mfr4300 Freescale Semiconductor, Inc, mfr4300 Datasheet - Page 235

• Manufacturer Part Number: mfr4300
• Description: Flexray Communication Controllers
• Manufacturer: Freescale Semiconductor, Inc

7.3
The CRG contains the registers and associated bits for controlling and monitoring the FLEXRAY module.
7.4
The FLEXRAY block has two external pins, EXTAL and XTAL. The oscillator input pin, EXTAL, is
intended to be connected to either a crystal or an external clock source. The XTAL pin is an output signal
that provides crystal circuit feedback.
A buffered EXTAL signal, OSCCLK, becomes the internal reference clock. To improve noise immunity,
the oscillator is powered by the V
7.4.1
The clock monitor circuit is based on an internal resistor-capacitor (RC) time delay so that it can operate
without a clock. If no OSCCLK edges are detected within this RC time delay, the clock monitor indicates
a failure which asserts self clock mode or generates a system reset depending on the state of the SCME bit.
If the clock monitor is disabled or the presence of clocks is detected, no failure is indicated. The clock
monitor function is enabled/disabled by the CME control bit, described in
Generator
7.5
FLEXRAY contains a clock monitor, which can trigger a reset. The control bits and status bits for the clock
monitor are described in
Freescale Semiconductor
Memory Map and Register Definition
Functional Description
Resets
(CRG)”.
Clock Monitor (CM)
Chapter 6, “Clocks and Reset Generator
DDOSC
MFR4300 Data Sheet, Rev. 3
and V
SSOSC
power supply pins.
(CRG)”.
Chapter 6, “Clocks and Reset
Oscillator (FLEXRAY)
235