changing the min heap size in STM32L073RBTX_FLASH.ld. When I change anything in the ioc file the value gets overwritten. Is there a better place to set the heap size in the STM32CubeIDE?

Thanks

[Imen GH]

Hello,

You can start working with USB example available under STM32CubeL0 package to identify what is going wrong in your case and confirm if the problem here seems related to the hardware or software environment.

So, I recommend you to have a look to  the example under the STM32Cube directory:

Repository\STM32Cube_FW_L0_V1.12.0\Projects\STM32L073Z-EVAL\Applications\USB_Device\CDC_Standalone

You can get inspired from this CDC Standalone application to confirm that device is working properly.

 Imen