NEC switch - Manual (Page 100)

CHAPTER 8 USB FUNCTION
User’s Manual U12978EJ3V0UD
100
Figure 8-3. Block Diagram of USB Timer
Internal bus
UWDERR
INTUSBTM
f
X
USBCLK
RESUME RX Note Clear circuit
Clock controller
Shift register
In high-
speed mode In low-
speed mode
DATATX SETORX
JUDGE TX Note
JUDGE TOKEN Note
TX MASTER EN Note
SETRX Note
OUT RX Note
USB timer start reservation
control register (USBTCL)
Note As these signals are used internally, confirmation by software is not possible.
Remark f X : System clock oscillation frequency
UWDERR: Bit 7 of packet receive status register (RXSTAT)