Universal Serial Bus
M30240 Group
Rev.1.00 Sep 24, 2003 Page 47 of 360
1.2.18.4.2 USB Control Register
The USB Control Register, shown in Figure 1.31, is used to control the USB FCU. This register is not reset by
a USB reset signaling. After the USB is enabled (USBC7 set to “1”), a minimum delay of 250ns (three 12 MHz
clock periods) is needed before performing any other USB register read/write operations.
Figure 1.31: USB Control Register
1.2.18.4.3 USB Function Address Register
The USB Function Address Register, shown in Figure 1.32, maintains the 7-bit USB address assigned by the
host. The USB FCU uses this register value to decode USB token packet addresses. At reset, when the device
is not yet configured, the value is 00
16
. For the procedures on how to update this register, refer to Application
Notes USB Consecutive Set Address.
Figure 1.32: USB Function Address Register
USB Control Register
Symbol Address When reset
USBC 000C16 0016
Bit name
Bit symbol
b7 b6 b5 b4 b3 b2 b1 b0
Function
W
R
Must always be set to "0"
Reserved
USBC3
USBC4
USBC5
USBC6
USBC7
Tranceiver voltage converter
High/Low current mode selection
USB tranceiver voltage converter
enable bit
USB clock enable bit
USB SOF port select bit
USB enable bit
0: High current mode (Note 1)
1: Low current mode (Note 2)
0: Disabled
1: Enabled
0: Disabled
1: Enabled
0: Disabled (Note 3)
1: Enabled
0: Disabled (Note 4)
1: Enabled
Note 1: For USB normal operation
Note 2: For USB suspend operation
Note 3: P8
6
is used as GPIO pin
Note 4: All USB internal registers are held at their default values.
0
0
0
USB Function Address Register
Symbol Address When reset
USBA 0300
16
00
16
Bit nameBit symbol
b7 b6 b5 b4 b3 b2 b1 b0
FUNAD0-6
Function WR
Reserved Must always be set to "0"
7-bit programmable
Function Address
Function Address
0
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