Process for decoding a digital signal and a bus system and a peripheral unit therefor

• US 6,185,252 B1
• Filed: 10/01/1997
• Issued: 02/06/2001
• Est. Priority Date: 10/21/1996
• Status: Expired due to Fees

• Current Assignee: Robert Bosch GmbH
• Original Assignee: Robert Bosch GmbH
• Inventors: Bauer, Joachim
• Primary Examiner(s): Chin, Stephen
• Assistant Examiner(s): GHAYOUR, MOHAMMAD H
• Application Number:
  US08/941,846
• Time in Patent Office: 1,224 Days
• Field of Search: 375/238, 327/26, 327/172, 329/312, 701/29
• US Class Current: 375/238
• CPC Class Codes: B60R 2021/01075 between the airbag control unit and pyrotechnic fuses or equivalent actuators
• CPC Class Codes: B60R 2021/01115 specific data frames
• CPC Class Codes: H04L 25/4902 Pulse width modulation; Pulse position modulation

Abstract

In a method for decoding digital PWM signal and a bus system, a peripheral unit, and a device therefor, the digital signal is decoded by integrating the pulse width of each bit and then comparing the integration result with a reference signal. The bus system includes dual wires, a device, and at least one peripheral unit. In an embodiment of the present invention, the bus system issued as an air bag system where diagnostic and deployment commands are sent via the bus wires to one or more peripheral units which control individual air bags.

Claims

1. A method for decoding a digital signal with pulse-width modulated bits, wherein a bit can assume one of a high signal level and a low signal level, and wherein a total pulse width of each bit is unknown, the method comprising the steps of:

integrating a signal level of each bit of the digital signal over the total pulse width of each bit;

transmitting the integrated signal level to a comparator;

generating a second signal; and

adding a level of the second signal to the signal level of each bit of the digital signal prior to integrating the signal level of each bit;

wherein a value of the second signal provides that a polarity of the integrated signal level is determined as a function of a value of the integrated bit, and wherein the comparator is a polarity discriminator.

2. A method for decoding a digital signal with pulse-width modulated bits, wherein a bit can assume one of a high signal level and a low signal level, and wherein a total pulse width of each bit is unknown, the method comprising the steps of:

integrating a signal level of each bit of the digital signal over the total pulse width of each bit;

transmitting the integrated signal level to a comparator; and

adding a constant value to the integrated signal level to the integrated signal level prior to supplying the result to the comparator;

wherein the constant value provides that a polarity of the integrated signal level is determined as a function of a value of the integrated bit, and wherein the comparator is a polarity discriminator.

3. A method for decoding a digital signal with pulse-width modulated bits, wherein a bit can assume one of a high signal level and a low signal level, and wherein a total pulse width of each bit is unknown, the method comprising:

forming an integration signal by evaluating a signal level of the digital signal over the total pulse width of each bit to a start of a following bit, the forming step including integrating the signal level of the digital signal over the total pulse width of each bit to the start of the following bit, and forming the integration signal as a function of the integrating step;

comparing the integration signal to a comparison signal;

providing the integration signal to a comparator;

generating a second signal; and

adding a level of the second signal to the signal level of each bit of the digital signal prior to integrating the signal level of the digital signal over the total pulse width of each bit;

wherein a value of the second signal provides that a polarity of the integrated signal has a different polarity depending on a value of each bit, and wherein the comparator is a polarity discriminator.

4. A method for decoding a digital signal with pulse-width modulated bits, wherein a bit can assume one of a high signal level and a low signal level, and wherein a total pulse width of each bit is unknown, the method comprising:

forming an integration signal by evaluating a signal level of the digital signal over the total pulse width of each bit to a start of a following bit, the forming step including integrating the signal level of the digital signal over the total pulse width of each bit to the start of the following bit, and forming the integration signal as a function of the integrating step;

comparing the integration signal to a comparison signal;

providing the integration signal to a comparator;

adding a constant value to the integrated signal prior to supplying the integration signal to the comparator;

wherein the constant value provides that a polarity of the integrated signal has a different polarity depending on a value of each bit, and wherein the comparator is a polarity discriminator.

5. A method for decoding a digital signal with pulse-width modulated bits, wherein a bit can assume one of a high signal level and a low signal level, and wherein a total pulse width of each bit is unknown, the method comprising:

forming an integration signal by evaluating a signal level of the digital signal over the total pulse width of each bit to a start of a following bit;

comparing the integration signal to a comparison signal; and

providing the integration signal to a comparator;

wherein the forming step includes forming a periodic signal having a frequency that is proportional to the signal level of the digital signal, counting a number of periods of the periodic signal, the count being started anew for each bit, and forming the integration signal as a function of the counting step.

6. The method according to claim 5, further comprising:

adding an additional signal to the digital signal, wherein a polarity of the digital signal is preserved during the total pulse width of each bit of the digital signal.

7. The method according to claim 5 further comprising:

adding a predefined number to the count result prior to transmitting the count result to the comparator.