Electronic control device

• US 20080148107A1
• Filed: 12/14/2007
• Published: 06/19/2008
• Est. Priority Date: 12/19/2006
• Status: Active Grant

• Current Assignee: Fujitsu Ten Limited (DENSO Corporation)
• Original Assignee: Fujitsu Ten Limited (DENSO Corporation)
• Inventors: Komatsu, Kazuhiro, Matsui, Takashi, Yamaguchi, Kazuhi, Akaza, Masanori, Takaishi, Naoyuki, Fukuta, Megumi, Satomi, Tomoko, Takatomi, Shinichiro, Kasame, Tomohide
• Granted Patent: US 8,042,009 B2
• Time in Patent Office: Days
• US Class Current: 714/51
• CPC Class Codes: G06F 11/0739 in a data processing system embedded in automotive or aircraft systems
• CPC Class Codes: G06F 11/0757 by exceeding a time limit, i.e. time-out, e.g. watchdogs

Abstract

An electronic control device according to an embodiment of the present invention includes an arithmetic device such as a microcomputer having a watchdog timer circuit, and a runaway monitoring circuit which monitors the arithmetic device for an operational failure by receiving a pulse output from the arithmetic device, in which the watchdog timer circuit or the runaway monitoring circuit detects occurrence of a failure of the arithmetic device according to the state (high level or low level) of an indication signal (wakeup signal) which shows the operational state of the arithmetic device.

Claims

1. An electronic control device comprising:

an arithmetic device having a watchdog timer circuit; and

a runaway monitoring circuit which monitors the arithmetic device for an operational failure by receiving a pulse output from the arithmetic device;

wherein the watchdog timer circuit or the runaway monitoring circuit detects occurrence of a failure of the arithmetic device according to a state of an indication signal which shows an operational state of the arithmetic device.

2. The electronic control device according to claim 1, wherein the operational state of the arithmetic device is generated by the arithmetic device, and includes an activated state and a terminated state of the arithmetic device.

3. The electronic control device according to claim 1, further comprising:

a circuit which sets a signal line for outputting the indication signal from the arithmetic device at a specific electric potential showing the activated state of the arithmetic device after the power has been supplied;

wherein the runaway monitoring circuit monitors the arithmetic device for a runaway process when the signal line is at the specific electric potential.

4. The electronic control device according to claim 1, wherein the arithmetic device periodically outputs the pulse in the activated state and terminates output of the pulse in the terminated state.

5. The electronic control device according to claim 1, wherein the runaway monitoring circuit comprises a timer counter which starts a counting operation each time the timer counter receives the pulse, and a reset output circuit which outputs a reset signal to the arithmetic device when the timer counter is in a specific state.

6. The electronic control device according to claim 1, further comprising:

a signal processing section which performs an external signal exchange;

wherein the runaway monitoring circuit is provided in the signal processing section.