Cable detection in a pin constrained connector
View Patent ↗A method of detecting a cable connected to a first device includes generating a second signal within the first device, and outputting the second signal onto an input-only pin of a cable connector on the first device, wherein the input-only pin is assigned to receive a first signal from a driver on a second device when a cable is connected from the second device to the cable connector, and wherein the second signal has a frequency that is at least four times greater than the frequency of the first signal. The method further comprises determining that a cable is not connected to the cable connector in response to detecting the second signal on a wire coupled to the input-only pin, and determining that the cable is connected to the cable connector in response to detecting a signal other than the second signal.
1. A method of detecting a cable connected to a first device, comprising:
generating a second signal within the first device;
outputting the second signal onto an input-only pin of a cable connector on the first device, wherein the input-only pin is assigned to receive a first signal from a driver on a second device when a cable is connected from the second device to the cable connector, and wherein the second signal has a frequency that is at least four times greater than the frequency of the first signal;
determining that a cable is not connected to the cable connector in response to detecting the second signal on a wire connected to the input-only pin; and
determining that the cable is connected to the cable connector in response to detecting a signal other than the second signal.
2. The method of claim 1 , further comprising:
generating a negative cable detection output signal in response to determining that the cable is not connected to the cable connector; and
generating a positive cable detection output signal in response to determining that the cable is connected to the cable connector.
3. The method of claim 1 , wherein the cable connector has multiple pins for communicating multiple signals between the first device and the second device.
4. The method of claim 1 , wherein the first device and the second device are compute nodes.
5. The method of claim 1 , wherein the input-only pin has an impedance less than 1 K ohm.
6. The method of claim 1 , wherein the second signal is generated by a signal generator including a resistor that has an impedance between 1 M ohm and 10 M ohm.
7. The method of claim 1 , wherein the second signal is generated by a signal generator including a resistor that has an impedance that is greater than an impedance of a driver of the second device that drives the first signal onto the input-only pin when a cable connects the second device to the cable connector on the first device.
8. The method of claim 1 , further comprising:
averaging the signal on the input-only pin to avoid a false positive cable detection output.
9. The method of claim 1 , wherein determining that a cable is not connected to the cable connector and determining that the cable is connected to the cable connector is performed by a baseboard management module.
10. The method of claim 2 , wherein determining that a cable is not connected to the cable connector and determining that the cable is connected to the cable connector is performed by a detection module; and
the detection module providing a cable detection output to a baseboard management module.