AN4124

FCCU settings

Doc ID 023294 Rev 2

17/32

Example procedure

●

After the reset the FCCU automatically enters NORMAL state.

●

Configure FCCU in CONFIG with Dual-rail Encoding Protocol.

–

Write the key to the FCCU_CTRLK register [OP1].

–

Write the FCCU_CTRL register (operation OP1).

●

Emulate all (fake) SW/HW faults.

–

FCCU_CFG_TO=0x7 (Set Timer Out)

–

FCCU_CFG: (Configuration Register)

–

SM=1 (EOUT protocol (dual-rail, time-switching) fast switching mode)

–

PS=1 (fcc_eout[1] active low, fcc_eout[0] active low)

–

FOM=000 (Fault Output Mode selection= Dual-Rail (default state) [fccu_eout[1:0]=

outputs])

–

FOP=0 (Fault Output Prescaler= Input clock frequency (ipg_clk_safe clock) is

divided by 2 x 1024)

–

FCCU_NCFS_CFG0 = 0 (No reset reaction)

–

FCCU_NCFE0 = 0xFFFFFFFF; (Enable FCCU to move to ALARM or FAULT

State)

–

FCCU_NCF_TOE0 = 0xFFFFFFFF; (FCCU moves into the ALARM state if the

respective fault is enabled (NCFEx is set))

–

FCCU_NCF_TO = 0xFFFFFFFF; (Non-critical fault time-out)

●

Enter NORMAL state.

–

Write the key to the FCCU_CTRLK register [OP2].

–

Write the FCCU_CTRL register (operation OP2).

●

Set fault by FCCU_NCFF registers (NCF N. 12).

●

ISR assertion: FAULT_ISR managing (ISR N. 250)

●

Read and verify FCCU_NCFS0..3 by means of procedure.

●

Clear HW/SW faults from FCCU_NCFS0..3 by means of procedure.

Code

After the core initialization in main function the code is:

if((tc1_INIT()) == PASS){

/* ----------------- Fake NCF Fault --------------------- */

FCCU.NCFF.R = 12;

/* N. 12 NCF Fault injection */

Delay(10000);

/* Delay */

}else{

/* tc1_INIT - FAILURE */

}

Description

At the beginning the micro is in DRUN mode. The FCCU is configured in the tc1_INIT. Next

the NCF 12 is set. When the injection fault is asserted (FCCU.NCFF.R = 12), the system

asserts FAULT ISR. In FAULT ISR the fault is cleared and the system enters RUN mode.