Vehicle communications transceiver with loop-back diagnostic mode
First Claim
1. A communications transceiver operable for communicating data onto a communications bus and further operable in a loop-back mode, said transceiver comprising:
- a transmitter having waveshaping circuitry and an output for outputting data information onto the communications bus;
a receiver having an input coupled to the communications bus for receiving data information therefrom, said receiver processing the received data information and outputting the processed information; and
an internal loop-back path including switching means for decoupling said receiver from the communications bus and for routing an internal transmit signal to the receiver when said transceiver is in the loop-back mode so that diagnostic testing of the transmit signal may be performed without interference from the communications bus.
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Accused Products
Abstract
A vehicle communications network is provided which includes a ground translation circuit and interfacing transmitter circuits that achieve smooth current sourcing transitions. Included is a communications bus such as a J1850 having multiple-access for interfacing with a plurality of electronics, preferably within a vehicle. Each transceiver has a transmitter and receiver interfaced with the bus. The transceiver is coupled via a resistive element to the communications bus and sources current onto the bus when the transmitter output voltage exceeds the bus voltage. The added resistance advantageously reduces changes in current which may otherwise exist on the communications bus when current sourcing switches on and off.
20 Citations
11 Claims
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1. A communications transceiver operable for communicating data onto a communications bus and further operable in a loop-back mode, said transceiver comprising:
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a transmitter having waveshaping circuitry and an output for outputting data information onto the communications bus; a receiver having an input coupled to the communications bus for receiving data information therefrom, said receiver processing the received data information and outputting the processed information; and an internal loop-back path including switching means for decoupling said receiver from the communications bus and for routing an internal transmit signal to the receiver when said transceiver is in the loop-back mode so that diagnostic testing of the transmit signal may be performed without interference from the communications bus. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A vehicle communications transceiver integrated on a chip and operable for communicating data onto a vehicle communications bus and further operable in a loop-back mode, said transceiver comprising:
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a transmitter having an input for receiving encoded data communications information, waveshaping circuitry and an output circuit for outputting variable pulse width modulated data symbols onto the communications bus; a receiver having an input circuit coupled to the communications bus for receiving variable pulse width modulated data symbols therefrom, said receiver processing the received variable pulse width modulated data symbols and outputting processed data information to a microprocessor; and an internal loop-back path including at least one first switch for routing an internal transmit signal to the receiver when said transceiver is in the loop-back mode and at least one second switch for decoupling said receiver from the communications bus so that diagnostic testing may be performed without interference from the communications bus. - View Dependent Claims (9)
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10. A method of operating a communications transceiver for transmitting and receiving communications data between a node and a communications bus and operable to provide a loop-back mode, said method comprising the steps of:
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waveshaping communications data with a waveshaper circuit; transmitting the waveshaped communications data with a transmitter onto the communications bus; receiving communications data with a receiver from the communications bus; internally switching said transceiver between a normal transmit and receive operating mode and the loop-back mode; and internally routing the waveshaped communications data to the receiver when said transceiver is in the loop-back mode so that diagnostic testing of the waveshaped communications data may be performed without interference from the communications bus. - View Dependent Claims (11)
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Specification