doom_riscv/cores/usb/doc/mem-map.md

iCE40 USB Core Memory Map

Global CSRs

Control / Status (Read / Write addr 0x00)

,---------------------------------------------------------------,
| f | e | d | c | b | a | 9 | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 |
|---------------------------------------------------------------|
| p |evt| cs| ce|bsa|bra|brp|sfp| m |          addr             |
'---------------------------------------------------------------'

• p : Enables DP pull-up
• evt : Event pending
• cs : Control Endpoint Lockout - State [Read Only]
• ce : Control Endpoint Lockout - Enable
• bsa : Bus Suspend Asserted
• bra : Bus Reset Asserted
• brp : Bus Reset Pending
• sfp : Start-of-Frame Pending
• m : Enable address matching
• addr: Configure address matching

Action ( Write addr 0x01 )

,---------------------------------------------------------------,
| f | e | d | c | b | a | 9 | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 |
|---------------------------------------------------------------|
|  rsvd | cr|     /     |brc|sfc|               /               |
'---------------------------------------------------------------'

• cr : Control Endpoint Lockout - Release
• brc: Bus Reset Clear
• sfc: Start-of-Frame Clear

Events (Read addr 0x02)

This contains info about the generated events from the transaction microcode.

It can either contain info about the last event only along with a count of events since last read, or it can be a FIFO depending on the core configuration.

Count mode (EVENT_DEPTH = 0/1) :

,---------------------------------------------------------------,
| f | e | d | c | b | a | 9 | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 |
|---------------------------------------------------------------|
|      cnt      |                 event                         |
'---------------------------------------------------------------'

• cnt: Counter of events since last read
• event: Last recorded event data (see below)

FIFO mode (EVENT_DEPTH > 1) :

,---------------------------------------------------------------,
| f | e | d | c | b | a | 9 | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 |
|---------------------------------------------------------------|
| v | o |  rsvd |                 event                         |
'---------------------------------------------------------------'

• v: Valid (i.e. FIFO is not empty and event is valid)
• o: FIFO Overflow
• event: event data (see below)

Event format:

,-----------------------------------------------,
| b | a | 9 | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 |
|-----------------------------------------------|
|     ucnc      |      endp     | d | s | b | / |
'-----------------------------------------------'

• ucnc: Notification code
• endp: Endpoint #
• d: Direction (1=IN, 0=OUT/SETUP)
• s: Is SETUP ?
• b: Buffer Descriptor index

EP Status

Address:

,-----------------------------------------------,
| b | a | 9 | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 |
|-----------------------------------------------|
| 1   0   0   0 |     ep_num    |dir| 0   0   0 |
'-----------------------------------------------'

Data:

,---------------------------------------------------------------,
| f | e | d | c | b | a | 9 | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 |
|---------------------------------------------------------------|
|                               | t | b |  bdm  |   |  EP type  |
'---------------------------------------------------------------'

• t: Data Toggle (if relevant for EP type)
• b: Buffer Descriptor index
• 'bdm': Buffer descriptor mode
  • 00 - Single Buffer (index 0 only)
  • 01 - Double Buffer
  • 10 - Special Control EP mode (index 0=data, 1=setup)
• EP Type: (h indicates if this EP is halted)
  • 000: Non-existant
  • 001: Isochronous
  • 01h: Interrupt
  • 10h: Bulk
  • 11h: Control

Buffer Descriptor

Address:

,-----------------------------------------------,
| b | a | 9 | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 |
|-----------------------------------------------|
| 1   0   0   0 |     ep_num    |dir| 1 | i | w |
'-----------------------------------------------'

• i: BD Index (0/1)
• w: Word select

Word 0:

,---------------------------------------------------------------,
| f | e | d | c | b | a | 9 | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 |
|---------------------------------------------------------------|
|   state   | s |  rsvd |           Buffer Length               |
'---------------------------------------------------------------'

• s: Transactions was setup
• BD State:
  • 000: Empty / Unused
  • 010: Valid, ready for Tx/RX data
  • 011: Valid, issue STALL (and drop data)
  • 100: Used - Success
  • 1xx: Used - Error with xx=01/10/11 error code

Word 1:

,---------------------------------------------------------------,
| f | e | d | c | b | a | 9 | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 |
|---------------------------------------------------------------|
|       (rsvd)      |             Buffer Pointer                |
'---------------------------------------------------------------'