MC908JB16DWE Datasheet, PDF (173/332 Pages) Freescale Semiconductor, Inc – Microcontrollers

Universal Serial Bus Module (USB)
V_OH (min.)
LAST BIT OF
PACKET
EOP
STROBE
BUS DRIVEN TO
IDLE STATE
BUS FLOATS
BUS IDLE
V_SE (max)
V_SE (min.)
V_OL (min.)
V_SS
Figure 11-7. EOP Transaction Voltage Levels
The width of the SE0 in the EOP is about two bit times. The EOP width
is measured with the same capacitive load used for maximum rise and
fall times and is measured at the same level as the differential signal
crossover points of the data lines.
t_Period
DIFFERENTIAL
DATA LINES
DATA
CROSSOVER
LEVEL
EOP
WIDTH
Figure 11-8. EOP Width Timing
11.5.2 Reset Signaling
The USB module will detect a reset signaled on the bus by the presence
of an extended SE0 at the USB data pins of a device. The MCU seeing
a single-ended 0 on its USB data inputs for more than 8µs treats that
signal as a reset.
A USB sourced reset will hold the MCU in reset for the duration of the
reset on the USB bus. The USB bit in the reset status register (SRSR)
will be set after the internal reset is removed. Refer to 8.8.2 SIM Reset
Status Register (SRSR) for more detail. The MCU’s reset recovery
sequence is detailed in Section 8. System Integration Module (SIM).
MC68HC908JB16 — Rev. 1.1
Freescale Semiconductor
Universal Serial Bus Module (USB)
Technical Data
173