NEC Network Controller uPD98502 - Manual (Page 325)

CHAPTER 6 USB CONTROLLER
Preliminary User’s Manual S15543EJ1V0UM 325
6.2.15 U_CMR (USB Command Register)
This register is used for issuing Tx request or adding Rx Buffer Directories to Pool.
The V
R
4120A writes commands into this register.
Whenever B bit (Bit 31) is set, the value will not change even if the V
R
4120A writes commands into this register.
Bits Field R/W Default Description
31 B R/W 0 Busy:
Bit that indicates whether the interpretation of an issued command has
terminated. When the execution of the command has not yet completed, this
bit will be set to a ‘1’. When the execution of a command has completed, this
bit will be set to a ‘0’.
When the V
R
4120A tries to issue one command immediately after another, it
is necessary to confirm that this bit is set to a ‘0’.
30:27 Reserved R/W 0 Reserved for future use. Writes ‘0’s.
26:24 Command R/W 000 Field for specifying the type of a command. USB Controller's internal
processing varies depending on the value written into this field.
000: Data transmitting at EndPoint0
001: Data transmitting at EndPoint1
010: Data transmitting at EndPoint3
011: Data transmitting at EndPoint5
100: Addition of Buffer Directories to Pool0
101: Addition of Buffer Directories to Pool1
110: Addition of Buffer Directories to Pool2
111: Reserved (Don't Use)
23:16 Reserved R/W 0 Reserved for future use. Writes ‘0’s.
15:0 Data Size/NOD R/W 0 Data Size/Number Of Buffer Directory:
The meaning of this field depends on the value written into the Command
field.
Command = 0xx: V R 4120A has to write the size of the transmitting data in
this field.
Command = 100, 101, 110: Indicates the number of Buffer Directories added
to a pool.
Command = 111: This field has no meaning.
6.2.16 U_CA (USB Command Extension Register)
This register is used for issuing Tx request or adding Rx Buffer Directories to Pool.
The V
R
4120A writes the start address of either the Tx or the Rx Buffer Directory into this register.
Bits Field R/W Default Description
31:0 Address R/W 0 The meaning of this field varies depending on the value written into the
Command field of the USB Command Register.
Command = 0xx: Start address of the transmit packet
Command = 100, 101, 110: Start address of the Buffer Directory to be added
to the receive pool
Command = 111: This register has no meaning.