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LAN8742 and USB virtual com port won't coexist?

MForb.1
Associate II

STM32H735 using the RMII interface to the LAN8742 PHY chip. Right out of the eval board schematic, and it seems to work. USB also implemented in the usual way....and it works, until we turn on the LAN support in X-CUBE-AZRTOS-H7. Then the middleware layer that supports USB_DEVICE goes away. It's grayed-out. Pins are still available.

MForb1_0-1729115428515.png 

MForb1_1-1729116233586.png

I haven't seen any references that would suggest these two subsystems can't operate at the same time. We often use the virtual com port for printf debugging purposes, so it's kind of annoying to have the com port disappear. I hotwired a UART output for now to keep the code development moving, but if anyone knows why these two can't both be enabled at the same time, it would be nice to understand it. There must be cases where you need to have both USB and Ethernet present on the same device.

MForb1_2-1729122729213.png

 

MForb1_3-1729122879230.png

The USB_DEVICE support goes away as soon as we turn on the middleware layer X-CUBE-AZRTOS-H7. That's what the demo board uses for Ethernet support. LWIP leaves USB_DEVICE still available, but we had a lot of trouble with LWIP on a previous project so we'd prefer not to use it. Any suggestions on how we might solve this?

2 REPLIES 2
Pavel A.
Evangelist III

Two options: 1. wait for ST to fix the problem; 2. Generate code for both options separately, then splice manually.

 

FBL
ST Employee

Hi @MForb.1 @Pavel A. 

If you would like to add USBX middleware, you need to uncheck ST USB library and enable the Azure stack by selecting proper software components from the pack. 

FBL_1-1732790107135.png

In high speed, you have conflict between ULPI pins and ETH.

FBL_0-1732790083084.png

In full speed, it is fully functional.

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