Microcode with Embedded Timing Constraints

: Watchdogs are a well-known and widespread means to increase the safety of microprocessors. The programmer or the compiler must insert instructions to reset the watchdog. If the programmer or compiler chose the wrong timing values or forgot to insert instructions to reset the timer, the processor will never be able to fulfill its task, because it will be set back to an initial (known) state each time it encounters a timing violation. We eliminate the need to insert special instructions and dedicated external watchdog hardware. Our strategy is able to detect transient control-flow faults in state automata and faulty BUSY-signals of execution units in microcode-based microprocessors. The innovation is to introduce fixed timings for each microcode so explicit instruction sequences to reset the watchdog timer are not necessary any more. Each execution unit receives a timing value from the microcode ROM. A unit-specific cycle counter is set to the timing from the microcode (

• Type: Conference
• Year: 2006
• Where: ARCS
• Authors: Bernhard Fechner
• Keywords: ARCS 2006, Maximal Timing, Microcode, Software Engineering, Timing Value