US 11,971,447 B2
Automatic fault injection in a clock monitor unit
Praveen Durga, Austin, TX (US); Parul Bansal, Delhi (IN); and Ritu Prasad, Uttam Nagar (IN)
Assigned to NXP USA, Inc., Austin, TX (US)
Filed by NXP USA, Inc., Austin, TX (US)
Filed on Sep. 18, 2020, as Appl. No. 17/024,814.
Prior Publication US 2022/0091186 A1, Mar. 24, 2022
Int. Cl. G01R 31/317 (2006.01); G06F 1/10 (2006.01); G01R 23/15 (2006.01); G06F 11/07 (2006.01)
CPC G01R 31/31727 (2013.01) [G06F 1/10 (2013.01); G01R 23/15 (2013.01); G06F 11/0751 (2013.01)] 10 Claims
OG exemplary drawing
 
1. A method for operating a clock monitor unit configured to monitor a clock signal, the method comprising:
performing, by logic circuitry of the clock monitor unit in a functional operating mode, a first comparison of an operating frequency of the clock signal to a specified frequency range during a first measurement window;
selectively asserting or deasserting, by the logic circuitry in the functional operating mode, one or more event signals based on the first comparison,
modifying, by the logic circuity in a fault injection operating mode, thresholds that define the specified frequency range to cause a fault during a second measurement window;
performing, by the logic circuitry in the fault injection operating mode, a second comparison of the operating frequency of the clock signal to the modified thresholds during the second measurement window;
selectively asserting or deasserting, by the logic circuitry in the fault injection operating mode, the one or more event signals based on the second comparison; and
generating, by the logic circuitry in the fault injection operating mode, at least one signal indicating successful or failed detection of the fault by the clock monitor unit in the second measurement window based on the one or more event signals.