Comments on: Lightweight USB Host. Part 3 – accessing MAX3421E.

By: Richard

Richard — Sun, 08 Nov 2009 22:47:07 +0000

The hub is a fairly simple device and described well in the USB specification. Basically you enumerate the hub first and allocate it an address. You can then communicate with the hub to enable ports and enumerate in turn if a device is present. Once all enumerated and addressed you can talk to each device direct simply by address.

I do not have any MAX3421E code for this, but have implemented on SL811HS. In fact I recall the SL811HS development kit software does have an code example if you can find it.

The MAX3421E does have advantage over some more “intelligent” processors when using a hub because the processor has more direct control over multiple devices and endpoints.

Note that multiple devices means lots more endpoints and so greater demand on program and data memory. If as you suggest you wish to use mutiple mass storage devices, you will need at least a large AtMega or better processor with more RAM to support the multiple mass storage protocol layers and likely FAT too.

By: Max

Max — Sun, 08 Nov 2009 17:14:07 +0000

quote from oleg”However, you still need a piece of code to communicate to the hub to enumerate it and learn about physical bus events like device connect/disconnect to the downstream ports, and send bus resets out the hub ports. Such piece of code is not that hard to develop; hub communications were designed to be very simple.”

where can I get sample codes for USB hub? I also need this piece of code to be able to use multiple devices.

By: oleg

oleg — Wed, 01 Jul 2009 21:23:08 +0000

Any USB host is only capable of connecting to a single device, that’s in the standard. USB Hub is just a device which makes communication between host controller and devices connected to the hub transparent. However, you still need a piece of code to communicate to the hub to enumerate it and learn about physical bus events like device connect/disconnect to the downstream ports, and send bus resets out the hub ports. Such piece of code is not that hard to develop; hub communications were designed to be very simple.

By: Danny

Danny — Wed, 01 Jul 2009 08:51:48 +0000

Hi,

Can I physicallay interface the MAX3421E USB Host Controller IC to a 4-Port-USB-HUB so that MCU can access to 4 USB Devices (4 thumbdrive) ?

OR the MAX3421e can only connect to only one downstream USB Devices like in the case of PIC32’s internal embedded USB host OTG.

Thanks.

Rgds,
Danny