Determining a time base for a microcontroller
First Claim
1. A method for producing a time base for a microcontroller with a clock generator for a clock signal and an RC-element with a certain time constant, the method comprising:
- charging a capacitor of the RC-element to a starting voltage;
counting a number of pulses of the clock signal as the voltage on the capacitor of the RC-element falls to a predetermined percentage of the starting voltage or to a predetermined threshold voltage; and
thendetermining the time base as a function of the counted number of clock pulses.
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Abstract
The invention relates to a method for producing a time base for a microcontroller and a simple circuit arrangement therefor, which comprises an RC-element having a specific time constant, said element being connected to a connection of the microcontroller. According to said method, the capacitor of the RC element is charged to an initial voltage in a first step, then in a second step, the number of timed impulses is counted until the voltage on the capacitor falls below the initial voltage to a determined percentage of the initial voltage or a voltage threshold value, and then in a third step, the counted number of timed impulses is used as a time base.
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Citations
20 Claims
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1. A method for producing a time base for a microcontroller with a clock generator for a clock signal and an RC-element with a certain time constant, the method comprising:
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charging a capacitor of the RC-element to a starting voltage; counting a number of pulses of the clock signal as the voltage on the capacitor of the RC-element falls to a predetermined percentage of the starting voltage or to a predetermined threshold voltage; and
thendetermining the time base as a function of the counted number of clock pulses. - View Dependent Claims (2, 3, 4, 5)
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6. A time base determination circuit for a microcontroller with an internal clock generator that generates a clock signal, the circuit comprising:
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an external RC-element, including a capacitor and having a certain time constant; the RC-element electrically connected to the microcontroller wherein the capacitor is charged to a starting voltage, a number of pulses of the clock signal is counted as the voltage across the capacitor of the RC-element falls to a predetermined percentage of the starting voltage or to a predetermined threshold voltage, and the time base is determined as a function of the counted number of clock pulses. - View Dependent Claims (7, 8, 9)
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10. A time base determination circuit for a microcontroller with an internal clock generator that generates a clock signal and a non-volatile memory, the circuit comprising:
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an RC-element, including a capacitor and having a certain time constant; the RC-element electrically connected to the microcontroller wherein the capacitor is charged to a starting voltage, a number of pulses of the clock signal is counted as the voltage across the capacitor of the RC-element falls to a predetermined percentage of the starting voltage or to a predetermined threshold voltage, the counted number of clock pulses is stored in the non-volatile memory, and the time base is determined as a function of the counted number of clock pulses. - View Dependent Claims (11, 12, 13)
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14. A time base determination circuit for a microcontroller with an internal clock generator, the circuit comprising:
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an RC-element, including a capacitor and having a certain time constant; and an internal A/D converter for measuring a voltage applied to the RC-element; the RC-element electrically connected to the A/D converter and the microcontroller wherein the capacitor is charged to a starting voltage, a number of clock pulses generated by the clock generator is counted as the voltage across the capacitor of the RC-element falls to a predetermined percentage of the starting voltage or to a predetermined threshold voltage, and the time base is determined as a function of the number of clock pulses counted. - View Dependent Claims (15, 16, 17, 18)
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19. A time base determination circuit for a microcontroller with an internal clock generator, the circuit comprising:
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an RC-element, including a capacitor and having a certain time constant; and an internal A/D converter for measuring a voltage across the capacitor of the RC-element; the RC-dement electrically connected to the A/D converter and the microcontroller wherein the capacitor is charged to a starting voltage, a number of clock pulses generated by the clock generator is counted as the voltage across the capacitor of the RC-element falls to a predetermined threshold voltage, the number of clock pulses counted is stored in a non-volatile memory, the capacitor is recharged to the starting voltage, the clock generator of the microcontroller is switched off, and when the voltage across the capacitor fells to the predetermined threshold voltage, the clock generator is switched on. - View Dependent Claims (20)
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Specification