Communication system, communication device and communication method

1 . A communication system comprising:

a host controller;

a plurality of communication devices; and

a communication path coupling the host controller and the communication devices in a ring shape and configured to transmit a communication frame for serial communications,

wherein:

the host controller includes a first error correction and detection circuit configured to detect and correct an error and having a variable error correction capability;

the communication devices each include a second error correction and detection circuit configured to detect and correct an error and having a variable error correction capability; and

the host controller is configured to output a training pattern, cause the communication devices to output the training pattern, examine errors caused in the communication path based on the training pattern, and set an error correction capability of each of the first error correction and detection circuit and the second error correction and detection circuits in accordance with the errors caused in the communication path.

2 . The communication system of claim 1 , wherein if a first number of errors are caused in a first portion of the communication path and a second number of errors are caused in a second portion of the communication path, the second number being larger than the first number, the host controller is further configured to apply an error correction capability adaptable to the second number of errors to the first portion and the second portion.

3 . The communication system of claim 1 , wherein if a first number of errors are caused in a first portion of the communication path and a second number of errors are caused in a second portion of the communication path, the second number being larger than the first number, the host controller is further configured to apply a first error correction capability adaptable to the first number of errors to the first portion and to apply a second error correction capability adaptable to the second number of errors to the second portion.

4 . The communication system of claim 3 , wherein a size of first data to which the first error correction capability is applied is equal to a size of second data to which the second error correction capability is applied.

5 . The communication system of claim 3 , wherein:

first data to which the first error correction capability is applied has a first size and is communicated at a first speed; and

second data to which the second error correction capability is applied has a second size that is larger than the first size and is communicated at a second speed that is higher than the first speed.

6 . The communication system of claim 1 , wherein the host controller is further configured to use a first communication method to output the training pattern and to communicate with the communication devices by a second communication method other than the first communication method.

7 . The communication system of claim 6 , wherein the first communication method is communication using a PAM-4 signal and the second communication method is communication using a PAM-2 signal.

8 . The communication system of claim 6 , wherein the second communication method includes a process of repeatedly transmitting the same data.

9 . The communication system of claim 6 , wherein the second communication method uses a sub-communication path which differs from the communication path and connects the host controller and the communication devices.

10 . The communication system of claim 1 , wherein if an error correction frequency or a retransmission frequency of the communication frame in one of the first error correction and detection circuit and the second error correction and detection circuits in a first portion of the communication path exceeds a reference value, the host controller is further configured to change the error correction capability for the first portion of the communication path and a second portion different from the first portion thereof in a different operation from the setting the error correction capability in accordance with the errors caused in the communication path and examined by using the training pattern.

11 . The communication system of claim 1 , wherein if an error correction frequency or a retransmission frequency of the communication frame in one of the first error correction and detection circuit and the second error correction and detection circuits in a first portion of the communication path exceeds a reference value, the host controller is further configured to change the error correction capability for the first portion of the communication path in a different operation from the setting the error correction capability in accordance with the errors caused in the communication path and examined by using the training pattern.

12 . The communication system of claim 1 , wherein the training pattern is known to the host controller and each of the communication devices.

13 . A communication device comprising:

a reception circuit configured to receive a first communication frame for serial communications from a communication path configured to couple a host controller and a plurality of communication devices in a ring shape;

a transmission circuit configured to transmit the communication frame to the communication path;

an error correction and detection circuit configured to perform error correction and detection and has a variable error correction capability; and

a controller circuit configured to set the error correction capability of the error correction and detection circuit using a known training pattern in accordance with an instruction from the host controller.

14 . A communication method in a communication system including a host controller including a first error correction and detection circuit configured to perform error correction and detection and has a variable error correction capability, a plurality of communication devices each including a second error correction and detection circuit which is configured to perform error correction and detection and which has a variable error correction capability, and a communication path coupling the host controller and the communication devices in a ring shape and configured to transmit a communication frame for serial communications,

the communication method comprising:

outputting a training pattern from the host controller and each of the communication devices;

examining errors caused in the communication path based on the training pattern; and

setting an error correction capability of each of the first error correction and detection circuit and the second error correction and detection circuits in accordance with the errors caused in the communication path.

15 . The communication method of claim 14 ,

wherein if a first number of errors are caused in a first portion of the communication path and a second number of errors are caused in a second portion of the communication path, the second number being larger than the first number, the communication method further comprises applying an error correction capability adaptable to the second number of errors to the first portion and the second portion.

16 . The communication method of claim 14 ,

wherein if a first number of errors are caused in a first portion of the communication path and a second number of errors are caused in a second portion of the communication path, the second number being larger than the first number, the communication method further comprises:

applying a first error correction capability adaptable to the first number of errors to the first portion; and

applying a second error correction capability adaptable to the second number of errors to the second portion.

17 . The communication method of claim 16 , wherein:

first data to which the first error correction capability is applied has a first size; and

second data to which the second error correction capability is applied has a second size that is larger than the first size;

the communication method further comprises:

communicating the first data at a first speed; and

communicating the second data at second speed that is higher than the first speed.

18 . The communication method of claim 14 , wherein if an error correction frequency or a retransmission frequency of the communication frame in one of the first error correction and detection circuit and the second error correction and detection circuits in a first portion of the communication path exceeds a reference value, the communication method further comprises changing the error correction capability for the first portion of the communication path and a second portion different from the first portion thereof, in a different operation from the setting the error correction capability in accordance with the errors caused in the communication path and examined by using the training pattern.

19 . The communication method of claim 14 , wherein if an error correction frequency or a retransmission frequency of the communication frame in one of the first error correction and detection circuit and the second error correction and detection circuits in a first portion of the communication path exceeds a reference value, the communication method further comprises changing the error correction capability for the first portion of the communication path, in a different operation from the setting the error correction capability in accordance with the errors caused in the communication path and examined by using the training pattern.

20 . The communication method of claim 14 , wherein the training pattern is known to the host controller and each of the communication devices.