Register Map
13-46
13.2.20
Endpoint 0 Configuration Register (EP0)
The read/write endpoint 0 configuration register (EP0) gives the device config-
uration for control endpoint 0.
Table 13–21. Endpoint 0 Configuration Register (EP0)
Bit
Name
Description
15–14
–
Reserved
13–12
EP0_Size
Endpoint 0 FIFO size
11
–
Reserved
10–0
EP0_ptr
Endpoint 0 pointer
13.2.20.1
Endpoint 0 FIFO Size (EP0_Size)
This field contains the endpoint 0 FIFO size value and must match the
value sent by the local host to the USB host during the GET_DEVICE_
DESCRIPTOR request preceding configuration phase. Status flags (the
Non_ISO_FIFO_Empty, the Non_ISO_FIFO_Full) and overrun/underrun con-
ditions are based on this value for all IN and OUT transactions to endpoint 0.
The local host must fill this field before setting the Cfg_Lock bit.
00: 8 bytes
01: 16 bytes
10: 32 bytes
11: 64 bytes
Value after local host reset is low (both bits), after USB reset is unchanged.
13.2.20.2
Endpoint 0 Pointer (EP0_ptr)
This field contains the address of the endpoint 0 pointer. Value 0x000 is forbid-
den (reserved for setup FIFO).
0x000: address = BASE (forbidden)
0x001: address = BASE + 8 bytes
0x002: address = BASE + 16 bytes
0x003: address = BASE + 24 bytes
...
0x0FF: address = BASE + 2040 bytes
Value after local host reset is low (all bits), after USB reset is unchanged.