Microcontroller, control device and determination method

Patent metadata

Field	Value
Publication number	US-9323595-B2
Application number	US-201213555123-A
Country	US
Kind code	B2
Filing date	Jul 21, 2012
Priority date	Jul 21, 2011
Publication date	Apr 26, 2016
Grant date	Apr 26, 2016

Abstract

A microcontroller includes a central processing unit, a PWM signal generation unit which generates a PWM signal according to a generation condition of a PWM signal set by the central processing unit, and a diagnostic unit which inputs the generated PWM signal therein and detects a pulse period and a pulse width, based on the input signal and which determines whether the detected pulse period and pulse width respectively coincide with a pulse period and a pulse width corresponding to the generation condition.

First claim

What is claimed is:

1. A microcontroller comprising:
a central processing unit;
a PWM signal generation unit which generates a PWM signal according to a stored generation condition set by the central processing unit, the stored generation condition being stored in a register; and
a diagnostic unit which detects a pulse period and a pulse width of the PWM signal generated by the PWM signal generation unit and compares the detected pulse period and pulse width with a pulse period and pulse width corresponding to the stored generation condition to thereby perform a diagnosis of the PWM signal generation unit,
wherein when the stored generation condition under which the pulse width of the PWM signal becomes zero is set to the PWM signal generation unit, the diagnostic unit corrects an input PWM signal to be a high level only for a first period shorter than the pulse period for the set stored generation condition and detects a pulse period and a pulse width of the corrected PWM signal to thereby perform the comparison.

2. A microcontroller according to claim 1 , wherein when the stored generation condition under which the pulse width and the pulse period of the PWM signal coincide with each other is set to the PWM signal generation unit, the diagnostic unit corrects the input PWM signal to be a low level for only a second period shorter than the pulse period for the set stored generation condition and detects a pulse period and a pulse width of the corrected PWM signal to thereby perform the comparison.

3. A microcontroller according to claim 2 ,
wherein the diagnostic unit comprises:
a pulse correction unit which corrects the input PWM signal and outputs a corrected PWM signal according to the stored generation condition set to the PWM signal generation unit;
a detection unit which detects rising and falling edges of the signal outputted from the pulse correction unit; and
a comparison unit which calculates a pulse period and pulse width of the signal outputted from the pulse correction unit, based on the detected edges and compares the calculated pulse period and pulse width with the pulse period and pulse width corresponding to the stored generation condition,
wherein when the stored generation condition under which the pulse width of the PWM signal becomes zero is set to the PWM signal generation unit, the pulse correction unit generates a first signal brought to a high level only for the first period with a timing at which a time corresponding to a pulse period has elapsed from a rising edge of the immediately preceding PWM signal and takes a logical ORing of the first signal and the input PWM signal to thereby generate the corrected PWM signal, and
wherein when the stored generation condition under which the pulse width of the PWM signal becomes zero is set to the PWM signal generation unit, the comparison unit determines that the PWM signal corresponding to the stored generation condition has been generated if the calculated pulse period and the pulse period corresponding to the stored generation condition coincide with each other, and the calculated pulse width and the pulse width corresponding to the first period coincide with each other, and determines that the PWM signal corresponding to the stored generation condition has not been generated if the calculated pulse period and the pulse period corresponding to the stored generation condition do not coincide with each other or the calculated pulse width and the pulse width corresponding to the first period do not coincide with each other.

4. A microcontroller according to claim 3 ,
wherein when the stored generation condition under which the pulse width and the pulse period of the PWM signal coincide with each other, is set to the PWM signal generation unit, the pulse correction unit generates a second signal brought to a high level only for the second period with a timing at which a predetermined period has elapsed from the time when the input PWM signal has risen, and takes a logical ANDing of an inverted signal of the second signal and the input PWM signal to thereby generate the corrected PWM signal, and
wherein when the stored generation condition under which the pulse width and the pulse period of the PWM signal coincide with each other is set to the PWM signal generation unit, the comparison unit determines that a PWM signal corresponding to the stored generation condition has been generated if the calculated pulse period and the pulse period corresponding to the stored generation condition coincide with each other and the calculated pulse width and a pulse width obtained by making the pulse width corresponding to the stored generation condition shortened by the second period coincide with each other, and the comparison unit determines that the PWM signal corresponding to the stored generation condition has not been generated if the calculated pulse period and the pulse period corresponding to the stored generation condition do not coincide with each other or the calculated pulse width and the pulse width shortened by the second period do not coincide with each other.

5. A microcontroller according to claim 2 ,
wherein the PWM signal generation unit comprises a first register for storing therein the stored generation condition including a pulse period and pulse width,
wherein the diagnostic unit further comprises a second register for storing therein information including the stored generation condition stored in the first register, and
wherein the diagnostic unit performs the determination, based on the stored generation condition stored in the second register.

6. A microcontroller according to claim 5 , wherein the diagnostic unit monitors writing of the stored generation condition into the first register by the central processing unit, acquires the stored generation condition to be written by the central processing unit and stores the same in the second register.

7. A microcontroller according to claim 6 ,
wherein the central processing unit, the PWM signal generation unit and the diagnostic unit are coupled to one another via an internal bus,
wherein the central processing unit outputs an address value indicative of the first register and data related to the stored generation condition onto the internal bus when the stored generation condition is written into the first register, and
wherein the diagnostic unit monitors address values outputted onto the internal bus, and when an outputted address value is found to be the address value indicative of the first register, the diagnostic unit acquires the data related to the stored generation condition outputted onto the internal bus and holds the data in the second register.

8. A microcontroller according to claim 2 , further comprising:
a first terminal for outputting the PWM signal generated by the PWM signal generation unit to the outside, and
a second terminal for inputting a signal from outside, and
wherein the diagnostic unit is capable of selecting the PWM signal outputted to the first terminal and the PWM signal inputted via the second terminal as PWM signals for the comparison.

9. A microcontroller according to claim 2 , wherein the PWM signal generation unit and the diagnostic unit are configured within a common circuit module.

10. A microcontroller according to claim 2 , wherein the PWM signal generation unit and the diagnostic unit are configured as circuit modules separated from each other.

11. A microcontroller according to claim 2 , further comprising:
a first bus operated with a first bus clock and to which the central processing unit is coupled,
a second bus operated with a second bus clock different from the first bus clock and to which the PWM signal

Assignees

• Yamada Hiromichi
• Sakata Teruaki
• Kanekawa Nobuyasu
• Ishiguro Yuichi
• Yasumasu Takashi
• Fukuda Kazuyoshi
• Hagiwara Kesami
• Renesas Electronics Corp

Inventors

• Yamada Hiromichi
• Sakata Teruaki
• Kanekawa Nobuyasu
• Ishiguro Yuichi
• Yasumasu Takashi
• Fukuda Kazuyoshi
• Hagiwara Kesami

Classifications

• G06F11/0739

  in a data processing system embedded in automotive or aircraft systems · CPC title

• G06F11/0754 Primary

  by exceeding limits · CPC title

• G06F13/00

  Interconnection of, or transfer of information or other signals between, memories, input/output devices or central processing units (interface circuits for specific input/output devices G06F3/00 {; multiprogram control therefor  G06F9/46}; multiprocessor systems  G06F15/16 ) · CPC title

• Y02D10/00

  Energy efficient computing, e.g. low power processors, power management or thermal management · CPC title