Reducing input signal levels to a microprocessor

• US 5,956,247 A
• Filed: 01/29/1997
• Issued: 09/21/1999
• Est. Priority Date: 10/26/1992
• Status: Expired due to Term

• Current Assignee: Lear Corporation Eeds & Interiors (Rtx Corporation)
• Original Assignee: Lear Automotive Dearborn, Incorporated (Lear Corporation)
• Inventors: Kolomyski, Darrell J., Settles, Steven R.
• Primary Examiner(s): Gordon, Paul P.
• Assistant Examiner(s): Garland, Steven R.
• Application Number:
  US08/792,690
• Time in Patent Office: 965 Days
• Field of Search: 364/140, 364/141, 364/142, 364/140.01-140.1, 307/10.1, 307/11, 307/38, 370/85.1, 370/85.3, 370/476, 340/825.62, 340/825.63, 340/825.61
• US Class Current: 700/11
• CPC Class Codes: G05B 19/0423 Input/output
• CPC Class Codes: G05B 2219/21165 Zenerdiodes for protection of output of transmitter, input of receiver
• CPC Class Codes: G05B 2219/25134 All interfaces load their data in shift register, then serial read out
• CPC Class Codes: G05B 2219/25435 Multiplex for analog signals
• CPC Class Codes: G05B 2219/2637 Vehicle, car, auto, wheelchair

Abstract

A plurality of switches are connected to a lesser plurality of shift registers which are controlled by the microcontroller to provide serial binary signals over a single data line with a voltage level clamp by a zener diode in response to clock pulses. A second plurality of switches and rheostats are supplied to a lessor plurality of multiplexers. One of the input channels to each of the multiplexers is selected in response to a channel select signal provided by the microcontroller. The registers and multiplexers produce output signals that are clamped to a lower microcontroller operating level. Signals from the microcontroller are skipped as to control the registers and multiplexers. The operation of the switches and rheostats is used by the microcontroller to control the power devices such as lights, windows, turn signals and air conditioning.

Claims

1. A automotive system for controlling a plurality of devices, each device of said plurality having an activating status, said system receiving a number of control signals, the activating status of each device of said plurality corresponding with each control signal of said number, said system comprising:

first means, responsive to a clock signal, for producing a serial signal having a first voltage, said serial signal having a multiplicity of data bits, each data bit of said multiplicity corresponding with a control signal of said number;

means for clamping said serial signal to a second voltage, said second voltage being below said first voltage;

means for producing the clock signal according to a routine, said routine correlating each data bit of said multiplicity with a device of said plurality; and

a microcontroller for intermittently polling the activating status of each device of said plurality, and for controlling the activating status of each device of said plurality in response to receiving said clamped serial signal.

2. A system according to claim 1, wherein the first means comprises a shift register.

3. The automotive system of claim 1 wherein said means for producing the clock signal comprises said microcontroller running said routine.

4. A automotive system for controlling a plurality of devices, each device of said plurality having an operating status, said system receiving a number of control signals, the operating status of each device of said plurality corresponding with each control signal of said number, said system comprising:

first means for receiving each control signal of said number, and for selectively transmitting a control signal of said number in response to a select signal, said selectively transmitted control signal corresponding with a selected device and having a first voltage;

means for clamping said selectively transmitted control signal to a second voltage, said second voltage being below said first voltage;

means for producing the select signal according to a routine, said routine correlating said select signal to each control signal of said number and a device of the plurality; and

a microcontroller for intermittently polling the activating status of each device of said plurality, and for controlling the operating status of said selected device in response to receiving said clamped selectively transmitted control signal.

5. A system according to claim 4, wherein the first means comprises an analog multiplexer.

6. An automotive system comprising:

a plurality of vehicle devices, each device of said plurality having an activating status;

a number of switches, each switch of said number for generating a control signal corresponding with a vehicle device of said plurality such that a number of control signals are generated;

a shift register for receiving each control signal of said number and for producing a serial signal of data bits at a first voltage in synchronism with a clock signal, each data bit of said data bits corresponding with a control signal of said number;

a zener diode for clamping the serial signal to a second voltage, said second voltage being less than said first voltage; and

a microcontroller for intermittently polling the activating status of each device of said plurality, for producing said clock signal according to a routine, said routine correlating each data bit of said serial signal with a device of said plurality, and for controlling the activating status of each device of said plurality in response to receiving said clamped serial signal.

7. An automotive system comprising:

a plurality of vehicle devices, each device of said plurality having an operating status;

a number of switches, each switch of said number for generating a control signal corresponding with a vehicle device of said plurality such that a number of control signals are generated;

an analog multiplexer for receiving each control signal of said number and for selectively transmitting a control signal of said number in response to a select signal, said selectively transmitted control signal corresponding with a selected vehicle device and having a first voltage;

a zener diode for clamping the transmitted control signal from the multiplexer to a second voltage, said second voltage being less than said first voltage; and

a microcontroller for intermittently polling the activating status of each device of said plurality, for producing said select signal according to a routine, said routine correlating said select signal to a control signal of said number and a device of the plurality, and for controlling the operating status of said selected vehicle device in response to receiving said clamped selectively transmitted control signal.

8. A method of applying power to a number of vehicle devices using a plurality of switches having an operating status, each switch of said plurality for controlling a device of said number, said method comprising the steps of:

providing a device control signal indicating the operating status of a switch of said plurality in response to a select signal provided from a microcontroller and being at a first voltage;

clamping said device control signal to a second voltage, said second voltage being below said first voltage;

receiving the device control signal on an input on a microcontroller;

providing the select signal according to a routine stored in the microcontroller, the routine correlating the select signal to the device control signal and a vehicle device of said number;

powering a first device of said number by providing a drive signal to the first device in response to the device control signal being correlated to the first device according to the stored routine.

9. A method of applying power to a number of vehicle devices using a plurality of switches having an activating status, each switch of said plurality for controlling a device of said number, said method comprising the steps of:

generating a serial signal comprising a multiplicity of data bits in response to a clock signal, each data bit of said multiplicity indicating the activating status of a switch of said plurality;

clamping said serial signal to a second voltage, said second voltage being below said first voltage;

receiving the serial signal on an input terminal of a microcontroller;

providing said clock signal according to a routine stored in the microcontroller that correlates each bit of said multiplicity with a device of said number;

controlling the activating status of each device of said plurality in response to said microcontroller receiving each bit of said multiplicity of said clamped serial signal.

10. A automotive system for controlling a number of vehicle devices, said system having a plurality of enabling signals as inputs, each enabling signal of said plurality corresponding with a vehicle device of the number of vehicle devices, said system comprising:

a shift register for serializing said plurality of enabling signals such that a serialized enabling signal is generated in response to a clock signal, said clock signal being generated according to a routine, said routine correlating said serialized enabling signal with a device of said number;

a voltage clamp for clamping said serialized enabling signal such that a clamped serialized enabling signal is generated; and

a microcontroller for intermittently polling the activating status of each device of said plurality, and for controlling each vehicle device of the number in response to said clamped serialized enabling signal.

11. The system of claim 10, wherein said microcontroller comprises a clock system for generating said clock signal.

12. The system of claim 10, wherein each enabling signal of said plurality comprises a first voltage level, and said voltage clamp comprises a zener diode for clamping said serialized enabling signal to a second voltage level below said first voltage level.

13. The system of claim 10, further comprising a plurality of switches, each switch of said plurality for generating one enabling signal of said plurality.

14. The system of claim 13, wherein each of said plurality of switches comprises a first and a second resistor for forming a voltage divider circuit.

15. A automotive system for controlling a number of vehicle devices, said system having a plurality of enabling signals as inputs, each enabling signal of said plurality corresponding with a vehicle device of the number of vehicle devices, said system comprising:

a multiplexer for receiving each enabling signal of said plurality and for selectively transmitting an enabling signal of said plurality in response to a select signal, said select signal generated according to a routine, said routine correlating each enabling signal of said plurality to a device of the number, said selectively transmitted enabling signal corresponding with a selected vehicle device and having a first voltage;

a voltage clamp for clamping said selectively transmitted enabling signal such that a clamped selectively transmitted enabling signal is generated; and

a microcontroller for intermittently polling the activating status of each device of said plurality, and for controlling each vehicle device of said number in response to said clamped selectively transmitted enabling signal.

16. The system of claim 15, wherein said voltage clamp comprises a zener diode for clamping each enabling signal generated by each switch of said plurality to a second voltage level below said first voltage level.

17. The system of claim 16, wherein said multiplexer comprises a first and a second multiplexer and a selection transistor for selecting between said multiplexers in response to said output signal.