m5m51016btp Renesas Electronics Corporation., m5m51016btp Datasheet - Page 148

• Manufacturer Part Number: m5m51016btp
• Description: Renesas 16-bit Single-chip Microcomputer M16c Family / M16c/20 Series
• Manufacturer: Renesas Electronics Corporation.

M30245 Group
Rev.2.00 Oct 16, 2006
REJ09B0340-0200
Figure 2.8.9. USB control register
2.8.2 USB function control
The USB function control unit needs to be enabled for using the USB function. The initialization procedure
of the USB function control unit is explained below:
USB Control register
(1) Related Registers
b7
This register is used to control each operation of the USB function control unit. When using the USB
function, be sure to set USB clock enable bit to “1” before USB enable bit is set to “1”. This register is
not affected by the USB reset signal. After the USB is enabled (USBC7 =“1”), a minimum 187.5 ns of
delay (three cycles of BCLK) is required before performing any other USB register read/write opera-
tions.
•USB clock enable bit
•USB SOF port select bit
•USB enable bit
The configuration of USB control register is shown in Figure 2.8.9.
USB control register
This bit is used to enable/disable the USB clock (fusb). This clock is supplied from frequency synthe-
sizer and is required for the USB operation. Set this bit to “1” when enabling the USB clock.
This bit is used to enable/disable a SOF signal output on the P9
USB SOF signal. In this case, set the port P9
always output for about 166ns (2 cycles of the 12MHz USB clock) at start of the frame packet.
This bit is used to enable/disable the USB block. When this bit is set to “1”, USB function is enabled.
After setting “1” to this bit, wait for at least 250ns and, then, read or write the other USB related
register.
b6
b5
________
b4
0
b3
0
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b2
0
b1
0
b0
0
Note 1: P9
Note 2: All USB internal registers are held at their default values.
Bit Symbol
Reserved
USBC5
USBC6
USBC7
Symbol
USBC
2
is used as GPI/O pin.
USB clock enable bit
USB SOF port select bit
USB enable bit
2
to output mode. When this bit is set to “1”, low pulse is
Bit Name
Address
000C
16
2
Must always be set to “0”
0 : Disable
1 : Enable
0 : Disable (Note 1)
1 : Enable
0 : Disable (Note 2)
1 : Enable
pin. Set this bit to “1” when using the
Function
When reset
00
2. USB function
16
O O
O O
R W
O O
O O