Single-thread detection of valid synchronization headers
An integrated circuit with an interface circuit is described. During operation, the interface circuit may receive signals corresponding to a header of a frame that is compatible with a serial communication protocol, where the received signals include a temporal pattern of binary bits with instances of a dominant signal level and a recessive signal level. Then, the interface circuit may compute a set of conditions based at least in part on the receive signals, where, when valid, the set of conditions identify a first dominant bit in the binary bits having the dominant signal level. Moreover, when the set of conditions are valid, the interface circuit may: determine a location of synchronization field in the header relative to the identified first dominant bit; and calculate a baud rate of the receive signals based at least in part on a subset of the binary bits in the synchronization field.
1 . An integrated circuit, comprising:
an interface circuit, wherein the interface circuit is configured to:
receive signals corresponding to a header of a frame that is compatible with a serial communication protocol, wherein the received signals comprise a temporal pattern of binary bits with instances of a dominant signal level and a recessive signal level;
compute a set of conditions based at least in part on the received signals, wherein, when valid, the set of conditions identify a first dominant bit in the binary bits having the dominant signal level, wherein the set of conditions comprises a first instance of a first condition, wherein, when valid, the first instance of the first condition comprises that a second dominant bit time of a second dominant bit in the binary bits having the dominant signal level is less than or equal to a first predefined multiple of a first dominant bit time of the first dominant bit, and wherein the first dominant bit precedes the second dominant bit; and
when the set of conditions are valid:
determine a location of synchronization field in the header relative to the identified first dominant bit; and
calculate a baud rate of the received signals based at least in part on a subset of the binary bits in the synchronization field.
2 . The integrated circuit of claim 1 , wherein the serial communication protocol comprises a Local Interconnect Network (LIN) communication protocol.
3 . The integrated circuit of claim 1 , wherein the dominant signal level is less than the recessive signal level.
4 . The integrated circuit of claim 1 , wherein the first predefined multiple comprises 1.25.
5 . The integrated circuit of claim 1 , wherein the set of conditions comprises a second condition; and
wherein, when valid, the second condition comprises that a sum of the second dominant bit time and a first recessive bit time of a first recessive bit in the binary bits having the recessive signal level is greater than or equal to a second predefined multiple of the first dominant bit time; and
wherein the first recessive bit is between the first dominant bit and the second dominant bit.
6 . The integrated circuit of claim 5 , wherein the second predefined multiple comprises a ratio of 2 and 11.
7 . The integrated circuit of claim 5 , wherein the set of conditions comprises a second instance of the first condition;
wherein, when valid, the second instance of the first condition comprises that a third dominant bit time of a third dominant bit in the binary bits having the dominant signal level is less than or equal to the first predefined multiple of the second dominant bit time of the second dominant bit; and
wherein the second dominant bit precedes the third dominant bit.
8 . The integrated circuit of claim 7 , wherein the set of conditions comprises a third condition;
wherein, when valid, the third condition comprises that the third dominant bit time is greater than or equal to a third predefined multiple of the second dominant bit time.
9 . The integrated circuit of claim 8 , wherein the third predefined multiple comprises 0.75.
10 . The integrated circuit of claim 9 , wherein the first predefined multiple comprises 1.25 and the third predefined multiple comprises 0.75.
11 . The integrated circuit of claim 8 , wherein the set of conditions comprises a fourth condition;
wherein, when valid, the fourth condition comprises that a sum of a second recessive bit time of a second recessive bit in the binary bits and the third dominant bit time is greater than or equal to the third predefined multiple of an average bit time of a pair of bits in the binary bits, and the sum is less than or equal to the first predefined multiple of the average bit time;
wherein the third dominant bit precedes the second recessive bit; and
wherein the pair of bits comprises the first recessive bit and a dominant bit selected from the group comprising the first dominant bit, the second dominant bit and the third dominant bit.
12 . A non-transitory computer-readable storage medium for use in conjunction with an electronic device, the computer-readable storage medium storing program instructions, wherein, when executed by the electronic device, the program instructions cause the electronic device to perform one or more operations, comprising:
receiving signals corresponding to a header of a frame that is compatible with a serial communication protocol, wherein the received signals comprise a temporal pattern of binary bits with instances of a dominant signal level and a recessive signal level;
computing a set of conditions based at least in part on the received signals, wherein, when valid, the set of conditions identify a first dominant bit in the binary bits having the dominant signal level, wherein the set of conditions comprises a first instance of a first condition, wherein, when valid, the first instance of the first condition comprises that a second dominant bit time of a second dominant bit in the binary bits having the dominant signal level is less than or equal to a first predefined multiple of a first dominant bit time of the first dominant bit, and wherein the first dominant bit precedes the second dominant bit; and
when the set of conditions are valid:
determining a location of synchronization field in the header relative to the identified first dominant bit; and
calculating a baud rate of the received signals based at least in part on a subset of the binary bits in the synchronization field.
13 . The non-transitory computer-readable storage medium of claim 12 , wherein the serial communication protocol comprises a Local Interconnect Network (LIN) communication protocol.
14 . The non-transitory computer-readable storage medium of claim 12 , wherein the dominant signal level is less than the recessive signal level.
15 . The non-transitory computer-readable storage medium of claim 12 , wherein the set of conditions comprises
a second condition; and
wherein, when valid, the second condition comprises that a sum of the second dominant bit time and a first recessive bit time of a first recessive bit in the binary bits having the recessive signal level is greater than or equal to a second predefined multiple of the first dominant bit time; and
wherein the first recessive bit is between the first dominant bit and the second dominant bit.
16 . A method for selectively calculating a baud rate of received signals, comprising:
by an electronic device:
receiving the signals corresponding to a header of a frame that is compatible with a serial communication protocol, wherein the received signals comprise a temporal pattern of binary bits with instances of a dominant signal level and a recessive signal level;
computing a set of conditions based at least in part on the received signals, wherein, when valid, the set of conditions identify a first dominant bit in the binary bits having the dominant signal level, wherein the set of conditions comprises a first instance of a first condition, wherein, when valid, the first instance of the first condition comprises that a second dominant bit time of a second dominant bit in the binary bits having the dominant signal level is less than or equal to a first predefined multiple of a first dominant bit time of the first dominant bit, and wherein the first dominant bit precedes the second dominant bit; and
when the set of conditions are valid:
determining a location of synchronization field in the header relative to the identified first dominant bit; and
calculating the baud rate of the received signals based at least in part on a subset of the binary bits in the synchronization field.
17 . The method of claim 16 , wherein the serial communication protocol comprises a Local Interconnect Network (LIN) communication protocol.
18 . The method of claim 16 , wherein the dominant signal level is less than the recessive signal level.
19 . The method of claim 16 , wherein the set of conditions comprises
a second condition; and
wherein, when valid, the second condition comprises that a sum of the second dominant bit time and a first recessive bit time of a first recessive bit in the binary bits having the recessive signal level is greater than or equal to a second predefined multiple of the first dominant bit time; and
wherein the first recessive bit is between the first dominant bit and the second dominant bit.
20 . The method of claim 16 , wherein the set of conditions comprises a second instance of the first condition;
wherein, when valid, the second instance of the first condition comprises that a third dominant bit time of a third dominant bit in the binary bits having the dominant signal level is less than or equal to the first predefined multiple of the second dominant bit time of the second dominant bit; and
wherein the second dominant bit precedes the third dominant bit.