Chapter 28 Fault Collection Unit (FCU)
MPC5602P Microcontroller Reference Manual, Rev. 4
780
Freescale Semiconductor
Figure 28-16. Dual rail coding example
28.3.2.2
Time switching protocol
FCU[0] is toggled between logic 0 and logic 1 with a defined frequency f = 1 kHz @ 64 MHz (f is
approximated, as shown by
) and duty cycle d = 50%.
Eqn. 28-1
Frequency can be varied by using the same prescaler as used for the dual-rail protocol (FOP field in
FCU_MCR). This frequency modulation protocol is violated when the FCU goes into Fault state.
During initialization phase, FCU[0] is set high. When a fault is detected, FCU[0] is set low.
Reset
Configuration phase
Normal behavior
Error occurred
FCU[0]
FCU[1]
During configuration phase
fake faults can be injected
so outputs may be different
Reset is asserted
EOUT freq = SYS_CLK
{4096 × [(FOP + 1) × 2]}
64 MHz
{4096 × [(7 + 1) × 2]} = 976.5 Hz