Michael Geer

MC9S08JM USB Assembly Code

Discussion created by Michael Geer on Jun 18, 2012
Latest reply on Jul 27, 2012 by RogerSchaefer

My project is written in 100% assembly.

I do not know C.

The CMXUSB_LITE demos are in C.

Does anyone have USB code in assembly?


It seems that you would need quite a few subroutines (or functions in C) to handle the "standard requests" to enable the USB device and have it "recognized" by the host.  These seem like "basic/general" subroutines that just send/receive data from the USB registers.  At this point though, I'm not even sure which registers do what, or store what USB information.  I'm assuming one is the "class" (HID, Mass Storage, etc.), and I also am confused as to how the "endpoint addresses" work.  This USB is much more complex than I assumed, BUT, it seems the subroutines needed for the initial "USB connecting/communicating" are basic, and then it is just flag polling to receive new information.  Any USB functionality in assembly code would be very helpful.