c8051t623-g Silicon Laboratories, c8051t623-g Datasheet - Page 112

• Manufacturer Part Number: c8051t623-g
• Description: Full Speed Usb Eprom Mcu Family
• Manufacturer: Silicon Laboratories

18.3. USB Register Access
The USB0 controller registers listed in Table 18.2 are accessed through two SFRs: USB0 Address
(USB0ADR) and USB0 Data (USB0DAT). The USB0ADR register selects which USB register is targeted
by reads/writes of the USB0DAT register. See Figure 18.2.
Endpoint control/status registers are accessed by first writing the USB register INDEX with the target end-
point number. Once the target endpoint number is written to the INDEX register, the control/status registers
associated with the target endpoint may be accessed. See the “Indexed Registers” section of Table 18.2
for a list of endpoint control/status registers.
Important Note: The USB clock must be active when accessing USB registers.
USB0DAT
USB0ADR
SFRs
8051
Figure 18.2. USB0 Register Access Scheme
C8051T622/3 and C8051T326/7
Rev. 1.1
Registers
Registers
Common
Interrupt
Register
Access
Index
FIFO
USB Controller
Endpoint0 Control/
Endpoint1 Control/
Endpoint2 Control/
Status Registers
Status Registers
Status Registers
119