USB 1.1 PHY
==========

Status
------
This core is done. It was tested with a USB 1.1 core I have written on
a XESS XCV800 board with a a Philips PDIUSBP11A transceiver.
I have NOT yet tested it with my USB 2.0 Function IP core.

Test Bench
----------
There is no test bench, period !  As I said above I have tested this core
in real hardware and it works just fine.

Documentation
-------------
Sorry, there is none. I just don't have the time to write it. I have tried
to follow the UTMI interface specification from USB 2.0.
'phy_mode' selects between single ended and differential tx_phy output. See
Philips ISP 1105 transceiver data sheet for an explanation of it's MODE
select pin (see Note below).
Currently this PHY only operates in Full-Speed mode. Required clock frequency
is 48MHz, from which the 12MHz USB transmit and receive clocks are derived.

RxError reports the following errors
  - sync errors
    Could not synchronize to incoming bit stream
  - Bit Stuff Error
    Stuff bit had the wrong value (expected '0' got '1')
  - Byte Error
    Got a EOP (se0) before finished assembling a full byteAll of those errors
    are or'ed together and reported via RxError.

Note
1) phy_tx_mode selects the PHY Transmit Mode
When phy_tx_mode is '0' the outputs are encoded as
	txdn, txdp
	 0	0	Differential Logic '0'
	 0	1	Differential Logic '1'
	 1	0	Single Ended '0'
	 1	1	Single Ended '0'

When phy_tx_mode is '1' the outputs are encoded as
	txdn, txdp
	 0	0	Single Ended '0'
	 0	1	Differential Logic '1'
	 1	0	Differential Logic '0'
	 1	1	Illegal State

See PHILIPS Transceiver Data Sheet for ISP1105, ISP1106 and ISP1107
for more details.

2) usb_rst Indicates a USB Bus Reset (this output is also or'ed with
   the reset input).

Misc
----
The USB 1.1 Phy Project Page is
httpwww.opencores.orgcoresusb_phy

To find out more about me (Rudolf Usselmann), please visit
httpwww.asics.ws


Directory Structure
-------------------
[core_root]
 
 +-doc                        Documentation
 
 +-bench--+                   Test Bench
         +-verilog           Verilog Sources
         +-vhdl              VHDL Sources
 
 +-rtl----+                   Core RTL Sources
         +-verilog           Verilog Sources
         +-vhdl              VHDL Sources
 
 +-sim----+
         +-rtl_sim---+       Functional verification Directory
                    +-bin   MakefilesRun Scripts
                    +-run   Working Directory
         
         +-gate_sim--+       Functional & Timing Gate Level
                            Verification Directory
                     +-bin   MakefilesRun Scripts
                     +-run   Working Directory
 
 +-lint--+                    Lint Directory Tree
        +-bin                MakefilesRun Scripts
        +-run                Working Directory
        +-log                Linter log & result files
 
 +-syn---+                    Synthesis Directory Tree
        +-bin                Synthesis Scripts
        +-run                Working Directory
        +-log                Synthesis log files
        +-out                Synthesis Output