CM3+ - Connecting LAN9512, but also get USB Slave functionality?

[Mahonroy]

Hello, I am designing a circuit board using the CM3+. I have pins USB_DP(165) and USB_DM(167) connected up to a LAN9512 for ethernet functionality..... but I also need to be able to connect a PC up to it and have it show up as a mass storage device for configuration (slave mode). In this case, you would typically run USB_DP(165) and USB_DM(167) directly to D+ and D- of a micro USB-B connector (not connected to LAN9512).

How do you have both? And how should the USB_OTGID (168) function in this case?

Thanks and any help or advice is greatly appreciated!

[plugwash]

The controller on the BCM283x can't be both a host and a device at the same time.

If you want both host and device functionality, but not at the same time, then you will need to use a USB mux IC, like the FSUSB42UMX used on the CMIO board triggered by the VBUS on the slave connector. You probablly also want to add a transitor to pull the OTG_ID pin low when using the port in host mode (they didn't bother on the CMIO since the device mode was only used for booting).

[fuwen0202]

I used a hub ic named fe2.1，then use lan9500 for lan

[Mahonroy]

Thanks for the info!
I am reading that the compute module (CM3) already has this FSUSB42UMX chip on-board is that correct? In that case I wouldn't need to put that in my circuit board?

[aBUGSworstnightmare]

Thanks for the info!
I am reading that the compute module (CM3) already has this FSUSB42UMX chip on-board is that correct? In that case I wouldn't need to put that in my circuit board?

no, it's on the CMIO --> you need to put in on your baseboard

[Mahonroy]

I looked up the schematic for the CMIO, and I found that it uses the FSUSB42UMX chip. So would I want to do it just like this, only instead of routing the "HOST" portion to a USB-Type A connector, to instead rout this to a LAN9512 chip, which will give me ethernet capability (and additional USB ports but I won't need them).

cm3_1.jpg (183.74 KiB) Viewed 1284 times

I also noticed this on the CMIO design, is this typically how you would want it to work?

cm3_2.jpg (182.37 KiB) Viewed 1284 times

Thanks again for the help!

[ag2000ir]

Correct, you can use the FSUSB chip as shown to switch between 2 modes.

[Mahonroy]

The controller on the BCM283x can't be both a host and a device at the same time.

If you want both host and device functionality, but not at the same time, then you will need to use a USB mux IC, like the FSUSB42UMX used on the CMIO board triggered by the VBUS on the slave connector. You probablly also want to add a transitor to pull the OTG_ID pin low when using the port in host mode (they didn't bother on the CMIO since the device mode was only used for booting).

The USB_OTGID pin was the only thing I couldn't quite figure out.

So when using the Ethernet in host mode, this should be low. If using the USB and having the device show up as a usb mass storage device, do I want to pull the USB_OTGID pin high? The manual says that if its fixed slave or fixed master to tie the pin to ground, so its a bit confusing.

[gsh]

Drive pin to ground for host mode (CM is a host and will talk to devices)
Open circuit pin (there is an internal pull-up to 1v8) for device mode (CM is a device and will respond to an external computer)