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

iCE40 USB Core Memory Map

Global CSR

Control (Write addr 0x000)

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

• p: Enables DP pull-up
• a: Ack interrupt

Status (Read addr 0x000)

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

This contains info about the last generated notification from the transaction microcode

• cnt: Counter (incremented by 1 at each notify to detect misses)
• ucnc: Notification code
• endp: Endpoint #
• d: Direction (1=IN, 0=OUT/SETUP)
• s: Is SETUP ?
• b: Buffer Descriptor index
• i: Interrupt flag

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
  • 01s: Interrupt
  • 10s: Bulk
  • 11s: 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               |
'--------------------------------------------------------------'