Method and apparatus for evaluating and calibrating a signaling system
First Claim
1. A digital signaling system comprising:
- a transmit circuit, the transmit circuit comprising a transmit data input and a transmit data output, the transmit circuit producing a transmit data output signal at the transmit data output based on a transmit data input signal from the transmit data input when the transmit circuit is operating in a normal mode, the transmit circuit further comprising a transmit repeating pattern generator producing a repeating pattern signal, the transmit circuit producing the transmit data output signal at the transmit data output based on the repeating pattern signal when the transmit circuit is operating in a test mode; and
a receive circuit, the receive circuit operably coupled to the transmit circuit and receiving the transmit data output signal from the transmit circuit at a receive data input, the receive circuit comprising a receive data output, the receive circuit producing a receive data output signal at the receive data output based on the transmit data output signal when the receive circuit is operating in the normal mode, the receive circuit further comprising a receive repeating pattern generator producing the repeating pattern signal, the receive circuit producing a comparison signal based on a comparison dependent on the transmit data output signal and the repeating pattern signal when the receive circuit is operating in the test mode.
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Abstract
A method and apparatus for evaluating and calibrating a signaling system is described. Evaluation is accomplished using the same circuits actually involved in normal operation of the signaling system. Capability for in-situ testing of a signaling system is provided, and information may be obtained from the actual perspective of a receive circuit in the system. A pattern of test information is generated in a transmit circuit of the system and is transmitted to a receive circuit. A similar pattern of information is generated in the receive circuit and used as a reference. The receive circuit compares the patterns. Any differences between the patterns are observable. Preferably, the patterns are repeating patterns that allow many iterations of testing to be performed. In one embodiment, a linear feedback shift register (LFSR) is implemented to produce patterns. Information obtained from testing may be used to assess the effects of various system parameters, including but not limited to output current, crosstalk cancellation coefficients, and self-equalization coefficients, and system parameters may be adjusted to optimize system performance. An embodiment of the invention may be practiced with various types of signaling systems, including those with single-ended signals and those with differential signals. An embodiment of the invention may be applied to systems communicating a single bit of information on a single conductor at a given time and to systems communicating multiple bits of information on a single conductor simultaneously.
207 Citations
23 Claims
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1. A digital signaling system comprising:
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a transmit circuit, the transmit circuit comprising a transmit data input and a transmit data output, the transmit circuit producing a transmit data output signal at the transmit data output based on a transmit data input signal from the transmit data input when the transmit circuit is operating in a normal mode, the transmit circuit further comprising a transmit repeating pattern generator producing a repeating pattern signal, the transmit circuit producing the transmit data output signal at the transmit data output based on the repeating pattern signal when the transmit circuit is operating in a test mode; and
a receive circuit, the receive circuit operably coupled to the transmit circuit and receiving the transmit data output signal from the transmit circuit at a receive data input, the receive circuit comprising a receive data output, the receive circuit producing a receive data output signal at the receive data output based on the transmit data output signal when the receive circuit is operating in the normal mode, the receive circuit further comprising a receive repeating pattern generator producing the repeating pattern signal, the receive circuit producing a comparison signal based on a comparison dependent on the transmit data output signal and the repeating pattern signal when the receive circuit is operating in the test mode. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A method for evaluating a digital signaling system comprising the steps of:
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generating a transmit repeating pattern in a transmit circuit;
transmitting the transmit repeating pattern to a receive circuit;
generating a receive repeating pattern in the receive circuit; and
comparing the transmit repeating pattern to the receive repeating pattern to obtain a comparison. - View Dependent Claims (10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23)
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Specification