NEC Network Controller uPD98502 - Manual (Page 331)

CHAPTER 6 USB CONTROLLER
Preliminary User’s Manual S15543EJ1V0UM 331
6.4 Initialization
After USB Controller has been reset, the V
R
4120A must set several USB Controller registers. The initialization
sequence is listed below.
(1) A desired mode is set into the USB General Mode Register.
(2) The receive pools are placed in system memory, and the information they contain are set in the following
registers:
USB Rx Pool0 Information Register: (Address: 1000_1050H)
USB Rx Pool0 Address Register: (Address: 1000_1054H)
USB Rx Pool1 Information Register: (Address: 1000_1058H)
USB Rx Pool1 Address Register: (Address: 1000_105CH)
USB Rx Pool2 Information Register: (Address: 1000_1060H)
USB Rx Pool2 Address Register: (Address: 1000_1064H)
(3) The transmit/receive MailBoxes are placed in system memory, and the information they contain are set in the
following registers:
USB Tx MailBox Start Address Register (Address: 1000_1070H)
USB Tx MailBox Bottom Address Register (Address: 1000_1074H)
USB Rx MailBox Start Address Register (Address: 1000_1080H)
USB Rx MailBox Bottom Address Register (Address: 1000_1084H)
When Tx MailBox Start Address Register is set, the value in the register is copied to Tx MailBox Read
Address Register (Address: 1000_1078H) and Tx MailBox Write Address Register (Address: 1000_107CH).
In same way, when Rx MailBox Start Address Register is set, the value in the register is copied to Rx
MailBox Read Address Register (Address: 1000_1088H) and Rx MailBox Write Address Register (Address:
1000_108CH).
(4) A value is written into the MAXP field of the USB EP0 Control Register, the EP1-2 Control Register, the EP3-
4 Control Register, and the EP5-6 Control Register. Then, each EndPoint is enabled. The settings made up
to this point enable the start of data transmitting/receiving, as well as the ability to respond to Device
Configuration from the Host PC.
(5) Device Configuration is started through EndPoint0. Therefore, a response must be returned to EndPoint0. At
this stage, the USB Function Address is allocated. The V
R
4120A must set that value into the Function
Address field in USB General Mode Register (Address: 1000_1000H).
The initialization procedure is completed.
In addition to the above, it may be necessary to write a value into the USB Interrupt Mask Register (Address:
1000_1014H or 1000_101CH) and enable the interrupt.