Renesas M16C Series User Manual

Universal Serial Bus
M30240 Group
Rev.1.00 Sep 24, 2003 Page 313 of 360
3.2.7.4 Suspend Signal Interrupt
An interrupt request occurs when the interrupt status flag of the USB Suspend Interrupt Status register
(SUSPIC) is “1.”
The USB Suspend Interrupt Status flag is set to “1” when the USB Suspend signal is received (when
there is no activity for at least 3ms on the D+/D- line).
3.2.7.5 USB SOF (Start of Frame) Interrupt
This interrupt is used to control isochronous transfers. Endpoint 1-4 can be used. When a SOF packet
is received from the host CPU, a USB SOF
interrupt request occurs. The interrupt request bit and its’
priority level select bit are set in the SOF Interrupt Control register (SOFIC).
3.2.8 USB Function Control Unit Initialization
The initialization of the USB function control unit for the M30240 Group is shown below. The initialization
routine is:
• Use the Frequency Synthesizer to generate 48MHz required for the f
USB
.
• Enable the USB Function Control unit.
• Initialize each endpoint.
Figure 3.26 shows a block diagram of the frequency synthesizer circuit; Figure 3.27 through Figure 3.30
show the procedures for setting the registers.
Figure 3.26: Frequency Synthesizer Circuit Block Diagram
FSP
Data Bus
FSM FSC FSD
03DE
16
03DD
16
03DC
16
03DF
16
Frequency
Multiplier
Frequency
Divider
8 Bit
LS
8 Bit
f(Xin)
f
VCO
f
SYN
f
USB
Prescaler
8 Bit
f
PIN
FSCCR
FSCCR0
03DB
16
EN
USBC5

Renesas M16C Series Specifications

General

Brand	Renesas
Model	M16C Series
Category	Computer Hardware
Language	English