Transmission apparatus and transmission method

1. A transmission apparatus comprising:

a logic circuit configured to perform a predetermined process, and output a logic output signal depending on the process;

an open-drain signal generation circuit connectable at an input terminal to the logic circuit and at an output terminal to a pull-up resistor and configured to output an output signal representing “0” when the logic output signal representing “0” is inputted into the input terminal from the logic circuit, and output an output signal representing Hi-Z when the logic output signal representing “1” is inputted into the input terminal from the logic circuit;

a signal line coupled to the open-drain signal generation circuit and a transmission path which transmits the output signal to another transmission apparatus; and

a transmission path failure determination circuit configured to determine whether there is a failure in the transmission path,

wherein the transmission path failure determination circuit includes an edge waveform information obtaining circuit for obtaining edge waveform information indicating a waveform of at least one of a rising edge and a falling edge of an application signal which is applied to the output terminal of the open-drain signal generation circuit, and a failure determination circuit for determining whether the edge waveform information satisfies a predetermined condition, and outputting a failure signal indicating that there is a failure in the transmission path when determining that the edge waveform information does not satisfy the predetermined condition.

2. The transmission apparatus according to claim 1 , wherein the edge waveform information obtaining circuit includes an edge counter for counting at least one of the number of rising edges and the number of falling edges of the application signal, and obtaining the counted number as the edge waveform information.

3. The transmission apparatus according to claim 2 , wherein the failure determination circuit obtains the counted number as the edge waveform information, in response to at least one of a rising edge and a falling edge of the logic output signal, determines whether the counted number is equal to “1”, and outputs the failure signal when the failure determination circuit determines that the counted number is not equal to “1”.

4. The transmission apparatus according to claim 1 , wherein the edge waveform information obtaining circuit includes a first edge counter for counting at least one of the number of rising edges and the number of falling edges of the logic output signal, and obtaining the counted number as first edge waveform information, and a second edge counter for counting at least one of the number of rising edges and the number of falling edges of the application signal, and obtaining the counted number as second edge waveform information, and the failure determination circuit obtains the first edge waveform information and the second edge waveform information, determines whether the counted number corresponding to the first edge waveform information is equal to the counted number corresponding to the second edge waveform information, and outputs the failure signal when the edge waveform information obtaining circuit determines that the counted number corresponding to the first edge waveform information is not equal to the counted number corresponding to the second edge waveform information.

5. The transmission apparatus according to claim 1 , wherein the transmission path failure determination circuit further includes a determination instruction signal generation circuit including an edge detection circuit for detecting at least one of a rising edge and a falling edge of the logic output signal, and outputting an edge detection signal, and a delay circuit for outputting a determination instruction signal by delaying the edge detection signal, and the failure determination circuit determines whether the edge waveform information satisfies the predetermined condition, in response to input of the determination instruction signal into the failure determination circuit.

6. A transmission method comprising:

performing, by a logic circuit in a transmission apparatus, a predetermined process to output a logic output signal depending on the process;

outputting, by an open-drain signal generation circuit connectable at an input terminal to the logic circuit and at an output terminal to a pull-up resistor, an output signal representing “0” when the logic output signal representing “0” is inputted into the input terminal from the logic circuit, and outputting an output signal representing Hi-Z when the logic output signal representing “1” is inputted into the input terminal from the logic circuit, the output signal being transmitted in a signal line coupled to the open-drain signal generation circuit and a transmission path which transmits the output signal to another transmission apparatus; and

determining, by a transmission path failure determination circuit, whether there is a failure in the transmission path,

wherein the determining includes:

obtaining edge waveform information indicating a waveform of at least one of a rising edge and a falling edge of an application signal which is applied to the output terminal of the open-drain signal generation circuit;

deciding whether the edge waveform information satisfies a predetermined condition; and

outputting a failure signal indicating that there is a failure in the transmission path when deciding that the edge waveform information does not satisfy a predetermined condition.

7. The transmission method according to claim 6 , wherein the determining includes:

counting at least one of the number of rising edges and the number of falling edges of the application signal; and

obtaining the counted number as the edge waveform information.

8. The transmission method according to claim 7 , wherein the determining includes:

obtaining the counted number as the edge waveform information, in response to at least one of a rising edge and a falling edge of the logic output signal;

detecting whether the counted number is equal to “1”; and

outputting the failure signal when detecting that the counted number is not equal to “1”.

9. The transmission method according to claim 6 , wherein the determining includes:

counting at least one of the number of rising edges and the number of falling edges of the logic output signal;

obtaining the counted number as first edge waveform information;

counting at least one of the number of rising edges and the number of falling edges of the application signal;

obtaining the counted number as second edge waveform information;

determining whether the counted number corresponding to the first edge waveform information is equal to the counted number corresponding to the second edge waveform information; and

outputting the failure signal when determining that the counted number corresponding to the first edge waveform information is not equal to the counted number corresponding to the second edge waveform information.

10. The transmission method according to claim 6 , wherein the determining includes:

detecting at least one of a rising edge and a falling edge of the logic output signal;

outputting an edge detection signal;

outputting a determination instruction signal by delaying the edge detection signal; and

determining whether the edge waveform information satisfies the predetermined condition, in response to input of the determination instruction signal.